feat: add Type#isNever()

Closes #1303
dsherret · Sep 3, 2022 · ac0db0d · ac0db0d
1 parent f1d5c43
commit ac0db0d
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Showing 5 changed files with 30 additions and 0 deletions.
diff --git a/deno/ts_morph.d.ts b/deno/ts_morph.d.ts
@@ -10123,6 +10123,8 @@ export declare class Type<TType extends ts.Type = ts.Type> {
   isAnonymous(): boolean;
   /** Gets if this is an any type. */
   isAny(): boolean;
+  /** Gets if this is a never type. */
+  isNever(): boolean;
   /** Gets if this is an array type. */
   isArray(): boolean;
   /** Gets if this is a readonly array type. */

diff --git a/deno/ts_morph.js b/deno/ts_morph.js
@@ -17980,6 +17980,9 @@ class Type {
     isAny() {
         return this._hasTypeFlag(TypeFlags.Any);
     }
+    isNever() {
+        return this._hasTypeFlag(TypeFlags.Never);
+    }
     isArray() {
         const symbol = this.getSymbol();
         if (symbol == null)

diff --git a/packages/ts-morph/lib/ts-morph.d.ts b/packages/ts-morph/lib/ts-morph.d.ts
@@ -10123,6 +10123,8 @@ export declare class Type<TType extends ts.Type = ts.Type> {
   isAnonymous(): boolean;
   /** Gets if this is an any type. */
   isAny(): boolean;
+  /** Gets if this is a never type. */
+  isNever(): boolean;
   /** Gets if this is an array type. */
   isArray(): boolean;
   /** Gets if this is a readonly array type. */

diff --git a/packages/ts-morph/src/compiler/types/Type.ts b/packages/ts-morph/src/compiler/types/Type.ts
@@ -379,6 +379,13 @@ export class Type<TType extends ts.Type = ts.Type> {
     return this._hasTypeFlag(TypeFlags.Any);
   }
 
+  /**
+   * Gets if this is a never type.
+   */
+  isNever() {
+    return this._hasTypeFlag(TypeFlags.Never);
+  }
+
   /**
    * Gets if this is an array type.
    */

diff --git a/packages/ts-morph/src/tests/compiler/type/typeTests.ts b/packages/ts-morph/src/tests/compiler/type/typeTests.ts
@@ -54,6 +54,7 @@ let genericArrayType: Array<string>;
 let arrayType: string[];
 let readonlyArrayType: readonly string[];
 let explicitReadonlyArrayType: ReadonlyArray<string>;
+let neverType: never;
 let arrayTypeOfTuples: [string][];
 let undefinedType: undefined;
 let classType: MyClass;
@@ -139,6 +140,21 @@ let unknownType: unknown;
       });
     });
 
+    describe(nameof<Type>("isNever"), () => {
+      function doTest(typeName: string, expected: boolean) {
+        expect(typesByName[typeName].isNever()).to.equal(expected);
+      }
+
+      it("should be when never", () => {
+        doTest("neverType", true);
+      });
+
+      it("should not be when not never", () => {
+        doTest("anyType", false);
+        doTest("stringType", false);
+      });
+    });
+
     describe(nameof<Type>("isBoolean"), () => {
       function doTest(typeName: string, expected: boolean) {
         expect(typesByName[typeName].isBoolean()).to.equal(expected);