diff --git a/test/com/google/javascript/jscomp/AmbiguatePropertiesTest.java b/test/com/google/javascript/jscomp/AmbiguatePropertiesTest.java
index 4927d854cde..4bbf0b33d0e 100644
--- a/test/com/google/javascript/jscomp/AmbiguatePropertiesTest.java
+++ b/test/com/google/javascript/jscomp/AmbiguatePropertiesTest.java
@@ -49,7 +49,6 @@ protected void setUp() throws Exception {
     enableNormalize();
     enableClosurePass();
     enableGatherExternProperties();
-    this.mode = TypeInferenceMode.BOTH;
     ignoreWarnings(
         NewTypeInference.GLOBAL_THIS,
         NewTypeInference.PROPERTY_ACCESS_ON_NONOBJECT);
@@ -1123,8 +1122,6 @@ public void testDontRenamePrototypeWithoutExterns() {
       "/** @return {!Foo} */",
       "Foo.prototype.a = function() {};");
 
-    // NTI reqires at least the MINIMAL_EXTERNS.
-    this.mode = TypeInferenceMode.OTI_ONLY;
     test(externs(""), srcs(js), expected(output));
   }
 }
diff --git a/test/com/google/javascript/jscomp/CheckAccessControlsTest.java b/test/com/google/javascript/jscomp/CheckAccessControlsTest.java
index cb8454ef60e..d8e11bcf966 100644
--- a/test/com/google/javascript/jscomp/CheckAccessControlsTest.java
+++ b/test/com/google/javascript/jscomp/CheckAccessControlsTest.java
@@ -329,10 +329,6 @@ public void testWarningForSuperclassMethod2() {
   }
 
   public void testWarningForBind() {
-    // NTI reports NTI_REDCLARED_PROPERTY here, which is as intended. If this were a new
-    // property and not the existing `bind`, then we'd report the deprecation warning as expected
-    // (see testAutoboxedDeprecatedProperty and testAutoboxedPrivateProperty).
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testDepProp(
         "/** @deprecated I'm bound to this method... */ Function.prototype.bind = function() {};"
             + "(function() {}).bind();",
@@ -467,19 +463,10 @@ public void testPrivateAccess_googModule() {
               "(new One()).m();"),
         };
 
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testError(
         srcs(js),
         error(BAD_PRIVATE_PROPERTY_ACCESS)
             .withMessage("Access to private property m of One not allowed here."));
-
-    /*
-    this.mode = TypeInferenceMode.NTI_ONLY;
-    testError(
-        srcs(js),
-        error(BAD_PRIVATE_PROPERTY_ACCESS).withMessage(
-           "Access to private property m of module$exports$example$One not allowed here."));
-           */
   }
 
   public void testNoPrivateAccessForProperties1() {
@@ -1698,9 +1685,6 @@ public void testNamespaceConstantProperty1() {
   }
 
   public void testNamespaceConstantProperty2() {
-    // NTI requires an @const annotation on namespaces, as in testNamespaceConstantProperty1.
-    // This is the only difference between the two tests.
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testError(
         "var o = {};\n"
         + "/** @const */ o.x = 1;\n"
@@ -1742,8 +1726,6 @@ public void testConstantProperty3b1() {
   }
 
   public void testConstantProperty3b2() {
-    // NTI reports NTI_REDECLARED_PROPERTY
-    this.mode = TypeInferenceMode.OTI_ONLY;
     // The old type checker should report this but it doesn't.
     testSame("/** @const */ var o = { XYZ: 1 };"
         + "o.XYZ = 2;");
@@ -1807,8 +1789,6 @@ public void testConstantProperty10a() {
   }
 
   public void testConstantProperty10b() {
-    // NTI reports NTI_REDECLARED_PROPERTY
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testSame("/** @constructor */ function Foo() { this.PROP = 1;}"
         + "Foo.prototype.PROP;");
   }
@@ -1825,9 +1805,6 @@ public void testConstantProperty11() {
   }
 
   public void testConstantProperty12() {
-    // NTI deliberately disallows this pattern (separate declaration and initialization
-    // of const properties). (b/30205953)
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testSame("/** @constructor */ function Foo() {}"
         + "/** @const */ Foo.prototype.bar;"
         + "/**\n"
diff --git a/test/com/google/javascript/jscomp/CheckConformanceTest.java b/test/com/google/javascript/jscomp/CheckConformanceTest.java
index 9f4283b6421..1fe69f5d150 100644
--- a/test/com/google/javascript/jscomp/CheckConformanceTest.java
+++ b/test/com/google/javascript/jscomp/CheckConformanceTest.java
@@ -1400,7 +1400,6 @@ public void testCustomBanUnknownInterfaceProp1() {
             "  a.gak();",
             "}");
 
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testWarning(
         js,
         CheckConformance.CONFORMANCE_VIOLATION,
@@ -1524,17 +1523,11 @@ public void testCustomBanUnresolvedType() {
         + "  error_message: 'BanUnresolvedType Message'\n"
         + "}";
 
-    // NOTE(aravindpg): In NTI we annotate the node `a` with its inferred type instead of Unknown,
-    // and so this test doesn't recognize `a` as unresolved. Fixing this is undesirable.
-    // However, we do intend to add warnings for unfulfilled forward declares, which essentially
-    // addresses this use case.
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testWarning(
         "goog.forwardDeclare('Foo'); /** @param {Foo} a */ function f(a) {a.foo()};",
         CheckConformance.CONFORMANCE_VIOLATION,
         "Violation: BanUnresolvedType Message\nReference to type 'Foo' never resolved.");
 
-    this.mode = TypeInferenceMode.BOTH;
     testNoWarning(lines(
         "/** @suppress {newCheckTypes}",
         " *  @param {!Object<string, ?>} data",
@@ -1552,9 +1545,6 @@ public void testCustomStrictBanUnresolvedType() {
         + "  error_message: 'StrictBanUnresolvedType Message'\n"
         + "}";
 
-    // NTI doesn't model unresolved types separately from unknown, so this check always results
-    // in conformance.
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testWarning(
         "goog.forwardDeclare('Foo'); /** @param {Foo} a */ var f = function(a) {}",
         CheckConformance.CONFORMANCE_VIOLATION,
diff --git a/test/com/google/javascript/jscomp/CheckTemplateParamsTest.java b/test/com/google/javascript/jscomp/CheckTemplateParamsTest.java
index 147dabd2bcb..6c91a8e2865 100644
--- a/test/com/google/javascript/jscomp/CheckTemplateParamsTest.java
+++ b/test/com/google/javascript/jscomp/CheckTemplateParamsTest.java
@@ -17,7 +17,6 @@
 package com.google.javascript.jscomp;
 
 import static com.google.javascript.jscomp.RhinoErrorReporter.TOO_MANY_TEMPLATE_PARAMS;
-import static com.google.javascript.jscomp.newtypes.JSTypeCreatorFromJSDoc.INVALID_GENERICS_INSTANTIATION;
 
 /**
  * Tests for the "Too many template parameters" warning. Ideally this would be part of
@@ -25,12 +24,6 @@
  * (as strings) not ones from JSTypeRegistry (as DiagnosticTypes).
  */
 public final class CheckTemplateParamsTest extends TypeICompilerTestCase {
-  @Override
-  protected void setUp() throws Exception {
-    super.setUp();
-    this.mode = TypeInferenceMode.BOTH;
-  }
-
   @Override
   protected int getNumRepetitions() {
     return 1;
@@ -54,7 +47,7 @@ public void testArray() {
     testSame("/** @type {!Array<string>} */ var x;");
     test(
         srcs("/** @type {!Array<string, number>} */ var x;"),
-        warningOtiNti(TOO_MANY_TEMPLATE_PARAMS, INVALID_GENERICS_INSTANTIATION));
+        warning(TOO_MANY_TEMPLATE_PARAMS));
   }
 
   public void testObject() {
@@ -63,7 +56,7 @@ public void testObject() {
     testSame("/** @type {!Object<string, number>} */ var x;");
     test(
         srcs("/** @type {!Object<string, number, boolean>} */ var x;"),
-        warningOtiNti(TOO_MANY_TEMPLATE_PARAMS, INVALID_GENERICS_INSTANTIATION));
+        warning(TOO_MANY_TEMPLATE_PARAMS));
   }
 
   public void testClass() {
@@ -72,7 +65,7 @@ public void testClass() {
         srcs(lines(
             "/** @constructor */ function SomeClass() {};",
             "/** @type {!SomeClass<string>} */ var x;")),
-        warningOtiNti(TOO_MANY_TEMPLATE_PARAMS, INVALID_GENERICS_INSTANTIATION));
+        warning(TOO_MANY_TEMPLATE_PARAMS));
 
     testSame(lines(
         "/** @constructor @template T */ function SomeClass() {};",
@@ -82,7 +75,7 @@ public void testClass() {
         srcs(lines(
             "/** @constructor @template T */ function SomeClass() {};",
             "/** @type {!SomeClass<number, string>} */ var x;")),
-        warningOtiNti(TOO_MANY_TEMPLATE_PARAMS, INVALID_GENERICS_INSTANTIATION));
+        warning(TOO_MANY_TEMPLATE_PARAMS));
   }
 
 }
diff --git a/test/com/google/javascript/jscomp/CheckUnusedPrivatePropertiesTest.java b/test/com/google/javascript/jscomp/CheckUnusedPrivatePropertiesTest.java
index 2599253836b..19ae9b65be0 100644
--- a/test/com/google/javascript/jscomp/CheckUnusedPrivatePropertiesTest.java
+++ b/test/com/google/javascript/jscomp/CheckUnusedPrivatePropertiesTest.java
@@ -82,7 +82,7 @@ public void testConstructorPropertyUsed1() {
   }
 
   public void testClassPropUnused1() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
 
     // A property defined on "this" can be removed
     unused("class C { constructor() { /** @private */ this.a = 2 } }");
@@ -94,7 +94,7 @@ public void testClassPropUnused2() {
   }
 
   public void testClassMethodUnused1() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
 
     unused("class C { constructor() {}  /** @private */ method() {} }");
     used("class C { constructor() {}  /** @private */ method() {} }\n new C().method();");
@@ -102,7 +102,7 @@ public void testClassMethodUnused1() {
 
   // The JSDoc seems to be missing here, reenable this test when it is fixed.
   public void disable_testClassMethodUnused2() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
 
     unused("class C { constructor() {}\n  /** @private */ ['method']() {} }");
     used("class C { constructor() {}\n  /** @private */ ['method']() {} }\n new C()['method']();");
diff --git a/test/com/google/javascript/jscomp/ClosureRewriteClassTest.java b/test/com/google/javascript/jscomp/ClosureRewriteClassTest.java
index 62b6695e7f3..63e3907e3aa 100644
--- a/test/com/google/javascript/jscomp/ClosureRewriteClassTest.java
+++ b/test/com/google/javascript/jscomp/ClosureRewriteClassTest.java
@@ -41,17 +41,12 @@ public final class ClosureRewriteClassTest extends TypeICompilerTestCase {
       "goog.defineClass = function(a,b) {};",
       "var use;");
 
-  private static final Diagnostic INSTANTIATE_ABSTRACT_CLASS = warningOtiNti(
-      TypeCheck.INSTANTIATE_ABSTRACT_CLASS,
-      NewTypeInference.CANNOT_INSTANTIATE_ABSTRACT_CLASS);
+  private static final Diagnostic INSTANTIATE_ABSTRACT_CLASS =
+      warning(TypeCheck.INSTANTIATE_ABSTRACT_CLASS);
 
-  private static final Diagnostic NOT_A_CONSTRUCTOR = warningOtiNti(
-      TypeCheck.NOT_A_CONSTRUCTOR,
-      NewTypeInference.NOT_A_CONSTRUCTOR);
+  private static final Diagnostic NOT_A_CONSTRUCTOR = warning(TypeCheck.NOT_A_CONSTRUCTOR);
 
-  private static final Diagnostic INEXISTENT_PROPERTY = warningOtiNti(
-      TypeCheck.INEXISTENT_PROPERTY,
-      NewTypeInference.INEXISTENT_PROPERTY);
+  private static final Diagnostic INEXISTENT_PROPERTY = warning(TypeCheck.INEXISTENT_PROPERTY);
 
   public ClosureRewriteClassTest() {
     super(EXTERNS);
@@ -65,7 +60,7 @@ protected CompilerPass getProcessor(Compiler compiler) {
   @Override
   protected void setUp() throws Exception {
     super.setUp();
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     enableRunTypeCheckAfterProcessing();
   }
 
@@ -154,7 +149,7 @@ public void testConst() {
 
   public void testAnnotations1() {
     // verify goog.defineClass values are constructible, by default
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testRewrite(
         "var x = goog.defineClass(Object, {\n"
         + "  constructor: function(){}\n"
@@ -168,7 +163,7 @@ public void testAnnotations1() {
 
   public void testAnnotations2a() {
     // @interface is preserved
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testRewriteWarning(
         lines(
             "var x = goog.defineClass(null, {",
@@ -185,7 +180,7 @@ public void testAnnotations2a() {
 
   public void testAnnotations2b() {
     // @interface is preserved, at the class level too
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testRewriteWarning(
         lines(
             "/** @interface */",
@@ -200,7 +195,7 @@ public void testAnnotations2b() {
 
   public void testAnnotations3a() {
     // verify goog.defineClass is a @struct by default
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testRewriteWarning(
         lines(
             "var y = goog.defineClass(null, {",
@@ -222,8 +217,8 @@ public void testAnnotations3a() {
 
   public void testAnnotations3b() {
     // verify goog.defineClass is a @struct by default, but can be overridden (only in OTI)
-    this.mode = TypeInferenceMode.BOTH;
-    testRewriteWarning(
+    this.mode = TypeInferenceMode.CHECKED;
+    testRewrite(
         lines(
             "/** @unrestricted */",
             "var y = goog.defineClass(null, {",
@@ -239,8 +234,7 @@ public void testAnnotations3b() {
             "/** @constructor @struct @extends {y} */",
             "var x = function() {this.a = 1};",
             "goog.inherits(x,y);",
-            "use(new y().a);"),
-        warningOtiNti(null, NewTypeInference.INEXISTENT_PROPERTY));
+            "use(new y().a);"));
   }
 
   public void testRecordAnnotations() {
@@ -255,7 +249,7 @@ public void testRecordAnnotations() {
   }
 
   public void testRecordAnnotations2() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testRewrite(
         "/** @record */\n"
         + "var Rec = goog.defineClass(null, {f : function() {}});\n"
@@ -269,7 +263,7 @@ public void testRecordAnnotations2() {
 
   public void testAbstract1() {
     // @abstract is preserved
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testRewriteWarning(
         lines(
             "var x = goog.defineClass(null, {",
@@ -286,7 +280,7 @@ public void testAbstract1() {
 
   public void testAbstract2() {
     // @abstract is preserved, at the class level too
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testRewriteWarning(
         lines(
             "/** @abstract */",
diff --git a/test/com/google/javascript/jscomp/CodePrinterTest.java b/test/com/google/javascript/jscomp/CodePrinterTest.java
index 4109c4b72df..debfd62071b 100644
--- a/test/com/google/javascript/jscomp/CodePrinterTest.java
+++ b/test/com/google/javascript/jscomp/CodePrinterTest.java
@@ -1543,7 +1543,7 @@ void setOptions(CompilerOptions options) {
   private void assertTypeAnnotations(String js, String expected) {
     assertEquals(
         expected,
-        new CodePrinter.Builder(parse(js, TypeInferenceMode.OTI_ONLY))
+        new CodePrinter.Builder(parse(js, TypeInferenceMode.CHECKED))
             .setCompilerOptions(newCompilerOptions(new CompilerOptionBuilder() {
               @Override
               void setOptions(CompilerOptions options) {
@@ -1994,13 +1994,13 @@ void setOptions(CompilerOptions options) {
 
   public void testStrict() {
     String result =
-        defaultBuilder(parse("var x", TypeInferenceMode.OTI_ONLY)).setTagAsStrict(true).build();
+        defaultBuilder(parse("var x", TypeInferenceMode.CHECKED)).setTagAsStrict(true).build();
     assertEquals("'use strict';var x", result);
   }
 
   public void testStrictPretty() {
     String result =
-        defaultBuilder(parse("var x", TypeInferenceMode.OTI_ONLY))
+        defaultBuilder(parse("var x", TypeInferenceMode.CHECKED))
             .setTagAsStrict(true)
             .setPrettyPrint(true)
             .build();
@@ -2009,13 +2009,13 @@ public void testStrictPretty() {
 
   public void testExterns() {
     String result =
-        defaultBuilder(parse("var x", TypeInferenceMode.OTI_ONLY)).setTagAsExterns(true).build();
+        defaultBuilder(parse("var x", TypeInferenceMode.CHECKED)).setTagAsExterns(true).build();
     assertEquals("/** @externs */\nvar x", result);
   }
 
   public void testIjs() {
     String result =
-        defaultBuilder(parse("var x", TypeInferenceMode.OTI_ONLY))
+        defaultBuilder(parse("var x", TypeInferenceMode.CHECKED))
             .setTagAsTypeSummary(true)
             .build();
     assertEquals("/** @fileoverview @typeSummary */\nvar x", result);
diff --git a/test/com/google/javascript/jscomp/CodePrinterTestBase.java b/test/com/google/javascript/jscomp/CodePrinterTestBase.java
index 094decb0d01..06a624e5fba 100644
--- a/test/com/google/javascript/jscomp/CodePrinterTestBase.java
+++ b/test/com/google/javascript/jscomp/CodePrinterTestBase.java
@@ -15,8 +15,6 @@
  */
 package com.google.javascript.jscomp;
 
-import static com.google.common.base.Preconditions.checkArgument;
-
 import com.google.common.collect.ImmutableList;
 import com.google.javascript.jscomp.CompilerOptions.LanguageMode;
 import com.google.javascript.jscomp.TypeICompilerTestCase.TypeInferenceMode;
@@ -44,11 +42,10 @@ protected void setUp() throws Exception {
   }
 
   Node parse(String js) {
-    return parse(js, TypeInferenceMode.NEITHER);
+    return parse(js, TypeInferenceMode.DISABLED);
   }
 
   Node parse(String js, TypeInferenceMode mode) {
-    checkArgument(mode != TypeInferenceMode.BOTH);
     Compiler compiler = new Compiler();
     lastCompiler = compiler;
     CompilerOptions options = new CompilerOptions();
@@ -67,7 +64,7 @@ Node parse(String js, TypeInferenceMode mode) {
     Node root = externsAndJs.getLastChild();
     Node externs = externsAndJs.getFirstChild();
 
-    if (mode.runsOTI()) {
+    if (mode.runsTypeCheck()) {
       DefaultPassConfig passConfig = new DefaultPassConfig(null);
       CompilerPass typeResolver = passConfig.resolveTypes.create(compiler);
       typeResolver.process(externs, root);
diff --git a/test/com/google/javascript/jscomp/DeclaredGlobalExternsOnWindowTest.java b/test/com/google/javascript/jscomp/DeclaredGlobalExternsOnWindowTest.java
index 670e593e360..4bb9c18eab8 100644
--- a/test/com/google/javascript/jscomp/DeclaredGlobalExternsOnWindowTest.java
+++ b/test/com/google/javascript/jscomp/DeclaredGlobalExternsOnWindowTest.java
@@ -30,7 +30,6 @@ protected void setUp() throws Exception {
     super.setUp();
     setAcceptedLanguage(LanguageMode.ECMASCRIPT_2017);
     allowExternsChanges();
-    this.mode = TypeInferenceMode.BOTH;
     enableRunTypeCheckAfterProcessing();
   }
 
@@ -177,12 +176,10 @@ public void testWindowPropertyWithJsDoc() {
             "/** @param {number} n*/",
             "function f(n) {}",
             "f(window.x);")),
-        warningOtiNti(TypeValidator.TYPE_MISMATCH_WARNING, NewTypeInference.INVALID_ARGUMENT_TYPE));
+        warning(TypeValidator.TYPE_MISMATCH_WARNING));
   }
 
   public void testEnum() {
-    // TODO(sdh): figure out why NTI doesn't recognize props if 'window' not explicitly declared
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testSame(
         externs(lines(
             MINIMAL_EXTERNS,
@@ -208,8 +205,6 @@ public void testConstructorIsSameType() {
             "function bar(f) {}",
             "bar(new Foo());")));
 
-    // TODO(sdh): figure out why NTI doesn't recognize props if 'window' not explicitly declared
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testSame(
         externs(lines(
             MINIMAL_EXTERNS,
diff --git a/test/com/google/javascript/jscomp/DevirtualizePrototypeMethodsTest.java b/test/com/google/javascript/jscomp/DevirtualizePrototypeMethodsTest.java
index 79e0583b1ce..a53e54a64b4 100644
--- a/test/com/google/javascript/jscomp/DevirtualizePrototypeMethodsTest.java
+++ b/test/com/google/javascript/jscomp/DevirtualizePrototypeMethodsTest.java
@@ -44,7 +44,7 @@ protected int getNumRepetitions() {
   @Override
   protected void setUp() throws Exception {
     super.setUp();
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
   }
 
   /**
@@ -89,7 +89,7 @@ public void testRewritePrototypeMethodsWithCorrectTypes() throws Exception {
             "JSCompiler_StaticMethods_bar(o, 2);",
             "JSCompiler_StaticMethods_baz(o)");
 
-    this.mode = TypeInferenceMode.OTI_ONLY;
+    this.mode = TypeInferenceMode.CHECKED;
     test(input, expected);
     checkTypeOfRewrittenMethods();
   }
diff --git a/test/com/google/javascript/jscomp/DisambiguatePropertiesTest.java b/test/com/google/javascript/jscomp/DisambiguatePropertiesTest.java
index 6a75fefa05a..1198ef7fcd8 100644
--- a/test/com/google/javascript/jscomp/DisambiguatePropertiesTest.java
+++ b/test/com/google/javascript/jscomp/DisambiguatePropertiesTest.java
@@ -469,7 +469,6 @@ public void testIgnoreUnknownType() {
         + "var F = new Foo;F.blah=0;"
         + "var U=function(){return{}};U().blah()";
 
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testSets(js, expected, "{}");
   }
 
@@ -581,7 +580,6 @@ public void testStaticProperty() {
       + "Bar.a = 0;";
     String output;
 
-    this.mode = TypeInferenceMode.OTI_ONLY;
     output = ""
         + "/** @constructor */ function Foo(){}"
         + "/** @constructor */ function Bar(){}"
@@ -701,7 +699,6 @@ public void testUntypedCodeWrongDisambiguation1() {
         + "var arr = [new Foo, new Bar];\n"
         + "var /** !Foo */z = arr[1];\n"
         + "z.Foo$p1;\n";
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testSets(js, output, "{p1=[[Bar], [Foo]]}");
   }
 
@@ -1367,7 +1364,6 @@ public void testInvalidatingInterface() {
         + "(new Foo).a = 0;"
         + "/** @interface */ function I() {};\n"
         + "I.prototype.a;\n";
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testSets(js, "{}", TypeValidator.TYPE_MISMATCH_WARNING);
   }
 
@@ -1555,7 +1551,6 @@ public void testConstructorsWithTypeErrorsAreNotDisambiguated() {
         "",
         "(new Bar()).alias();");
 
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testSets("", js, js, "{}", TypeValidator.TYPE_MISMATCH_WARNING, "assignment\n"
             + "found   : function(new:Foo): undefined\n"
             + "required: function(new:Bar): undefined");
@@ -1808,7 +1803,6 @@ public void testDontInvalidateForGenericsMismatch() {
         "  this.Bar$prop = 123;",
         "}");
 
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testSets(js, output, "{prop=[[Bar], [Foo]]}");
   }
 
@@ -1962,7 +1956,6 @@ public void testMismatchInvalidation() {
         + "var F = new Bar;\n"
         + "F.a = 0;";
 
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testSets("", js, js, "{}", TypeValidator.TYPE_MISMATCH_WARNING,
         lines(
             "initializing variable",
@@ -1977,7 +1970,6 @@ public void testBadCast() {
         + "Bar.prototype.a = 0;\n"
         + "var a = /** @type {!Foo} */ (new Bar);\n"
         + "a.a = 4;";
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testSets("", js, js, "{}", TypeValidator.INVALID_CAST,
              "invalid cast - must be a subtype or supertype\n"
              + "from: Bar\n"
@@ -2023,7 +2015,6 @@ public void testObjectLiteral() {
         + "Bar.prototype.Bar_prototype$a;\n"
         + "var F = /** @type {Foo} */ ({ Foo_prototype$a: 'a' });";
 
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testSets(js, output, "{a=[[Bar.prototype], [Foo.prototype]]}");
   }
 
@@ -2321,7 +2312,6 @@ public void testIgnoreSpecializedProperties2() {
         "  this.Foo$num = 123;",
         "}");
 
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testSets("", js, otiOutput, "{num=[[Foo], [function(): undefined]]}");
   }
 
diff --git a/test/com/google/javascript/jscomp/Es6RewriteBlockScopedDeclarationTest.java b/test/com/google/javascript/jscomp/Es6RewriteBlockScopedDeclarationTest.java
index 6776a545bbf..74b68761f2c 100644
--- a/test/com/google/javascript/jscomp/Es6RewriteBlockScopedDeclarationTest.java
+++ b/test/com/google/javascript/jscomp/Es6RewriteBlockScopedDeclarationTest.java
@@ -35,7 +35,6 @@ protected void setUp() throws Exception {
     setAcceptedLanguage(LanguageMode.ECMASCRIPT_2015);
     enableTypeCheck();
     enableTypeInfoValidation();
-    this.mode = TypeInferenceMode.OTI_ONLY;
   }
 
   @Override
@@ -1287,10 +1286,8 @@ public void testNormalizeDeclarations() {
   }
 
   public void testTypeAnnotationsOnLetConst() {
-    this.mode = TypeInferenceMode.BOTH;
-
     Diagnostic mismatch =
-        warningOtiNti(TypeValidator.TYPE_MISMATCH_WARNING, NewTypeInference.MISTYPED_ASSIGN_RHS);
+        warning(TypeValidator.TYPE_MISMATCH_WARNING);
 
     test(srcs("/** @type {number} */ let x = 5; x = 'str';"), mismatch);
     test(srcs("let /** number */ x = 5; x = 'str';"), mismatch);
@@ -1304,8 +1301,6 @@ public void testTypeAnnotationsOnLetConst() {
   }
 
   public void testDoWhileForOfCapturedLetAnnotated() {
-    this.mode = TypeInferenceMode.BOTH;
-
     test(
         lines(
             "while (true) {",
@@ -1334,7 +1329,7 @@ public void testDoWhileForOfCapturedLetAnnotated() {
                 "  (function() { x++; })();",
                 "  x = 'str';",
                 "}")),
-        warningOtiNti(TypeValidator.TYPE_MISMATCH_WARNING, null));
+        warning(TypeValidator.TYPE_MISMATCH_WARNING));
 
     test(
         srcs(
@@ -1343,7 +1338,7 @@ public void testDoWhileForOfCapturedLetAnnotated() {
                 "  (function() { x++; })();",
                 "  x = 'str';",
                 "}")),
-        warningOtiNti(TypeValidator.TYPE_MISMATCH_WARNING, null));
+        warning(TypeValidator.TYPE_MISMATCH_WARNING));
   }
 
   public void testLetForInitializers() {
diff --git a/test/com/google/javascript/jscomp/Es6RewriteBlockScopedFunctionDeclarationTest.java b/test/com/google/javascript/jscomp/Es6RewriteBlockScopedFunctionDeclarationTest.java
index 67953408485..ccf1995eba1 100644
--- a/test/com/google/javascript/jscomp/Es6RewriteBlockScopedFunctionDeclarationTest.java
+++ b/test/com/google/javascript/jscomp/Es6RewriteBlockScopedFunctionDeclarationTest.java
@@ -19,14 +19,13 @@
 import com.google.javascript.jscomp.CompilerOptions.LanguageMode;
 
 /** Test case for {@link Es6RewriteBlockScopedFunctionDeclaration}. */
-public final class Es6RewriteBlockScopedFunctionDeclarationTest extends TypeICompilerTestCase {
+public final class Es6RewriteBlockScopedFunctionDeclarationTest extends CompilerTestCase {
 
   @Override
   protected void setUp() throws Exception {
     super.setUp();
     setAcceptedLanguage(LanguageMode.ECMASCRIPT_2015);
     enableRunTypeCheckAfterProcessing();
-    this.mode = TypeInferenceMode.NEITHER;
   }
 
   @Override
diff --git a/test/com/google/javascript/jscomp/Es6RewriteDestructuringTest.java b/test/com/google/javascript/jscomp/Es6RewriteDestructuringTest.java
index 78230f67c7e..b301341806a 100644
--- a/test/com/google/javascript/jscomp/Es6RewriteDestructuringTest.java
+++ b/test/com/google/javascript/jscomp/Es6RewriteDestructuringTest.java
@@ -25,7 +25,7 @@ public class Es6RewriteDestructuringTest extends TypeICompilerTestCase {
   protected void setUp() throws Exception {
     super.setUp();
     setAcceptedLanguage(LanguageMode.ECMASCRIPT_2015);
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     enableRunTypeCheckAfterProcessing();
   }
 
@@ -468,7 +468,7 @@ public void testDefaultValueInObjectPattern() {
   }
 
   public void testDefaultParameters() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     test(
         "function f(/** ? */ zero, /** ?= */ one = 1, /** ?= */ two = 2) {}; f(1); f(1,2,3);",
         lines(
@@ -486,7 +486,7 @@ public void testDefaultParameters() {
                 "  one = (one === undefined) ? 1 : one;",
                 "  two = (two === undefined) ? 2 : two;",
                 "}; f();")),
-        warningOtiNti(TypeCheck.WRONG_ARGUMENT_COUNT, NewTypeInference.WRONG_ARGUMENT_COUNT));
+        warning(TypeCheck.WRONG_ARGUMENT_COUNT));
   }
 
   public void testDefaultAndRestParameters() {
@@ -506,7 +506,7 @@ public void testDefaultAndRestParameters() {
   }
 
   public void testDefaultUndefinedParameters() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     test("function f(zero, one=undefined) {}", "function f(zero, one) {}");
 
@@ -536,7 +536,7 @@ public void testCatch() {
   }
 
   public void testTypeCheck() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     test(
         "/** @param {{x: number}} obj */ function f({x}) {}",
@@ -549,7 +549,7 @@ public void testTypeCheck() {
 
     test(
         srcs(lines("/** @param {{x: number}} obj */", "function f({x}) {}", "f({ x: 'str'});")),
-        warningOtiNti(TypeValidator.TYPE_MISMATCH_WARNING, NewTypeInference.INVALID_ARGUMENT_TYPE));
+        warning(TypeValidator.TYPE_MISMATCH_WARNING));
 
     test(
         lines(
@@ -606,7 +606,7 @@ public void testTypeCheck() {
   }
 
   public void testDestructuringPatternInExterns() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     allowExternsChanges();
 
     testSame(
@@ -618,12 +618,12 @@ public void testDestructuringPatternInExterns() {
                 "",
                 "Foo.prototype.bar = function({a}) {};")),
         srcs("(new Foo).bar({b: 0});"),
-        warningOtiNti(TypeCheck.POSSIBLE_INEXISTENT_PROPERTY, null));
+        warning(TypeCheck.POSSIBLE_INEXISTENT_PROPERTY));
     // TODO(sdh): figure out what's going on here
   }
 
   public void testTypeCheck_inlineAnnotations() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     test(
         "function f(/** {x: number} */ {x}) {}",
@@ -635,7 +635,7 @@ public void testTypeCheck_inlineAnnotations() {
 
     test(
         srcs(lines("function f(/** {x: number} */ {x}) {}", "f({ x: 'str'});")),
-        warningOtiNti(TypeValidator.TYPE_MISMATCH_WARNING, NewTypeInference.INVALID_ARGUMENT_TYPE));
+        warning(TypeValidator.TYPE_MISMATCH_WARNING));
   }
 
   public void testDestructuringArrayNotInExprResult() {
diff --git a/test/com/google/javascript/jscomp/Es6ToEs3ConverterTest.java b/test/com/google/javascript/jscomp/Es6ToEs3ConverterTest.java
index 0fff3fc68a5..1ebda3c7d00 100644
--- a/test/com/google/javascript/jscomp/Es6ToEs3ConverterTest.java
+++ b/test/com/google/javascript/jscomp/Es6ToEs3ConverterTest.java
@@ -21,12 +21,10 @@
 import static com.google.javascript.jscomp.Es6RewriteClass.DYNAMIC_EXTENDS_TYPE;
 import static com.google.javascript.jscomp.Es6ToEs3Util.CANNOT_CONVERT;
 import static com.google.javascript.jscomp.Es6ToEs3Util.CANNOT_CONVERT_YET;
-import static com.google.javascript.jscomp.NewTypeInference.CANNOT_INSTANTIATE_ABSTRACT_CLASS;
 import static com.google.javascript.jscomp.TypeCheck.INSTANTIATE_ABSTRACT_CLASS;
 import static com.google.javascript.jscomp.parsing.parser.FeatureSet.ES7_MODULES;
 
 import com.google.javascript.jscomp.CompilerOptions.LanguageMode;
-import com.google.javascript.jscomp.newtypes.JSTypeCreatorFromJSDoc;
 import com.google.javascript.jscomp.parsing.parser.FeatureSet;
 
 /**
@@ -101,7 +99,7 @@ protected void setUp() throws Exception {
     setAcceptedLanguage(LanguageMode.ECMASCRIPT_2016);
     setLanguageOut(LanguageMode.ECMASCRIPT3);
     enableRunTypeCheckAfterProcessing();
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
   }
 
   protected final PassFactory makePassFactory(
@@ -549,11 +547,11 @@ public void testClassExpression() {
   }
 
   public void testAbstractClass() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     test(
         "/** @abstract */ class Foo {} var x = new Foo();",
         "/** @abstract @constructor @struct */ var Foo = function() {}; var x = new Foo();",
-        warningOtiNti(INSTANTIATE_ABSTRACT_CLASS, CANNOT_INSTANTIATE_ABSTRACT_CLASS));
+        warning(INSTANTIATE_ABSTRACT_CLASS));
   }
 
   /**
@@ -1657,7 +1655,7 @@ public void testGithub752() {
   }
 
   public void testInvalidClassUse() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     test(
         lines(
@@ -1687,7 +1685,7 @@ public void testInvalidClassUse() {
                 "Foo.f = function() {};",
                 "class Sub extends Foo {}",
                 "Sub.f();")),
-        warningOtiNti(TypeCheck.INEXISTENT_PROPERTY, NewTypeInference.INEXISTENT_PROPERTY));
+        warning(TypeCheck.INEXISTENT_PROPERTY));
 
     test(
         lines(
@@ -1918,7 +1916,7 @@ public void testEs5GettersAndSettersClassesWithTypes() {
   }
 
   public void testClassEs5GetterSetterIncorrectTypes() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     setLanguageOut(LanguageMode.ECMASCRIPT5);
     ignoreWarnings(
         NewTypeInference.INEXISTENT_PROPERTY, NewTypeInference.INVALID_OBJLIT_PROPERTY_TYPE);
@@ -1939,9 +1937,7 @@ public void testClassEs5GetterSetterIncorrectTypes() {
             "    get: function() {}",
             "  }",
             "});"),
-        warningOtiNti(
-            TypeValidator.TYPE_MISMATCH_WARNING,
-            JSTypeCreatorFromJSDoc.FUNCTION_WITH_NONFUNC_JSDOC));
+        warning(TypeValidator.TYPE_MISMATCH_WARNING));
 
     // Using @type instead of @param on a setter.
     test(
@@ -1959,9 +1955,7 @@ public void testClassEs5GetterSetterIncorrectTypes() {
             "    set: function(v) {}",
             "  }",
             "});"),
-        warningOtiNti(
-            TypeValidator.TYPE_MISMATCH_WARNING,
-            JSTypeCreatorFromJSDoc.FUNCTION_WITH_NONFUNC_JSDOC));
+        warning(TypeValidator.TYPE_MISMATCH_WARNING));
   }
 
   /**
@@ -2486,8 +2480,7 @@ public void testArgumentsEscaped() {
   }
 
   public void testForOfOnNonIterable() {
-    // TODO(sdh): figure out why NTI is not complaining about invalid argument type to makeIterator
-    this.mode = TypeInferenceMode.OTI_ONLY;
+    this.mode = TypeInferenceMode.CHECKED;
     test(
         srcs(
             lines(
@@ -2497,7 +2490,7 @@ public void testForOfOnNonIterable() {
                 "  length: 2,",
                 "};",
                 "for (var x of arrayLike) {}")),
-        warningOtiNti(TypeValidator.TYPE_MISMATCH_WARNING, NewTypeInference.INVALID_ARGUMENT_TYPE));
+        warning(TypeValidator.TYPE_MISMATCH_WARNING));
   }
 
   public void testSpreadCall() {
@@ -2543,7 +2536,7 @@ public void testSpreadCall() {
             "($jscomp$spread$args1 = G.d()).n.apply($jscomp$spread$args1,",
             "    $jscomp.arrayFromIterable(b));"));
 
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     test(
         srcs(
@@ -2555,7 +2548,7 @@ public void testSpreadCall() {
                 "}",
                 "var arr = [1,2]",
                 "Factory.create().m(...arr);")),
-        warningOtiNti(TypeCheck.INEXISTENT_PROPERTY, NewTypeInference.INEXISTENT_PROPERTY));
+        warning(TypeCheck.INEXISTENT_PROPERTY));
 
     test(
         lines(
diff --git a/test/com/google/javascript/jscomp/Es7ToEs6ConverterTest.java b/test/com/google/javascript/jscomp/Es7ToEs6ConverterTest.java
index 68e045263cc..de05243d657 100644
--- a/test/com/google/javascript/jscomp/Es7ToEs6ConverterTest.java
+++ b/test/com/google/javascript/jscomp/Es7ToEs6ConverterTest.java
@@ -21,7 +21,7 @@
  * Test cases for ES6 transpilation. Despite the name, this isn't just testing {@link
  * Es6ToEs3Converter}, but also some other ES6 transpilation passes. See #getProcessor.
  */
-public final class Es7ToEs6ConverterTest extends TypeICompilerTestCase {
+public final class Es7ToEs6ConverterTest extends CompilerTestCase {
 
   public Es7ToEs6ConverterTest() {
     super(MINIMAL_EXTERNS);
@@ -33,7 +33,6 @@ protected void setUp() throws Exception {
     setAcceptedLanguage(LanguageMode.ECMASCRIPT_2016);
     setLanguageOut(LanguageMode.ECMASCRIPT5);
     enableRunTypeCheckAfterProcessing();
-    this.mode = TypeInferenceMode.NEITHER;
   }
 
   @Override
diff --git a/test/com/google/javascript/jscomp/EsNextToEs8ConverterTest.java b/test/com/google/javascript/jscomp/EsNextToEs8ConverterTest.java
index 0f204932d76..c09ed069b4b 100644
--- a/test/com/google/javascript/jscomp/EsNextToEs8ConverterTest.java
+++ b/test/com/google/javascript/jscomp/EsNextToEs8ConverterTest.java
@@ -18,7 +18,7 @@
 import com.google.javascript.jscomp.CompilerOptions.LanguageMode;
 
 /** Test cases for ESNext transpilation. */
-public final class EsNextToEs8ConverterTest extends TypeICompilerTestCase {
+public final class EsNextToEs8ConverterTest extends CompilerTestCase {
 
   public EsNextToEs8ConverterTest() {
     super(MINIMAL_EXTERNS);
@@ -30,7 +30,6 @@ protected void setUp() throws Exception {
     setAcceptedLanguage(LanguageMode.ECMASCRIPT_NEXT);
     setLanguageOut(LanguageMode.ECMASCRIPT_2017);
     enableRunTypeCheckAfterProcessing();
-    this.mode = TypeInferenceMode.NEITHER;
   }
 
   @Override
diff --git a/test/com/google/javascript/jscomp/ExternExportsPassTest.java b/test/com/google/javascript/jscomp/ExternExportsPassTest.java
index 61c77af4527..8ee105ef4bf 100644
--- a/test/com/google/javascript/jscomp/ExternExportsPassTest.java
+++ b/test/com/google/javascript/jscomp/ExternExportsPassTest.java
@@ -29,7 +29,6 @@ public final class ExternExportsPassTest extends TypeICompilerTestCase {
   protected void setUp() throws Exception {
     super.setUp();
     enableNormalize();
-    this.mode = TypeInferenceMode.BOTH;
   }
 
   @Override
@@ -158,8 +157,6 @@ public void testExportMultiple() throws Exception {
   }
 
   public void testExportMultiple2() throws Exception {
-    // TODO(sdh): NTI leaves out the annotation for hello for some reason.
-    this.mode = TypeInferenceMode.OTI_ONLY;
     compileAndCheck(
         lines(
             "/** @const */ var a = {};",
@@ -334,7 +331,7 @@ public void testExportSymbolWithMultipleTemplateAnnotation() {
   public void testExportSymbolWithoutTypeCheck() {
     // ExternExportsPass should not emit annotations
     // if there is no type information available.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
 
     compileAndCheck(
         lines(
@@ -411,7 +408,7 @@ public void testExportSymbolWithConstructorWithoutTypeCheck() {
     // to JSTypes and not Nodes (and no JSTypes are created when checkTypes
     // is false), we don't really have a choice.
 
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
 
     compileAndCheck(
         lines(
@@ -581,7 +578,6 @@ public void testExportWithReferenceToEnum() {
         "};",
         "");
 
-    this.mode = TypeInferenceMode.OTI_ONLY;
     // NOTE: The type should print {E} for the @param, but is not.
     compileAndCheck(js, expected.replace("{E}", "{number}"));
   }
diff --git a/test/com/google/javascript/jscomp/ImplicitNullabilityCheckTest.java b/test/com/google/javascript/jscomp/ImplicitNullabilityCheckTest.java
index dc4c689402e..070fd1af42d 100644
--- a/test/com/google/javascript/jscomp/ImplicitNullabilityCheckTest.java
+++ b/test/com/google/javascript/jscomp/ImplicitNullabilityCheckTest.java
@@ -90,15 +90,11 @@ public void testParameterizedObject() {
   }
 
   public void testNullableTypedef() {
-    // Arguable whether or not this deserves a warning, so leaving
-    // out of NTI for now.
-    this.mode = TypeInferenceMode.OTI_ONLY;
+    // Arguable whether or not this deserves a warning
     warnImplicitlyNullable("/** @typedef {?number} */ var Num; var /** Num */ x;");
   }
 
   public void testUnknownTypenameDoesntWarn() {
-    // Different warnings in OTI and NTI
-    this.mode = TypeInferenceMode.OTI_ONLY;
     test(
         externs(DEFAULT_EXTERNS),
         srcs("/** @type {gibberish} */ var x;"),
diff --git a/test/com/google/javascript/jscomp/InlinePropertiesTest.java b/test/com/google/javascript/jscomp/InlinePropertiesTest.java
index 9ba965ffd2e..efedcd80826 100644
--- a/test/com/google/javascript/jscomp/InlinePropertiesTest.java
+++ b/test/com/google/javascript/jscomp/InlinePropertiesTest.java
@@ -91,7 +91,6 @@ protected void setUp() throws Exception {
     enableNormalize();
     enableClosurePass();
     enableGatherExternProperties();
-    this.mode = TypeInferenceMode.BOTH;
     this.runSmartNameRemoval = false;
   }
 
diff --git a/test/com/google/javascript/jscomp/J2clCheckPassTest.java b/test/com/google/javascript/jscomp/J2clCheckPassTest.java
index 5867842abe0..8796a275ebb 100644
--- a/test/com/google/javascript/jscomp/J2clCheckPassTest.java
+++ b/test/com/google/javascript/jscomp/J2clCheckPassTest.java
@@ -27,7 +27,6 @@ public J2clCheckPassTest() {
   @Override
   protected void setUp() throws Exception {
     super.setUp();
-    this.mode = TypeInferenceMode.BOTH;
   }
 
   @Override
diff --git a/test/com/google/javascript/jscomp/J2clEqualitySameRewriterPassTest.java b/test/com/google/javascript/jscomp/J2clEqualitySameRewriterPassTest.java
index 8945521122c..c13ec770470 100644
--- a/test/com/google/javascript/jscomp/J2clEqualitySameRewriterPassTest.java
+++ b/test/com/google/javascript/jscomp/J2clEqualitySameRewriterPassTest.java
@@ -25,7 +25,6 @@ public J2clEqualitySameRewriterPassTest() {
   @Override
   protected void setUp() throws Exception {
     super.setUp();
-    this.mode = TypeInferenceMode.BOTH;
   }
 
   @Override
diff --git a/test/com/google/javascript/jscomp/PeepholeFoldConstantsTest.java b/test/com/google/javascript/jscomp/PeepholeFoldConstantsTest.java
index e0f5708f885..00bffea9581 100644
--- a/test/com/google/javascript/jscomp/PeepholeFoldConstantsTest.java
+++ b/test/com/google/javascript/jscomp/PeepholeFoldConstantsTest.java
@@ -48,7 +48,7 @@ protected void setUp() throws Exception {
     useTypes = true;
     // Reduce this to 1 if we get better expression evaluators.
     numRepetitions = 2;
-    mode = TypeInferenceMode.NEITHER;
+    mode = TypeInferenceMode.DISABLED;
   }
 
   @Override
@@ -763,7 +763,7 @@ public void testStringAdd() {
   }
 
   public void testStringAdd_identity() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     foldStringTypes("x + ''", "x");
     foldStringTypes("'' + x", "x");
   }
@@ -1431,7 +1431,7 @@ public void testIssue522() {
   }
 
   public void testTypeBasedFoldConstant() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     test("function f(/** number */ x) { x + 1 + 1 + x; }",
          "function f(/** number */ x) { x + 2 + x; }");
 
@@ -1585,7 +1585,7 @@ public void testConvertToNumberNegativeInf() {
   }
 
   public void testAlgebraicIdentities() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     foldNumericTypes("x+0", "x");
     foldNumericTypes("0+x", "x");
diff --git a/test/com/google/javascript/jscomp/PeepholeMinimizeConditionsTest.java b/test/com/google/javascript/jscomp/PeepholeMinimizeConditionsTest.java
index 8a85f980cf5..52b37fd90bb 100644
--- a/test/com/google/javascript/jscomp/PeepholeMinimizeConditionsTest.java
+++ b/test/com/google/javascript/jscomp/PeepholeMinimizeConditionsTest.java
@@ -33,7 +33,7 @@ public PeepholeMinimizeConditionsTest() {
   protected void setUp() throws Exception {
     super.setUp();
     late = true;
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     // NTI warns about property accesses on *
     ignoreWarnings(DiagnosticGroups.NEW_CHECK_TYPES_EXTRA_CHECKS);
   }
@@ -777,7 +777,7 @@ public void testIssue925() {
   }
 
   public void testCoercionSubstitution_disabled() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testSame("var x = {}; if (x != null) throw 'a';");
     testSame("var x = {}; var y = x != null;");
 
@@ -786,12 +786,12 @@ public void testCoercionSubstitution_disabled() {
   }
 
   public void testCoercionSubstitution_booleanResult0() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testSame("var x = {}; var y = x != null;");
   }
 
   public void testCoercionSubstitution_booleanResult1() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testSame("var x = {}; var y = x == null;");
     testSame("var x = {}; var y = x !== null;");
     testSame("var x = undefined; var y = x !== null;");
@@ -805,7 +805,7 @@ public void testCoercionSubstitution_booleanResult1() {
   }
 
   public void testCoercionSubstitution_if() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     test("var x = {};\nif (x != null) throw 'a';\n", "var x={}; if (x!=null) throw 'a'");
     testSame("var x = {};\nif (x == null) throw 'a';\n");
     testSame("var x = {};\nif (x !== null) throw 'a';\n");
@@ -829,13 +829,13 @@ public void testCoercionSubstitution_if() {
   }
 
   public void testCoercionSubstitution_expression() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testSame("var x = {}; x != null && alert('b');");
     testSame("var x = 1; x != 0 && alert('b');");
   }
 
   public void testCoercionSubstitution_hook() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testSame(
         lines(
             "var x = {};",
@@ -847,7 +847,7 @@ public void testCoercionSubstitution_hook() {
   }
 
   public void testCoercionSubstitution_not() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     test(
         "var x = {};\nvar y = !(x != null) ? 1 : 2;\n",
         "var x = {};\nvar y = (x == null) ? 1 : 2;\n");
@@ -855,44 +855,44 @@ public void testCoercionSubstitution_not() {
   }
 
   public void testCoercionSubstitution_while() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testSame("var x = {}; while (x != null) throw 'a';");
     testSame("var x = 1; while (x != 0) throw 'a';");
   }
 
   public void testCoercionSubstitution_unknownType() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testSame("var x = /** @type {?} */ ({});\nif (x != null) throw 'a';\n");
     testSame("var x = /** @type {?} */ (1);\nif (x != 0) throw 'a';\n");
   }
 
   public void testCoercionSubstitution_allType() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testSame("var x = /** @type {*} */ ({});\nif (x != null) throw 'a';\n");
     testSame("var x = /** @type {*} */ (1);\nif (x != 0) throw 'a';\n");
   }
 
   public void testCoercionSubstitution_primitivesVsNull() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testSame("var x = 0;\nif (x != null) throw 'a';\n");
     testSame("var x = '';\nif (x != null) throw 'a';\n");
     testSame("var x = false;\nif (x != null) throw 'a';\n");
   }
 
   public void testCoercionSubstitution_nonNumberVsZero() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testSame("var x = {};\nif (x != 0) throw 'a';\n");
     testSame("var x = '';\nif (x != 0) throw 'a';\n");
     testSame("var x = false;\nif (x != 0) throw 'a';\n");
   }
 
   public void testCoercionSubstitution_boxedNumberVsZero() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testSame("var x = new Number(0);\nif (x != 0) throw 'a';\n");
   }
 
   public void testCoercionSubstitution_boxedPrimitives() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     testSame("var x = new Number(); if (x != null) throw 'a';");
     testSame("var x = new String(); if (x != null) throw 'a';");
     testSame("var x = new Boolean();\nif (x != null) throw 'a';");
diff --git a/test/com/google/javascript/jscomp/PeepholeReplaceKnownMethodsTest.java b/test/com/google/javascript/jscomp/PeepholeReplaceKnownMethodsTest.java
index 8dd75a842b5..dffe194e392 100644
--- a/test/com/google/javascript/jscomp/PeepholeReplaceKnownMethodsTest.java
+++ b/test/com/google/javascript/jscomp/PeepholeReplaceKnownMethodsTest.java
@@ -43,7 +43,7 @@ protected void setUp() throws Exception {
     super.setUp();
     late = true;
     useTypes = true;
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
   }
 
   @Override
@@ -520,7 +520,7 @@ public void testFoldParseOctalNumbers() {
   }
 
   public void testReplaceWithCharAt() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     foldStringTyped("a.substring(0, 1)", "a.charAt(0)");
     foldSameStringTyped("a.substring(-4, -3)");
     foldSameStringTyped("a.substring(i, j + 1)");
@@ -558,16 +558,13 @@ public void testReplaceWithCharAt() {
     foldSameStringTyped("a.substr(1, 2)");
     foldSameStringTyped("a.substr(1, 2, 3)");
 
-    this.mode = TypeInferenceMode.OTI_ONLY;
-    // TODO(sdh): NTI currently infers that a is a string, allowing the peephole pass
-    // to rewrite substring to charAt.  We need to figure out if this is desirable.
+    this.mode = TypeInferenceMode.CHECKED;
     foldSame("function f(/** ? */ a) { a.substring(0, 1); }");
     foldSame("function f(/** ? */ a) { a.substr(0, 1); }");
     foldSame(lines(
         "/** @constructor */ function A() {};",
         "A.prototype.substring = function() {};",
         "function f(/** ? */ a) { a.substring(0, 1); }"));
-    this.mode = TypeInferenceMode.BOTH;
     foldSame("function f(/** ? */ a) { a.slice(0, 1); }");
 
     useTypes = false;
diff --git a/test/com/google/javascript/jscomp/PolymerPassFindExternsTest.java b/test/com/google/javascript/jscomp/PolymerPassFindExternsTest.java
index b8de1b10682..7bd14d19172 100644
--- a/test/com/google/javascript/jscomp/PolymerPassFindExternsTest.java
+++ b/test/com/google/javascript/jscomp/PolymerPassFindExternsTest.java
@@ -76,7 +76,6 @@ public void process(Node externs, Node root) {
   protected void setUp() throws Exception {
     super.setUp();
     allowExternsChanges();
-    this.mode = TypeInferenceMode.BOTH;
     enableRunTypeCheckAfterProcessing();
     enableParseTypeInfo();
   }
diff --git a/test/com/google/javascript/jscomp/PolymerPassSuppressBehaviorsTest.java b/test/com/google/javascript/jscomp/PolymerPassSuppressBehaviorsTest.java
index 964803e399d..98f357b4c81 100644
--- a/test/com/google/javascript/jscomp/PolymerPassSuppressBehaviorsTest.java
+++ b/test/com/google/javascript/jscomp/PolymerPassSuppressBehaviorsTest.java
@@ -77,7 +77,6 @@ protected void setUp() throws Exception {
     super.setUp();
     setAcceptedLanguage(LanguageMode.ECMASCRIPT_2017);
     allowExternsChanges();
-    this.mode = TypeInferenceMode.BOTH;
     enableRunTypeCheckAfterProcessing();
     enableParseTypeInfo();
   }
@@ -171,7 +170,7 @@ public void testDefaultValueSuppression() {
   }
 
   public void testConstBehaviours() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "/** @polymerBehavior */",
@@ -185,7 +184,7 @@ public void testConstBehaviours() {
   }
 
   public void testLetBehaviours() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "/** @polymerBehavior */",
diff --git a/test/com/google/javascript/jscomp/PolymerPassTest.java b/test/com/google/javascript/jscomp/PolymerPassTest.java
index 551cfe0b5e6..66a94d2696b 100644
--- a/test/com/google/javascript/jscomp/PolymerPassTest.java
+++ b/test/com/google/javascript/jscomp/PolymerPassTest.java
@@ -16,7 +16,6 @@
 package com.google.javascript.jscomp;
 
 import static com.google.common.truth.Truth.assertThat;
-import static com.google.javascript.jscomp.NewTypeInference.MISTYPED_ASSIGN_RHS;
 import static com.google.javascript.jscomp.PolymerClassRewriter.POLYMER_ELEMENT_PROP_CONFIG;
 import static com.google.javascript.jscomp.PolymerPassErrors.POLYMER_CLASS_PROPERTIES_INVALID;
 import static com.google.javascript.jscomp.PolymerPassErrors.POLYMER_CLASS_PROPERTIES_NOT_STATIC;
@@ -132,7 +131,6 @@ protected void setUp() throws Exception {
     super.setUp();
     setAcceptedLanguage(LanguageMode.ECMASCRIPT_2017);
     allowExternsChanges();
-    this.mode = TypeInferenceMode.BOTH;
     enableRunTypeCheckAfterProcessing();
     enableParseTypeInfo();
   }
@@ -157,7 +155,7 @@ public void testVarTarget() {
             "});"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "var X = class extends Polymer.Element {",
@@ -175,7 +173,7 @@ public void testVarTarget() {
 
   public void testLetTarget() {
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "let X = Polymer({",
@@ -191,7 +189,7 @@ public void testLetTarget() {
             "X = Polymer(/** @lends {X.prototype} */ {is:'x-element'});"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "let X = class extends Polymer.Element {",
@@ -209,7 +207,7 @@ public void testLetTarget() {
 
   public void testConstTarget() {
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     testError(
         lines(
             "const X = Polymer({",
@@ -266,7 +264,7 @@ public void testPathAssignmentTarget() {
             "});"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "const x = {};",
@@ -287,7 +285,7 @@ public void testPathAssignmentTarget() {
   public void testComputedPropName() {
     // Type checker doesn't currently understand ES6 code. Remove when it does.
     // TypeCheck cannot grab a name from a complicated computedPropName
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test("var X = Polymer({is:'x-element', [name + (() => 42)]: function() {return 42;}});",
         lines(
             "/** @constructor @extends {PolymerElement} @implements {PolymerXInterface} */",
@@ -329,7 +327,7 @@ public void testIIFEExtractionInGlobalNamespace() {
             "})()"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "const x = {};",
@@ -380,7 +378,7 @@ public void testIIFEExtractionNoAssignmentTarget() {
             "})()"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "(function() {",
@@ -509,7 +507,7 @@ public void testOtherKeysIgnored() {
             "});"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "class X extends Polymer.Element {",
@@ -672,7 +670,7 @@ public void testPropertiesAddedToPrototype() {
             "});"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "/** @constructor */",
@@ -777,7 +775,7 @@ public void testPropertiesDefaultValueFunctions() {
             "});"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "/** @constructor */",
@@ -872,7 +870,7 @@ public void testPropertiesDefaultValueShortHandFunction() {
             "});"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "/** @constructor */",
@@ -1023,7 +1021,7 @@ public void testReadOnlyPropertySetters() {
             "Polymera_BInterface.prototype._setPets;"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String jsClass = lines(
         "class A extends Polymer.Element {",
         "  static get is() { return 'a-element'; }",
@@ -1168,7 +1166,7 @@ public void testReflectToAttributeProperties() {
 
   public void testPolymerClassObserversTyped() {
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "class FooElement extends Polymer.Element {",
@@ -1332,7 +1330,7 @@ public void testThisTypeAddedToFunctions() {
             "});"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "class Foo extends Polymer.Element {",
@@ -1446,7 +1444,7 @@ public void testDollarSignPropsConvertedToBrackets() {
             "});"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "class Foo extends Polymer.Element {",
@@ -2725,7 +2723,7 @@ public void testDuplicatedBehaviorsAreCopiedOnce() {
 
   public void testInvalid1() {
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     testWarning("var x = Polymer('blah');", POLYMER_DESCRIPTOR_NOT_VALID);
     testWarning("var x = Polymer('foo-bar', {});", POLYMER_DESCRIPTOR_NOT_VALID);
     testError("var x = Polymer({},'blah');", POLYMER_UNEXPECTED_PARAMS);
@@ -2787,7 +2785,7 @@ public void testInvalidProperties() {
         POLYMER_INVALID_PROPERTY);
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     testError(
         lines(
             "var x = class extends Polymer.Element {",
@@ -2924,12 +2922,12 @@ public void testInvalidTypeAssignment() {
             "    this.isHappy = 7;",
             "  },",
             "});"),
-        warningOtiNti(TYPE_MISMATCH_WARNING, MISTYPED_ASSIGN_RHS));
+        warning(TYPE_MISMATCH_WARNING));
   }
 
   public void testFeaturesInFunctionBody() {
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "var X = Polymer({",
@@ -2968,7 +2966,7 @@ public void testFeaturesInFunctionBody() {
 
   public void testPolymerElementAnnotation1() {
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "/** @constructor */",
@@ -3021,7 +3019,7 @@ public void testPolymerElementAnnotation1() {
 
   public void testPolymerElementAnnotation2() {
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         lines(
             "/** @constructor */",
@@ -3124,7 +3122,7 @@ public void testObjectReflectionAddedToConfigProperties1() {
             "});"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         2,
         lines(
@@ -3225,7 +3223,7 @@ public void testObjectReflectionAddedToConfigProperties2() {
             "});"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         2,
         lines(
@@ -3327,7 +3325,7 @@ public void testObjectReflectionAddedToConfigProperties3() {
             "});"));
 
     // Type checker doesn't currently understand ES6 code. Remove when it does.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     test(
         2,
         lines(
diff --git a/test/com/google/javascript/jscomp/PureFunctionIdentifierTest.java b/test/com/google/javascript/jscomp/PureFunctionIdentifierTest.java
index dff849f8fd3..a7765324378 100644
--- a/test/com/google/javascript/jscomp/PureFunctionIdentifierTest.java
+++ b/test/com/google/javascript/jscomp/PureFunctionIdentifierTest.java
@@ -577,7 +577,7 @@ public void testAnnotationInExternStubs4() throws Exception {
         " */",
         "externObj5.prototype.propWithAnnotatedStubAfter;");
 
-    this.mode = TypeInferenceMode.OTI_ONLY;
+    this.mode = TypeInferenceMode.CHECKED;
     testSame(
         externs(externs),
         srcs("o.prototype.propWithAnnotatedStubAfter"),
@@ -604,7 +604,7 @@ public void testAnnotationInExternStubs5() throws Exception {
         " */",
         "externObj5.prototype.propWithAnnotatedStubAfter;");
 
-    this.mode = TypeInferenceMode.OTI_ONLY;
+    this.mode = TypeInferenceMode.CHECKED;
     testSame(
         externs(externs),
         srcs("o.prototype.propWithAnnotatedStubAfter"),
@@ -748,11 +748,11 @@ public void testReturnLocalityMultipleDefinitionsSameName() {
   }
 
   public void testExternCalls() throws Exception {
-    testExternCallsForTypeInferenceMode(TypeInferenceMode.BOTH);
+    testExternCallsForTypeInferenceMode(TypeInferenceMode.CHECKED);
   }
 
   public void testExternCallsNoTypeChecking() throws Exception {
-    testExternCallsForTypeInferenceMode(TypeInferenceMode.NEITHER);
+    testExternCallsForTypeInferenceMode(TypeInferenceMode.DISABLED);
   }
 
   private void testExternCallsForTypeInferenceMode(TypeInferenceMode typeInferenceMode) {
@@ -919,7 +919,7 @@ public void testLocalizedSideEffects4() throws Exception {
         ImmutableList.of("f"));
 
     // TODO(bradfordcsmith): Remove NEITHER when type checker understands let/const
-    mode = TypeInferenceMode.NEITHER;
+    mode = TypeInferenceMode.DISABLED;
     assertPureCallsMarked(
         lines(
             "function f() {const x = []; x[0] = 1;}", // preserve newline
@@ -950,7 +950,7 @@ public void testLocalizedSideEffects6() throws Exception {
         ImmutableList.of("f"));
 
     // TODO(bradfordcsmith): Remove NEITHER when type checker understands let/const
-    mode = TypeInferenceMode.NEITHER;
+    mode = TypeInferenceMode.DISABLED;
     assertPureCallsMarked(
         lines(
             "function f() {", // preserve newline
@@ -973,7 +973,7 @@ public void testLocalizedSideEffects7() throws Exception {
         ImmutableList.of("f"));
 
     // TODO(bradfordcsmith): Remove NEITHER when type checker understands let/const
-    mode = TypeInferenceMode.NEITHER;
+    mode = TypeInferenceMode.DISABLED;
     assertPureCallsMarked(
         lines(
             "/** @constructor A */ function A() {};",
@@ -1059,7 +1059,7 @@ public void testLocalizedSideEffects12() throws Exception {
         ImmutableList.of("f"));
 
     // TODO(bradfordcsmith): Remove NEITHER when type checker understands let/const
-    mode = TypeInferenceMode.NEITHER;
+    mode = TypeInferenceMode.DISABLED;
     assertPureCallsMarked(
         lines(
             "function f() {const x = []; { x[0] = 1; } }", // preserve newline
@@ -1068,7 +1068,7 @@ public void testLocalizedSideEffects12() throws Exception {
   }
 
   public void testLocalizedSideEffects13() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source = lines(
         "function f() {var [x, y] = [3, 4]; }",
         "f()");
@@ -1076,7 +1076,7 @@ public void testLocalizedSideEffects13() {
   }
 
   public void testLocalizedSideEffects14() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source = lines(
         "function f() {var x; if (true) { [x] = [5]; } }",
         "f()");
@@ -1084,7 +1084,7 @@ public void testLocalizedSideEffects14() {
   }
 
   public void testLocalizedSideEffects15() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source = lines(
         "function f() {var {length} = 'a string'; }",
         "f()");
@@ -1092,7 +1092,7 @@ public void testLocalizedSideEffects15() {
   }
 
   public void testLocalizedSideEffects16() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source = lines(
         "function f(someArray) {var [a, , b] = someArray; }",
         "f()");
@@ -1100,7 +1100,7 @@ public void testLocalizedSideEffects16() {
   }
 
   public void testLocalizedSideEffects17() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source = lines(
         "function f(someObj) {var { very: { nested: { lhs: pattern }} } = someObj; }",
         "f()");
@@ -1108,7 +1108,7 @@ public void testLocalizedSideEffects17() {
   }
 
   public void testLocalizedSideEffects18() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source = lines(
         "function SomeCtor() { [this.x, this.y] = getCoordinates(); }",
         "new SomeCtor()");
@@ -1116,7 +1116,7 @@ public void testLocalizedSideEffects18() {
   }
 
   public void testLocalizedSideEffects19() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source = lines(
         "function SomeCtor() { [this.x, this.y] = [0, 1]; }",
         "new SomeCtor()");
@@ -1124,7 +1124,7 @@ public void testLocalizedSideEffects19() {
   }
 
   public void testLocalizedSideEffects20() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source = lines(
         "function SomeCtor() { this.x += 1; }",
         "new SomeCtor()");
@@ -1134,13 +1134,13 @@ public void testLocalizedSideEffects20() {
   public void testLocalizedSideEffects21() {
     // TODO(bradfordcsmith): Remove NEITHER when type checkers understand destructuring and
     // let/const.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source = lines("function f(values) { const x = {}; [x.y, x.z] = values; }", "f()");
     assertPureCallsMarked(source, ImmutableList.of("f"));
   }
 
   public void testLocalizedSideEffects22() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source = lines(
         "var x = {}; function f(values) { [x.y, x.z] = values; }",
         "f()");
@@ -1150,7 +1150,7 @@ public void testLocalizedSideEffects22() {
   public void testLocalizedSideEffects23() {
     // TODO(bradfordcsmith): Remove NEITHER when type checkers understand destructuring and
     // let/const.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source =
         lines(
             "function f(values) { const x = {}; [x.y, x.z = defaultNoSideEffects] = values; }",
@@ -1159,7 +1159,7 @@ public void testLocalizedSideEffects23() {
   }
 
   public void testLocalizedSideEffects24() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source = lines(
         "function f(values) { var x = {}; [x.y, x.z = defaultWithSideEffects()] = values; }",
         "f()");
@@ -1189,7 +1189,7 @@ public void testUnaryOperators3() throws Exception {
         ImmutableList.of("f"));
 
     // TODO(bradfordcsmith): Remove NEITHER when type checker understands let/const
-    mode = TypeInferenceMode.NEITHER;
+    mode = TypeInferenceMode.DISABLED;
     assertPureCallsMarked(
         lines(
             "function f() {const x = {foo : 0}; x.foo++}", // preserve newline
@@ -1213,7 +1213,7 @@ public void testUnaryOperators5() throws Exception {
         ImmutableList.of("f"));
 
     // TODO(bradfordcsmith): Remove NEITHER when type checker understands destructured parameters
-    mode = TypeInferenceMode.NEITHER;
+    mode = TypeInferenceMode.DISABLED;
     assertPureCallsMarked(
         lines(
             "function f({x}) {x.foo++}", // preserve newline
@@ -1513,7 +1513,7 @@ public void testAmbiguousDefinitionsMutatesLocalArgument() throws Exception {
         ImmutableList.of("C.a", "b"));
 
     // TODO(bradfordcsmith): Remove NEITHER when type checker understands destructuring parameters
-    mode = TypeInferenceMode.NEITHER;
+    mode = TypeInferenceMode.DISABLED;
     assertPureCallsMarked(
         lines(
             "// Mutates argument",
@@ -1692,7 +1692,7 @@ public void testMutatesArguments1() throws Exception {
         ImmutableList.of("f"));
 
     // TODO(bradfordcsmith): Remove NEITHER when type checker understands destructuring parameters
-    mode = TypeInferenceMode.NEITHER;
+    mode = TypeInferenceMode.DISABLED;
     assertPureCallsMarked(
         lines(
             "function f([x]) { x.y = 1; }", // preserve newline
@@ -1725,7 +1725,7 @@ public void testMutatesArguments4() throws Exception {
         ImmutableList.of("f", "g"));
 
     // TODO(bradfordcsmith): Remove NEITHER when type checker understands destructuring parameters
-    mode = TypeInferenceMode.NEITHER;
+    mode = TypeInferenceMode.DISABLED;
     assertPureCallsMarked(
         lines(
             "function f([x]) { x.y = 1; }", // preserve newline
@@ -1769,7 +1769,7 @@ public void testMutatesArgumentsArray3() throws Exception {
   }
 
   public void testCallGenerator1() {
-    this.mode = TypeInferenceMode.NEITHER; // type check for yield not yet implemented
+    this.mode = TypeInferenceMode.DISABLED; // type check for yield not yet implemented
     String source =
         lines(
             "var x = 0;",
@@ -1789,7 +1789,7 @@ public void testCallGenerator1() {
   }
 
   public void testCallGenerator2() {
-    this.mode = TypeInferenceMode.NEITHER; // type check for yield not yet implemented
+    this.mode = TypeInferenceMode.DISABLED; // type check for yield not yet implemented
     String source = lines(
             "function* f() {",
             "  while (true) {",
@@ -1902,19 +1902,19 @@ public void testAnonymousFunction4() throws Exception {
   }
 
   public void testClassMethod1() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source = "class C { m() { alert(1); } }; (new C).m();";
     assertNoPureCalls(source);
   }
 
   public void testClassMethod2() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source = "class C { m() { } }; (new C).m();";
     assertPureCallsMarked(source, ImmutableList.of("NEW STRING m"));
   }
 
   public void testClassMethod3() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     String source = "class C { m1() { } m2() { this.m1(); }}; (new C).m2();";
     assertPureCallsMarked(source, ImmutableList.of("this.m1", "NEW STRING m2"));
   }
diff --git a/test/com/google/javascript/jscomp/RemoveUnusedCodeClassPropertiesTest.java b/test/com/google/javascript/jscomp/RemoveUnusedCodeClassPropertiesTest.java
index e3e129a6e0e..921fe731416 100644
--- a/test/com/google/javascript/jscomp/RemoveUnusedCodeClassPropertiesTest.java
+++ b/test/com/google/javascript/jscomp/RemoveUnusedCodeClassPropertiesTest.java
@@ -79,8 +79,6 @@ public RemoveUnusedCodeClassPropertiesTest() {
     super(EXTERNS);
   }
 
-  @Override void checkMinimalExterns(Iterable<SourceFile> externs) {}
-
   @Override
   protected CompilerPass getProcessor(Compiler compiler) {
     return new RemoveUnusedCode.Builder(compiler)
@@ -97,7 +95,7 @@ protected void setUp() throws Exception {
     enableNormalize();
     enableGatherExternProperties();
     setAcceptedLanguage(LanguageMode.ECMASCRIPT_2017);
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
   }
 
   public void testSimple1() {
@@ -269,7 +267,7 @@ public void testPrototypeProps2() {
   }
 
   public void testConstructorProperty1() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     test(
         "/** @constructor */ function C() {} C.prop = 1;",
@@ -277,7 +275,7 @@ public void testConstructorProperty1() {
   }
 
   public void testConstructorProperty2() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     testSame(
         lines(
@@ -289,7 +287,7 @@ public void testConstructorProperty2() {
 
   public void testES6StaticProperty() {
     // TODO(bradfordcsmith): Neither type checker understands ES6 classes yet.
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
 
     test(
         "class C { static prop() {} }", // preserve newline
@@ -297,14 +295,14 @@ public void testES6StaticProperty() {
   }
 
   public void testES6StaticProperty2() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
 
     // TODO(bradfordcsmith): When NTI understands ES6 classes it will allow removal of `C.prop = 1`.
     testSame("class C {} C.prop = 1;");
   }
 
   public void testObjectDefineProperties1() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     testSame(
         lines(
@@ -315,7 +313,7 @@ public void testObjectDefineProperties1() {
   }
 
   public void testObjectDefineProperties2() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     test(
         lines(
@@ -327,7 +325,7 @@ public void testObjectDefineProperties2() {
   }
 
   public void testObjectDefineProperties3() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     test(
         lines(
@@ -344,7 +342,7 @@ public void testObjectDefineProperties3() {
 
   // side-effect in definition retains property definition, but doesn't count as a reference
   public void testObjectDefineProperties4() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     test(
         lines(
@@ -357,7 +355,7 @@ public void testObjectDefineProperties4() {
 
   // quoted properties retains property
   public void testObjectDefineProperties5() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     testSame(
         lines(
@@ -366,7 +364,7 @@ public void testObjectDefineProperties5() {
   }
 
   public void testObjectDefineProperties6() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     // an unknown destination object doesn't prevent removal.
     test(
@@ -375,7 +373,7 @@ public void testObjectDefineProperties6() {
   }
 
   public void testObjectDefineProperties7() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     test(
         lines(
@@ -387,7 +385,7 @@ public void testObjectDefineProperties7() {
   }
 
   public void testObjectDefineProperties8() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     test(
         lines(
@@ -399,7 +397,7 @@ public void testObjectDefineProperties8() {
   }
 
   public void testObjectDefinePropertiesQuotesPreventRemoval() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     testSame(
         lines(
@@ -410,7 +408,7 @@ public void testObjectDefinePropertiesQuotesPreventRemoval() {
   public void testObjectDefineProperties_used_setter_removed() {
     // TODO(bradfordcsmith): Either remove, fix this, or document it as a limitation of advanced
     // mode optimizations.
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     test(
         lines(
@@ -485,7 +483,7 @@ public void testEs6EnhancedObjLiteralsPropertyShorthand() {
   }
 
   public void testTranspiledEs6GettersRemoval() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     test(
         // This is the output of ES6->ES5 class getter converter.
         // See Es6ToEs3ConverterTest.testEs5GettersAndSettersClasses test method.
@@ -510,7 +508,7 @@ public void testTranspiledEs6GettersRemoval() {
   }
 
   public void testTranspiledEs6SettersRemoval() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     test(
         // This is the output of ES6->ES5 class setter converter.
         // See Es6ToEs3ConverterTest.testEs5GettersAndSettersClasses test method.
diff --git a/test/com/google/javascript/jscomp/RemoveUnusedCodeNameAnalyzerTest.java b/test/com/google/javascript/jscomp/RemoveUnusedCodeNameAnalyzerTest.java
index 08f91681dd2..4c206ad0cee 100644
--- a/test/com/google/javascript/jscomp/RemoveUnusedCodeNameAnalyzerTest.java
+++ b/test/com/google/javascript/jscomp/RemoveUnusedCodeNameAnalyzerTest.java
@@ -24,7 +24,7 @@
  * aka smartNamePass, which has now been removed.
  */
 
-public final class RemoveUnusedCodeNameAnalyzerTest extends TypeICompilerTestCase {
+public final class RemoveUnusedCodeNameAnalyzerTest extends CompilerTestCase {
 
   private static final String EXTERNS =
       lines(
@@ -73,7 +73,6 @@ protected CompilerPass getProcessor(Compiler compiler) {
   }
 
   private static class MarkNoSideEffectCallsAndRemoveUnusedCodeRunner implements CompilerPass {
-    VarCheck varCheck;
     MarkNoSideEffectCalls markNoSideEffectCalls;
     RemoveUnusedCode removeUnusedCode;
 
@@ -106,8 +105,6 @@ protected void setUp() throws Exception {
     setAcceptedLanguage(LanguageMode.ECMASCRIPT_2017);
     enableNormalize();
     enableGatherExternProperties();
-    // Change this for the test cases that require type information.
-    this.mode = TypeInferenceMode.NEITHER;
   }
 
   public void testDefaultingAssignmentWithAssignedProperty() {
diff --git a/test/com/google/javascript/jscomp/ReplaceCssNamesTest.java b/test/com/google/javascript/jscomp/ReplaceCssNamesTest.java
index 9091f782271..da2d14587db 100644
--- a/test/com/google/javascript/jscomp/ReplaceCssNamesTest.java
+++ b/test/com/google/javascript/jscomp/ReplaceCssNamesTest.java
@@ -136,8 +136,7 @@ private void doNotUseReplacementMap() {
     assertThat(cssNames).isEqualTo(expected);
   }
 
-  public void testDoNotUseReplacementMapOti() {
-    this.mode = TypeInferenceMode.OTI_ONLY;
+  public void testDoNotUseReplacementMap() {
     doNotUseReplacementMap();
   }
 
@@ -172,8 +171,7 @@ private void oneArgWithSimpleStringLiterals() {
     assertThat(cssNames).isEqualTo(expected);
   }
 
-  public void testOneArgWithSimpleStringLiteralsOti() {
-    this.mode = TypeInferenceMode.OTI_ONLY;
+  public void testOneArgWithSimpleStringLiterals() {
     oneArgWithSimpleStringLiterals();
   }
 
@@ -196,8 +194,7 @@ private void oneArgWithCompositeClassNames() {
     assertThat(cssNames).isEqualTo(expected);
   }
 
-  public void testOneArgWithCompositeClassNamesOti() {
-    this.mode = TypeInferenceMode.OTI_ONLY;
+  public void testOneArgWithCompositeClassNames() {
     oneArgWithCompositeClassNames();
   }
 
diff --git a/test/com/google/javascript/jscomp/ReplaceStringsTest.java b/test/com/google/javascript/jscomp/ReplaceStringsTest.java
index 11beea6119f..4dede320bad 100644
--- a/test/com/google/javascript/jscomp/ReplaceStringsTest.java
+++ b/test/com/google/javascript/jscomp/ReplaceStringsTest.java
@@ -91,7 +91,6 @@ protected CompilerOptions getOptions() {
   @Override
   protected void setUp() throws Exception {
     super.setUp();
-    this.mode = TypeInferenceMode.BOTH;
     enableNormalize();
     enableParseTypeInfo();
     functionsToInspect = defaultFunctionsToInspect;
@@ -382,9 +381,6 @@ public void testLoggerOnVar() {
   }
 
   public void testLoggerOnThis() {
-    // This fails in NTI because NTI doesn't specialize the type of THIS after the assignment;
-    // THIS remains unknown. Working as intended.
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testDebugStrings(
         "function f() {" +
         "  this.logger_ = goog.debug.Logger.getLogger('foo');" +
diff --git a/test/com/google/javascript/jscomp/ScopedAliasesTest.java b/test/com/google/javascript/jscomp/ScopedAliasesTest.java
index 68d566e1329..201e0714cb3 100644
--- a/test/com/google/javascript/jscomp/ScopedAliasesTest.java
+++ b/test/com/google/javascript/jscomp/ScopedAliasesTest.java
@@ -61,7 +61,7 @@ public ScopedAliasesTest() {
   @Override
   protected void setUp() throws Exception {
     super.setUp();
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     enableRunTypeCheckAfterProcessing();
   }
 
@@ -407,7 +407,7 @@ public void testObjectLiteralComputedPropertyNames() {
   }
 
   public void testJsDocNotIgnored() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     String externs =
         lines(
@@ -432,8 +432,7 @@ public void testJsDocNotIgnored() {
     test(
         externs(externs),
         srcs(js),
-        warningOtiNti(
-            TypeValidator.TYPE_MISMATCH_WARNING, NewTypeInference.INVALID_ARGUMENT_TYPE));
+        warning(TypeValidator.TYPE_MISMATCH_WARNING));
 
     js =
         lines(
@@ -447,8 +446,7 @@ public void testJsDocNotIgnored() {
     test(
         externs(externs),
         srcs(js),
-        warningOtiNti(
-            TypeValidator.TYPE_MISMATCH_WARNING, NewTypeInference.INVALID_ARGUMENT_TYPE));
+        warning(TypeValidator.TYPE_MISMATCH_WARNING));
   }
 
   public void testUsingObjectLiteralToEscapeScoping() {
@@ -578,7 +576,7 @@ public void testJsDocTypedef() {
   }
 
   public void testJsDocRecord() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     test(
         lines(
             "/** @const */ var ns = {};",
@@ -589,7 +587,7 @@ public void testJsDocRecord() {
         lines(
             "/** @const */ var ns = {};",
             "/** @type {{x: string}} */ ns.y = {'goog.Timer': 'x'};"),
-        warningOtiNti(TypeValidator.TYPE_MISMATCH_WARNING, NewTypeInference.MISTYPED_ASSIGN_RHS));
+        warning(TypeValidator.TYPE_MISMATCH_WARNING));
   }
 
   public void testArrayJsDoc() {
@@ -704,7 +702,7 @@ public void testIssue772() {
   }
 
   public void testInlineJsDoc() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     test(
         srcs(lines(
             "/** @const */ var ns = {};",
@@ -723,7 +721,7 @@ public void testInlineJsDoc() {
   }
 
   public void testInlineReturn() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     test(
         srcs(lines(
             "/** @const */ var ns = {};",
@@ -744,7 +742,7 @@ public void testInlineReturn() {
   }
 
   public void testInlineParam() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
     test(
         srcs(lines(
             "/** @const */ var ns = {};",
@@ -1069,7 +1067,7 @@ public void testObjectPattern() {
   }
 
   public void testTypeCheck() {
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
 
     test(
         lines(
@@ -1082,8 +1080,7 @@ public void testTypeCheck() {
             "/** @return {$jscomp.scope.F} */",
             "$jscomp.scope.createFoo = /** @return {$jscomp.scope.F} */ function() { return 1; };",
             "/** @constructor */ $jscomp.scope.F = /** @constructor */ function() { };"),
-        warningOtiNti(
-            TypeValidator.TYPE_MISMATCH_WARNING, NewTypeInference.RETURN_NONDECLARED_TYPE));
+        warning(TypeValidator.TYPE_MISMATCH_WARNING));
   }
 
   // Alias Recording Tests
diff --git a/test/com/google/javascript/jscomp/StrictModeCheckTest.java b/test/com/google/javascript/jscomp/StrictModeCheckTest.java
index ca40c0bf4d2..bd230364659 100644
--- a/test/com/google/javascript/jscomp/StrictModeCheckTest.java
+++ b/test/com/google/javascript/jscomp/StrictModeCheckTest.java
@@ -29,7 +29,6 @@ public StrictModeCheckTest() {
   protected void setUp() throws Exception {
     super.setUp();
     setAcceptedLanguage(LanguageMode.ECMASCRIPT_2017);
-    this.mode = TypeInferenceMode.OTI_ONLY;
   }
 
   @Override
@@ -104,7 +103,7 @@ public void testUnknownVariable3() {
   }
 
   public void testUnknownVariable4() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     testSameEs6Strict("function foo(a) { let b; a = b; }");
     testSameEs6Strict("function foo(a) { const b = 42; a = b; }");
   }
@@ -132,7 +131,7 @@ public void testArguments5() {
   }
 
   public void testArguments6() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     testSame("(() => arguments)();");
   }
 
@@ -179,7 +178,7 @@ public void testDeleteArgument() {
   public void testValidDelete() {
     testSame("var obj = { a: 0 }; delete obj.a;");
     testSame("var obj = { a: function() {} }; delete obj.a;");
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     testSameEs6Strict("var obj = { a(){} }; delete obj.a;");
     testSameEs6Strict("var obj = { a }; delete obj.a;");
   }
@@ -214,7 +213,7 @@ public void testDuplicateObjectLiteralKey() {
             "  set appData(data) { this.appData_ = data; }",
             "};"));
 
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     testError("var x = {a: 2, a(){}}", StrictModeCheck.DUPLICATE_OBJECT_KEY);
     testError("var x = {a, a(){}}", StrictModeCheck.DUPLICATE_OBJECT_KEY);
     testError("var x = {a(){}, a(){}}", StrictModeCheck.DUPLICATE_OBJECT_KEY);
@@ -238,7 +237,7 @@ public void testFunctionDecl() {
   }
 
   public void testClass() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     testSame(
         lines(
             "class A {",
@@ -334,7 +333,7 @@ public void testClass() {
   }
 
   public void testComputedPropInClass() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     testSame(
         lines(
             "class Example {",
@@ -344,7 +343,7 @@ public void testComputedPropInClass() {
   }
 
   public void testStaticAndNonstaticMethodWithSameName() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     testSame(
         lines(
             "class Example {",
@@ -354,7 +353,7 @@ public void testStaticAndNonstaticMethodWithSameName() {
   }
 
   public void testStaticAndNonstaticGetterWithSameName() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     testSame(
         lines(
             "class Example {",
@@ -364,7 +363,7 @@ public void testStaticAndNonstaticGetterWithSameName() {
   }
 
   public void testStaticAndNonstaticSetterWithSameName() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     testSame(
         lines(
             "class Example {",
@@ -374,7 +373,7 @@ public void testStaticAndNonstaticSetterWithSameName() {
   }
 
   public void testClassWithEmptyMembers() {
-    this.mode = TypeInferenceMode.NEITHER;
+    this.mode = TypeInferenceMode.DISABLED;
     testError("class Foo { dup() {}; dup() {}; }", StrictModeCheck.DUPLICATE_CLASS_METHODS);
   }
 
diff --git a/test/com/google/javascript/jscomp/TypeICompilerTestCase.java b/test/com/google/javascript/jscomp/TypeICompilerTestCase.java
index a2c4e10b914..0b7605b7506 100644
--- a/test/com/google/javascript/jscomp/TypeICompilerTestCase.java
+++ b/test/com/google/javascript/jscomp/TypeICompilerTestCase.java
@@ -15,13 +15,11 @@
  */
 package com.google.javascript.jscomp;
 
-import java.io.IOException;
 import java.util.List;
 import java.util.logging.Logger;
 
 /**
  * CompilerTestCase for passes that run after type checking and use type information.
- * Allows us to test those passes with both type checkers.
  *
  * @author dimvar@google.com (Dimitris Vardoulakis)
  */
@@ -31,25 +29,19 @@ public abstract class TypeICompilerTestCase extends CompilerTestCase {
       Logger.getLogger("com.google.javascript.jscomp.TypeICompilerTestCase");
 
   protected static enum TypeInferenceMode {
-    NEITHER,
-    OTI_ONLY,
-    NTI_ONLY,
-    BOTH;
+    DISABLED,
+    CHECKED;
 
-    boolean runsOTI() {
-      return this == OTI_ONLY || this == BOTH;
+    boolean runsTypeCheck() {
+      return this == CHECKED;
     }
 
-    boolean runsNTI() {
-      return this == NTI_ONLY || this == BOTH;
-    }
-
-    boolean runsNeither() {
-      return this == NEITHER;
+    boolean runsWithoutTypeCheck() {
+      return this == DISABLED;
     }
   }
 
-  protected TypeInferenceMode mode = TypeInferenceMode.BOTH;
+  protected TypeInferenceMode mode = TypeInferenceMode.CHECKED;
 
   public TypeICompilerTestCase() {
     super(MINIMAL_EXTERNS);
@@ -62,16 +54,9 @@ public TypeICompilerTestCase(String defaultExterns) {
   @Override
   protected void setUp() throws Exception {
     super.setUp();
-    this.mode = TypeInferenceMode.BOTH;
+    this.mode = TypeInferenceMode.CHECKED;
   }
 
-  // NOTE(aravindpg): the idea with these selective overrides is that every `test` call
-  // in a subclass must go through one and exactly one of the overrides here, which are
-  // the ones that actually run the test twice (once under OTI and once under NTI).
-  // The `test` methods in CompilerTestCase overload each other in complicated ways,
-  // and this is the minimal set of overrides (of visible methods) that essentially
-  // "post-dominates" any `test` call.
-
   @Override
   protected void testInternal(
       Externs externs,
@@ -79,16 +64,13 @@ protected void testInternal(
       Expected expected,
       Diagnostic diagnostic,
       List<Postcondition> postconditions) {
-    if (this.mode.runsOTI()) {
-      logger.info("Running with OTI");
-      testOTI(externs, js, expected, diagnostic, postconditions);
-    }
-    if (this.mode.runsNTI()) {
-      logger.info("Running with NTI");
-      checkMinimalExterns(externs.externs);
-      testNTI(externs, js, expected, diagnostic, postconditions);
+    if (this.mode.runsTypeCheck()) {
+      logger.info("Running with typechecking");
+      enableTypeCheck();
+      super.testInternal(externs, js, expected, diagnostic, postconditions);
+      disableTypeCheck();
     }
-    if (this.mode.runsNeither()) {
+    if (this.mode.runsWithoutTypeCheck()) {
       logger.info("Running without typechecking");
       super.testInternal(externs, js, expected, diagnostic, postconditions);
     }
@@ -97,110 +79,13 @@ protected void testInternal(
   @Override
   protected void testExternChanges(String extern, String input, String expectedExtern,
       DiagnosticType... warnings) {
-    if (this.mode.runsOTI()) {
+    if (this.mode.runsTypeCheck()) {
       enableTypeCheck();
       super.testExternChanges(extern, input, expectedExtern, warnings);
       disableTypeCheck();
     }
-    if (this.mode.runsNTI()) {
-      enableNewTypeInference();
-      super.testExternChanges(extern, input, expectedExtern, warnings);
-      disableNewTypeInference();
-    }
-    if (this.mode.runsNeither()) {
+    if (this.mode.runsWithoutTypeCheck()) {
       super.testExternChanges(extern, input, expectedExtern, warnings);
     }
   }
-
-  // Note: may be overridden to allow different externs if necessary.
-  void checkMinimalExterns(Iterable<SourceFile> externs) {
-    try {
-      for (SourceFile extern : externs) {
-        if (extern.getCode().contains(MINIMAL_EXTERNS)) {
-          return;
-        }
-      }
-    } catch (IOException e) {
-      throw new RuntimeException(e);
-    }
-    fail("NTI reqires at least the MINIMAL_EXTERNS");
-  }
-
-  private void testOTI(
-      Externs externs,
-      Sources js,
-      Expected expected,
-      Diagnostic diagnostic,
-      List<Postcondition> postconditions) {
-    TypeInferenceMode saved = this.mode;
-    this.mode = TypeInferenceMode.OTI_ONLY;
-    enableTypeCheck();
-    Diagnostic oti =
-        diagnostic instanceof OtiNtiDiagnostic ? ((OtiNtiDiagnostic) diagnostic).oti : diagnostic;
-    super.testInternal(externs, js, expected, oti, postconditions);
-    disableTypeCheck();
-    this.mode = saved;
-  }
-
-  private void testNTI(
-      Externs externs,
-      Sources js,
-      Expected expected,
-      Diagnostic diagnostic,
-      List<Postcondition> postconditions) {
-    /*
-    TypeInferenceMode saved = this.mode;
-    this.mode = TypeInferenceMode.NTI_ONLY;
-    enableNewTypeInference();
-    Diagnostic nti =
-        diagnostic instanceof OtiNtiDiagnostic ? ((OtiNtiDiagnostic) diagnostic).nti : diagnostic;
-    super.testInternal(externs, js, expected, nti, postconditions);
-    disableNewTypeInference();
-    this.mode = saved;
-    */
-  }
-
-  void testWarningOtiNti(
-      String js, DiagnosticType otiWarning, DiagnosticType ntiWarning) {
-    TypeInferenceMode saved = this.mode;
-    this.mode = TypeInferenceMode.OTI_ONLY;
-    testWarning(js, otiWarning);
-    /*
-    this.mode = TypeInferenceMode.NTI_ONLY;
-    testWarning(js, ntiWarning);
-    */
-    this.mode = saved;
-  }
-
-  @Override
-  protected Compiler getLastCompiler() {
-    switch (this.mode) {
-      case BOTH:
-        throw new AssertionError("getLastCompiler does not work correctly in BOTH mode.");
-      default:
-        return super.getLastCompiler();
-    }
-  }
-
-  // Helpers to test separate warnings/errors with OTI and NTI.
-
-  protected static OtiNtiDiagnostic warningOtiNti(DiagnosticType oti, DiagnosticType nti) {
-    return new OtiNtiDiagnostic(
-        oti != null ? warning(oti) : null, nti != null ? warning(nti) : null);
-  }
-
-  protected static OtiNtiDiagnostic diagnosticOtiNti(Diagnostic oti, Diagnostic nti) {
-    return new OtiNtiDiagnostic(oti, nti);
-  }
-
-  protected static class OtiNtiDiagnostic extends Diagnostic {
-    private final Diagnostic oti;
-    private final Diagnostic nti;
-
-    private OtiNtiDiagnostic(Diagnostic oti, Diagnostic nti) {
-      super(null, null, null);
-      this.oti = oti;
-      this.nti = nti;
-    }
-  }
 }
diff --git a/test/com/google/javascript/jscomp/lint/CheckNullableReturnTest.java b/test/com/google/javascript/jscomp/lint/CheckNullableReturnTest.java
index 506fe71c4d4..03946de3e94 100644
--- a/test/com/google/javascript/jscomp/lint/CheckNullableReturnTest.java
+++ b/test/com/google/javascript/jscomp/lint/CheckNullableReturnTest.java
@@ -75,9 +75,7 @@ public void testNullableReturn() {
   public void testNotNullableReturn()  {
     // Empty function body. Ignore this case. The remainder of the functions in
     // this test have non-empty bodies.
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testBodyOk("");
-    this.mode = TypeInferenceMode.BOTH;
 
     // Simple case.
     testBodyError("return {};");
@@ -98,7 +96,6 @@ public void testFinallyStatements() {
     testBodyOk("try { } finally { return null; }");
     testBodyOk("try { return {}; } finally { return null; }");
     testBodyOk("try { return null; } finally { return {}; }");
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testBodyError("try { } catch (e) { return null; } finally { return {}; }");
   }
 
@@ -124,7 +121,6 @@ public void testKnownWhileLoop() {
     testBodyError("while (0) {} return {}");
 
     // Not known.
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testBodyError("while(x) { return {}; }");
   }
 
@@ -189,7 +185,6 @@ public void testTryCatch() {
   }
 
   public void testNoExplicitReturn() {
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testError(lines(
         "/** @return {SomeType} */",
         "function f() {",
@@ -212,7 +207,6 @@ public void testNoWarningIfCanReturnNull() {
   }
 
   public void testNoWarningOnEmptyFunction() {
-    this.mode = TypeInferenceMode.OTI_ONLY;
     testOk(lines(
         "/** @return {SomeType} */",
         "function f() {}"));