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Testing Field Naming Policy Transformations in Google GSON

This test suite evaluates GSON’s field naming policies and serialization behavior. It validates different naming conventions and their impact on JSON output, ensuring proper field name transformations during serialization.

Test Coverage Overview

The test suite provides comprehensive coverage of GSON’s FieldNamingPolicy implementations.

Key areas tested include:

Identity preservation of field names
Upper camel case conversion
Upper camel case with spaces
Uppercase with underscores
Lowercase with underscores and dashes
Handling of leading underscores and annotated names

Implementation Analysis

The testing approach uses a TestNames class with various field naming patterns to verify serialization outcomes. Each test method focuses on a specific naming policy, using string comparison to validate JSON output format.

Implementation features:

GsonBuilder configuration for different naming policies
SerializedName annotation testing
Character replacement for consistent assertions

Technical Details

Testing tools and configuration:

JUnit framework for test execution
Google Truth assertion library
GSON library with GsonBuilder customization
Custom TestNames class with varied field naming patterns
SerializedName annotations for name overriding

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Isolated test methods for each naming policy
Consistent assertion patterns
Clear test case organization
Comprehensive edge case coverage
Proper use of suppression annotations with explanations

google/gson

gson/src/test/java/com/google/gson/functional/FieldNamingTest.java

            
/*
 * Copyright (C) 2011 Google Inc.
 *
 * 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.gson.functional;

import static com.google.common.truth.Truth.assertThat;
import static com.google.gson.FieldNamingPolicy.IDENTITY;
import static com.google.gson.FieldNamingPolicy.LOWER_CASE_WITH_DASHES;
import static com.google.gson.FieldNamingPolicy.LOWER_CASE_WITH_UNDERSCORES;
import static com.google.gson.FieldNamingPolicy.UPPER_CAMEL_CASE;
import static com.google.gson.FieldNamingPolicy.UPPER_CAMEL_CASE_WITH_SPACES;
import static com.google.gson.FieldNamingPolicy.UPPER_CASE_WITH_UNDERSCORES;

import com.google.gson.FieldNamingPolicy;
import com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.annotations.SerializedName;
import org.junit.Test;

public final class FieldNamingTest {
  @Test
  public void testIdentity() {
    Gson gson = getGsonWithNamingPolicy(IDENTITY);
    assertThat(gson.toJson(new TestNames()).replace('\"', '\''))
        .isEqualTo(
            "{'lowerCamel':1,'UpperCamel':2,'_lowerCamelLeadingUnderscore':3,"
                + "'_UpperCamelLeadingUnderscore':4,'lower_words':5,'UPPER_WORDS':6,"
                + "'annotatedName':7,'lowerId':8,'_9':9}");
  }

  @Test
  public void testUpperCamelCase() {
    Gson gson = getGsonWithNamingPolicy(UPPER_CAMEL_CASE);
    assertThat(gson.toJson(new TestNames()).replace('\"', '\''))
        .isEqualTo(
            "{'LowerCamel':1,'UpperCamel':2,'_LowerCamelLeadingUnderscore':3,"
                + "'_UpperCamelLeadingUnderscore':4,'Lower_words':5,'UPPER_WORDS':6,"
                + "'annotatedName':7,'LowerId':8,'_9':9}");
  }

  @Test
  public void testUpperCamelCaseWithSpaces() {
    Gson gson = getGsonWithNamingPolicy(UPPER_CAMEL_CASE_WITH_SPACES);
    assertThat(gson.toJson(new TestNames()).replace('\"', '\''))
        .isEqualTo(
            "{'Lower Camel':1,'Upper Camel':2,'_Lower Camel Leading Underscore':3,"
                + "'_ Upper Camel Leading Underscore':4,'Lower_words':5,'U P P E R_ W O R D S':6,"
                + "'annotatedName':7,'Lower Id':8,'_9':9}");
  }

  @Test
  public void testUpperCaseWithUnderscores() {
    Gson gson = getGsonWithNamingPolicy(UPPER_CASE_WITH_UNDERSCORES);
    assertThat(gson.toJson(new TestNames()).replace('\"', '\''))
        .isEqualTo(
            "{'LOWER_CAMEL':1,'UPPER_CAMEL':2,'_LOWER_CAMEL_LEADING_UNDERSCORE':3,"
                + "'__UPPER_CAMEL_LEADING_UNDERSCORE':4,'LOWER_WORDS':5,'U_P_P_E_R__W_O_R_D_S':6,"
                + "'annotatedName':7,'LOWER_ID':8,'_9':9}");
  }

  @Test
  public void testLowerCaseWithUnderscores() {
    Gson gson = getGsonWithNamingPolicy(LOWER_CASE_WITH_UNDERSCORES);
    assertThat(gson.toJson(new TestNames()).replace('\"', '\''))
        .isEqualTo(
            "{'lower_camel':1,'upper_camel':2,'_lower_camel_leading_underscore':3,"
                + "'__upper_camel_leading_underscore':4,'lower_words':5,'u_p_p_e_r__w_o_r_d_s':6,"
                + "'annotatedName':7,'lower_id':8,'_9':9}");
  }

  @Test
  public void testLowerCaseWithDashes() {
    Gson gson = getGsonWithNamingPolicy(LOWER_CASE_WITH_DASHES);
    assertThat(gson.toJson(new TestNames()).replace('\"', '\''))
        .isEqualTo(
            "{'lower-camel':1,'upper-camel':2,'_lower-camel-leading-underscore':3,"
                + "'_-upper-camel-leading-underscore':4,'lower_words':5,'u-p-p-e-r_-w-o-r-d-s':6,"
                + "'annotatedName':7,'lower-id':8,'_9':9}");
  }

  private static Gson getGsonWithNamingPolicy(FieldNamingPolicy fieldNamingPolicy) {
    return new GsonBuilder().setFieldNamingPolicy(fieldNamingPolicy).create();
  }

  // Suppress because fields are used reflectively, and the names are intentionally unconventional
  @SuppressWarnings({"unused", "MemberName", "ConstantField"})
  private static class TestNames {
    int lowerCamel = 1;
    int UpperCamel = 2;
    int _lowerCamelLeadingUnderscore = 3;
    int _UpperCamelLeadingUnderscore = 4;
    int lower_words = 5;
    int UPPER_WORDS = 6;

    @SerializedName("annotatedName")
    int annotated = 7;

    int lowerId = 8;
    int _9 = 9;
  }
}