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Testing Print Formatting and Serialization Features in google/gson

This test suite evaluates the print formatting functionality in Google’s Gson library, focusing on JSON serialization behavior and whitespace handling. The tests verify compact formatting, null value handling, and serialization configuration options for the Gson parser.

Test Coverage Overview

The test suite provides comprehensive coverage of Gson’s print formatting capabilities.

Key areas tested include:

Compact formatting with no whitespace
Null value handling in JsonObjects
Serialization of null values with different configurations

The suite covers edge cases like empty objects and various primitive types through test helper classes.

Implementation Analysis

The testing approach utilizes JUnit 4 framework with focused test methods for specific formatting scenarios.

Notable patterns include:

Setup method initializing Gson instance
Use of Truth assertion library for readable assertions
Test helper classes for complex object structures

The implementation leverages GsonBuilder for configurable serialization behavior.

Technical Details

Testing infrastructure includes:

JUnit 4 testing framework
Google Truth assertion library
Gson and GsonBuilder APIs
Custom test type classes (BagOfPrimitives, Nested, etc.)
ArrayList for collection testing

Best Practices Demonstrated

The test suite exemplifies several testing best practices:

Clear test method naming conveying purpose
Proper test setup isolation using @Before
Focused test cases for specific functionality
Helper methods for common assertions
Comprehensive null handling verification

google/gson

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

            
/*
 * Copyright (C) 2008 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 com.google.gson.Gson;
import com.google.gson.GsonBuilder;
import com.google.gson.JsonObject;
import com.google.gson.common.TestTypes.BagOfPrimitives;
import com.google.gson.common.TestTypes.ClassWithTransientFields;
import com.google.gson.common.TestTypes.Nested;
import com.google.gson.common.TestTypes.PrimitiveArray;
import java.util.ArrayList;
import java.util.List;
import org.junit.Before;
import org.junit.Test;

/**
 * Functional tests for print formatting.
 *
 * @author Inderjeet Singh
 * @author Joel Leitch
 */
public class PrintFormattingTest {

  private Gson gson;

  @Before
  public void setUp() throws Exception {
    gson = new Gson();
  }

  @Test
  public void testCompactFormattingLeavesNoWhiteSpace() {
    List<Object> list = new ArrayList<>();
    list.add(new BagOfPrimitives());
    list.add(new Nested());
    list.add(new PrimitiveArray());
    list.add(new ClassWithTransientFields<>());

    String json = gson.toJson(list);
    assertContainsNoWhiteSpace(json);
  }

  @Test
  public void testJsonObjectWithNullValues() {
    JsonObject obj = new JsonObject();
    obj.addProperty("field1", "value1");
    obj.addProperty("field2", (String) null);
    String json = gson.toJson(obj);
    assertThat(json).contains("field1");
    assertThat(json).doesNotContain("field2");
  }

  @Test
  public void testJsonObjectWithNullValuesSerialized() {
    gson = new GsonBuilder().serializeNulls().create();
    JsonObject obj = new JsonObject();
    obj.addProperty("field1", "value1");
    obj.addProperty("field2", (String) null);
    String json = gson.toJson(obj);
    assertThat(json).contains("field1");
    assertThat(json).contains("field2");
  }

  @SuppressWarnings("LoopOverCharArray")
  private static void assertContainsNoWhiteSpace(String str) {
    for (char c : str.toCharArray()) {
      assertThat(Character.isWhitespace(c)).isFalse();
    }
  }
}