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Testing Java Util Class Serialization in Google Gson

This test suite evaluates Gson’s serialization and deserialization capabilities for Java utility classes, specifically focusing on Currency and Properties objects. The tests verify proper JSON conversion and handling of edge cases like null values while maintaining data integrity.

Test Coverage Overview

The test suite provides comprehensive coverage for Java utility class serialization, focusing on:

Currency object serialization and deserialization with currency code validation
Properties class JSON conversion with key-value pair preservation
Null value handling and empty object scenarios
String representation accuracy and format consistency

Implementation Analysis

The testing approach utilizes JUnit framework with Truth assertions for precise validation. The implementation follows a clear pattern of serialization-deserialization roundtrip testing, with each test case structured to verify both object conversion and data integrity maintenance.

Key patterns include setup isolation via @Before annotation and dedicated test methods for each utility class.

Technical Details

Testing Framework: JUnit 4
Assertion Library: Google Truth
Main Testing Tool: Gson instance
Test Setup: Individual Gson instance per test execution
Test Classes: CurrencyHolder (inner class), Properties

Best Practices Demonstrated

The test suite exemplifies several testing best practices including proper test isolation, clear test method naming, and comprehensive assertion coverage. Each test focuses on a single responsibility while maintaining a clear arrangement of setup, execution, and verification phases.

Isolated test setup using @Before
Specific test cases for null handling
Comprehensive assertion coverage
Clear test organization and structure

google/gson

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

            
/*
 * Copyright (C) 2015 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 java.util.Currency;
import java.util.Properties;
import org.junit.Before;
import org.junit.Test;

/** Functional test for Json serialization and deserialization for classes in java.util */
public class JavaUtilTest {
  private Gson gson;

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

  @Test
  public void testCurrency() {
    CurrencyHolder target = gson.fromJson("{'value':'USD'}", CurrencyHolder.class);
    assertThat(target.value.getCurrencyCode()).isEqualTo("USD");
    String json = gson.toJson(target);
    assertThat(json).isEqualTo("{\"value\":\"USD\"}");

    // null handling
    target = gson.fromJson("{'value':null}", CurrencyHolder.class);
    assertThat(target.value).isNull();
    assertThat(gson.toJson(target)).isEqualTo("{}");
  }

  private static class CurrencyHolder {
    Currency value;
  }

  @Test
  public void testProperties() {
    Properties props = gson.fromJson("{'a':'v1','b':'v2'}", Properties.class);
    assertThat(props.getProperty("a")).isEqualTo("v1");
    assertThat(props.getProperty("b")).isEqualTo("v2");
    String json = gson.toJson(props);
    assertThat(json).contains("\"a\":\"v1\"");
    assertThat(json).contains("\"b\":\"v2\"");
  }
}