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Validating ISO8601 Date Format Operations in google/gson

This test suite validates the ISO8601Utils class in the Google Gson library, focusing on date formatting and parsing functionality according to the ISO 8601 standard. The tests cover various date format scenarios including timezone handling, millisecond precision, and error validation.

Test Coverage Overview

The test suite provides comprehensive coverage of ISO8601 date formatting and parsing capabilities.

Key areas tested include:

Basic date format string generation
Millisecond precision handling
Timezone conversion and formatting
Date parsing with various formats
Invalid date/time validation

Implementation Analysis

The testing approach uses JUnit framework with systematic validation of both valid and invalid date scenarios. The implementation leverages Truth assertions for precise comparisons and demonstrates thorough error handling verification.

Testing patterns include:

Calendar-based date manipulation
Timezone-aware testing
Exception validation for invalid inputs
Parse position handling

Technical Details

Testing infrastructure includes:

JUnit test framework
Google Truth assertion library
GregorianCalendar for date manipulation
Custom UTC timezone handling
ParsePosition for granular parsing control

Best Practices Demonstrated

The test suite exemplifies high-quality testing practices through methodical organization and comprehensive coverage.

Notable practices include:

Isolated test methods with clear purpose
Thorough edge case handling
Proper test method naming
Consistent assertion patterns
Effective use of helper methods

google/gson

gson/src/test/java/com/google/gson/internal/bind/util/ISO8601UtilsTest.java

            
/*
 * Copyright (C) 2020 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.internal.bind.util;

import static com.google.common.truth.Truth.assertThat;
import static org.junit.Assert.assertThrows;

import java.text.ParseException;
import java.text.ParsePosition;
import java.util.Calendar;
import java.util.Date;
import java.util.GregorianCalendar;
import java.util.Locale;
import java.util.TimeZone;
import org.junit.Test;

@SuppressWarnings("MemberName") // class name
public class ISO8601UtilsTest {

  private static TimeZone utcTimeZone() {
    return TimeZone.getTimeZone("UTC");
  }

  private static GregorianCalendar createUtcCalendar() {
    TimeZone utc = utcTimeZone();
    GregorianCalendar calendar = new GregorianCalendar(utc);
    // Calendar was created with current time, must clear it
    calendar.clear();
    return calendar;
  }

  @Test
  public void testDateFormatString() {
    GregorianCalendar calendar = new GregorianCalendar(utcTimeZone(), Locale.US);
    // Calendar was created with current time, must clear it
    calendar.clear();
    calendar.set(2018, Calendar.JUNE, 25);
    Date date = calendar.getTime();
    String dateStr = ISO8601Utils.format(date);
    String expectedDate = "2018-06-25T00:00:00Z";
    assertThat(dateStr).isEqualTo(expectedDate);
  }

  @Test
  @SuppressWarnings("JavaUtilDate")
  public void testDateFormatWithMilliseconds() {
    long time = 1530209176870L;
    Date date = new Date(time);
    String dateStr = ISO8601Utils.format(date, true);
    String expectedDate = "2018-06-28T18:06:16.870Z";
    assertThat(dateStr).isEqualTo(expectedDate);
  }

  @Test
  @SuppressWarnings("JavaUtilDate")
  public void testDateFormatWithTimezone() {
    long time = 1530209176870L;
    Date date = new Date(time);
    String dateStr = ISO8601Utils.format(date, true, TimeZone.getTimeZone("Brazil/East"));
    String expectedDate = "2018-06-28T15:06:16.870-03:00";
    assertThat(dateStr).isEqualTo(expectedDate);
  }

  @Test
  @SuppressWarnings("UndefinedEquals")
  public void testDateParseWithDefaultTimezone() throws ParseException {
    String dateStr = "2018-06-25";
    Date date = ISO8601Utils.parse(dateStr, new ParsePosition(0));
    Date expectedDate = new GregorianCalendar(2018, Calendar.JUNE, 25).getTime();
    assertThat(date).isEqualTo(expectedDate);
  }

  @Test
  public void testDateParseInvalidDay() {
    String dateStr = "2022-12-33";
    assertThrows(ParseException.class, () -> ISO8601Utils.parse(dateStr, new ParsePosition(0)));
  }

  @Test
  public void testDateParseInvalidMonth() {
    String dateStr = "2022-14-30";
    assertThrows(ParseException.class, () -> ISO8601Utils.parse(dateStr, new ParsePosition(0)));
  }

  @Test
  @SuppressWarnings("UndefinedEquals")
  public void testDateParseWithTimezone() throws ParseException {
    String dateStr = "2018-06-25T00:00:00-03:00";
    Date date = ISO8601Utils.parse(dateStr, new ParsePosition(0));
    GregorianCalendar calendar = createUtcCalendar();
    calendar.set(2018, Calendar.JUNE, 25, 3, 0);
    Date expectedDate = calendar.getTime();
    assertThat(date).isEqualTo(expectedDate);
  }

  @Test
  @SuppressWarnings("UndefinedEquals")
  public void testDateParseSpecialTimezone() throws ParseException {
    String dateStr = "2018-06-25T00:02:00-02:58";
    Date date = ISO8601Utils.parse(dateStr, new ParsePosition(0));
    GregorianCalendar calendar = createUtcCalendar();
    calendar.set(2018, Calendar.JUNE, 25, 3, 0);
    Date expectedDate = calendar.getTime();
    assertThat(date).isEqualTo(expectedDate);
  }

  @Test
  public void testDateParseInvalidTime() {
    String dateStr = "2018-06-25T61:60:62-03:00";
    assertThrows(ParseException.class, () -> ISO8601Utils.parse(dateStr, new ParsePosition(0)));
  }
}