[ggj][engx] fix: handle post-digit caps, add test, and robustify JavaStyle

src/main/java/com/google/api/generator/gapic/utils/JavaStyle.java

@@ -15,25 +15,50 @@
 package com.google.api.generator.gapic.utils;
 
 import com.google.common.base.CaseFormat;
+import com.google.common.base.Strings;
+import java.util.stream.IntStream;
 
 public class JavaStyle {
   private static final String UNDERSCORE = "_";
 
   public static String toLowerCamelCase(String s) {
+    if (Strings.isNullOrEmpty(s)) {
+      return s;
+    }
+
     if (s.indexOf(UNDERSCORE) >= 0) {
       s = CaseFormat.LOWER_UNDERSCORE.to(CaseFormat.UPPER_CAMEL, s);
     }
-    return String.format("%s%s", s.substring(0, 1).toLowerCase(), s.substring(1));
+    return capitalizeLettersAfterDigits(
+        String.format("%s%s", s.substring(0, 1).toLowerCase(), s.substring(1)));
   }
 
   public static String toUpperCamelCase(String s) {
+    if (Strings.isNullOrEmpty(s)) {
+      return s;
+    }
+
     if (s.indexOf(UNDERSCORE) >= 0) {
       s = CaseFormat.LOWER_UNDERSCORE.to(CaseFormat.UPPER_CAMEL, s);
     }
-    return String.format("%s%s", s.substring(0, 1).toUpperCase(), s.substring(1));
+    return capitalizeLettersAfterDigits(
+        String.format("%s%s", s.substring(0, 1).toUpperCase(), s.substring(1)));
   }
 
   public static String toUpperSnakeCase(String s) {
     return CaseFormat.UPPER_CAMEL.to(CaseFormat.UPPER_UNDERSCORE, toUpperCamelCase(s));
   }
+
+  private static String capitalizeLettersAfterDigits(String s) {
+    return IntStream.range(0, s.length())
+        .collect(
+            StringBuilder::new,
+            (sb, i) ->
+                sb.append(
+                    i > 0 && Character.isDigit(s.charAt(i - 1))
+                        ? Character.toUpperCase(s.charAt(i))
+                        : s.charAt(i)),
+            StringBuilder::append)
+        .toString();
+  }
 }

src/test/java/com/google/api/generator/gapic/BUILD.bazel

@@ -6,5 +6,6 @@ filegroup(
         "//src/test/java/com/google/api/generator/gapic/composer:composer_files",
         "//src/test/java/com/google/api/generator/gapic/model:model_files",
         "//src/test/java/com/google/api/generator/gapic/protoparser:protoparser_files",
+        "//src/test/java/com/google/api/generator/gapic/utils:utils_files",
     ],
 )

src/test/java/com/google/api/generator/gapic/utils/BUILD.bazel

@@ -0,0 +1,21 @@
+package(default_visibility = ["//visibility:public"])
+
+TESTS = [
+    "JavaStyleTest",
+]
+
+filegroup(
+    name = "utils_files",
+    srcs = ["{0}.java".format(f) for f in TESTS],
+)
+
+[java_test(
+    name = test_name,
+    srcs = ["{0}.java".format(test_name)],
+    test_class = "com.google.api.generator.gapic.utils.{0}".format(test_name),
+    deps = [
+        "//src/main/java/com/google/api/generator/gapic/utils",
+        "@com_google_truth_truth//jar",
+        "@junit_junit//jar",
+    ],
+) for test_name in TESTS]

src/test/java/com/google/api/generator/gapic/utils/JavaStyleTest.java

@@ -0,0 +1,114 @@
+// Copyright 2020 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package com.google.api.generator.gapic.utils;
+
+import static com.google.common.truth.Truth.assertThat;
+import static junit.framework.Assert.assertEquals;
+
+import org.junit.Test;
+
+public class JavaStyleTest {
+  @Test
+  public void emptyOrNull() {
+    String value = "";
+    assertEquals("", JavaStyle.toLowerCamelCase(value));
+    assertEquals("", JavaStyle.toUpperCamelCase(value));
+
+    value = null;
+    assertThat(JavaStyle.toLowerCamelCase(value)).isNull();
+    assertThat(JavaStyle.toUpperCamelCase(value)).isNull();
+  }
+
+  @Test
+  public void singleWord() {
+    String value = "dog";
+    assertEquals("dog", JavaStyle.toLowerCamelCase(value));
+    assertEquals("Dog", JavaStyle.toUpperCamelCase(value));
+  }
+
+  @Test
+  public void fromLowerSnake() {
+    String value = "factory_decorator_delegate_impl";
+    assertEquals("factoryDecoratorDelegateImpl", JavaStyle.toLowerCamelCase(value));
+    assertEquals("FactoryDecoratorDelegateImpl", JavaStyle.toUpperCamelCase(value));
+  }
+
+  @Test
+  public void fromUpperSnake() {
+    String value = "FACTORY_DECORATOR_DELEGATE_IMPL";
+    assertEquals("factoryDecoratorDelegateImpl", JavaStyle.toLowerCamelCase(value));
+    assertEquals("FactoryDecoratorDelegateImpl", JavaStyle.toUpperCamelCase(value));
+  }
+
+  @Test
+  public void fromLowerCamelCase() {
+    String value = "factoryDecoratorDelegateImpl";
+    assertEquals("factoryDecoratorDelegateImpl", JavaStyle.toLowerCamelCase(value));
+    assertEquals("FactoryDecoratorDelegateImpl", JavaStyle.toUpperCamelCase(value));
+  }
+
+  @Test
+  public void fromUpperCamelCase() {
+    String value = "FactoryDecoratorDelegateImpl";
+    assertEquals("factoryDecoratorDelegateImpl", JavaStyle.toLowerCamelCase(value));
+    assertEquals("FactoryDecoratorDelegateImpl", JavaStyle.toUpperCamelCase(value));
+  }
+
+  @Test
+  public void wordAndNumber() {
+    String value = "dog2";
+    assertEquals("dog2", JavaStyle.toLowerCamelCase(value));
+    assertEquals("Dog2", JavaStyle.toUpperCamelCase(value));
+    value = "dog_2";
+    assertEquals("dog2", JavaStyle.toLowerCamelCase(value));
+    assertEquals("Dog2", JavaStyle.toUpperCamelCase(value));
+  }
+
+  @Test
+  public void upperWordAndNumber() {
+    String value = "Dog_v2";
+    assertEquals("dogV2", JavaStyle.toLowerCamelCase(value));
+    assertEquals("DogV2", JavaStyle.toUpperCamelCase(value));
+  }
+
+  @Test
+  public void upperWordAndCharsAfterDigit() {
+    String value = "dogV2cc";
+    assertEquals("dogV2Cc", JavaStyle.toLowerCamelCase(value));
+    assertEquals("DogV2Cc", JavaStyle.toUpperCamelCase(value));
+
+    value = "dogv2_cc";
+    assertEquals("dogv2Cc", JavaStyle.toLowerCamelCase(value));
+    assertEquals("Dogv2Cc", JavaStyle.toUpperCamelCase(value));
+
+    value = "dog_v2_cc";
+    assertEquals("dogV2Cc", JavaStyle.toLowerCamelCase(value));
+    assertEquals("DogV2Cc", JavaStyle.toUpperCamelCase(value));
+
+    value = "foo1bar2car3";
+    assertEquals("foo1Bar2Car3", JavaStyle.toLowerCamelCase(value));
+    assertEquals("Foo1Bar2Car3", JavaStyle.toUpperCamelCase(value));
+  }
+
+  @Test
+  public void acronyms() {
+    String value = "iam_http_xml_dog";
+    assertEquals("iamHttpXmlDog", JavaStyle.toLowerCamelCase(value));
+    assertEquals("IamHttpXmlDog", JavaStyle.toUpperCamelCase(value));
+    value = "IAM_HTTP_XML_DOG";
+    assertEquals("iamHttpXmlDog", JavaStyle.toLowerCamelCase(value));
+    assertEquals("IamHttpXmlDog", JavaStyle.toUpperCamelCase(value));
+  }
+}