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Testing String Utility Methods in AndroidUtilCode

This test suite validates string manipulation utilities in the AndroidUtilCode library, covering essential string operations and transformations. The tests verify methods for string emptiness checking, case manipulation, and character conversion between full-width and half-width forms.

Test Coverage Overview

The test suite provides comprehensive coverage of StringUtils functionality, including empty string validation, case sensitivity checks, and string transformations.

Empty string validation with isEmpty(), isTrimEmpty(), and isSpace()
String comparison with equals() and equalsIgnoreCase()
Character case manipulation through upperFirstLetter() and lowerFirstLetter()
String transformation with reverse(), toDBC(), and toSBC() methods

Implementation Analysis

The testing approach utilizes JUnit’s assertion framework to validate string utility methods systematically. Each test method focuses on a specific string operation, employing multiple assertions to verify correct behavior.

The implementation follows AAA (Arrange-Act-Assert) pattern and leverages JUnit’s @Test annotations for test organization.

Technical Details

Testing Environment:

JUnit 4 testing framework
Static imports for assertion methods
BaseTest class extension for common test functionality
Java-based test implementation

Best Practices Demonstrated

The test suite exemplifies strong testing practices through methodical organization and thorough validation.

Comprehensive null case handling
Edge case testing for empty and whitespace strings
Consistent test method naming convention
Focused test methods with single responsibility
Clear assertion messages for debugging

blankj/androidutilcode

lib/utilcode/src/test/java/com/blankj/utilcode/util/StringUtilsTest.java

            
package com.blankj.utilcode.util;

import org.junit.Test;

import static org.junit.Assert.assertEquals;
import static org.junit.Assert.assertFalse;
import static org.junit.Assert.assertTrue;

/**
 * <pre>
 *     author: Blankj
 *     blog  : http://blankj.com
 *     time  : 2016/08/16
 *     desc  : test StringUtils
 * </pre>
 */
public class StringUtilsTest extends BaseTest {

    @Test
    public void isEmpty() {
        assertTrue(StringUtils.isEmpty(""));
        assertTrue(StringUtils.isEmpty(null));
        assertFalse(StringUtils.isEmpty(" "));
    }

    @Test
    public void isTrimEmpty() {
        assertTrue(StringUtils.isTrimEmpty(""));
        assertTrue(StringUtils.isTrimEmpty(null));
        assertTrue(StringUtils.isTrimEmpty(" "));
    }

    @Test
    public void isSpace() {
        assertTrue(StringUtils.isSpace(""));
        assertTrue(StringUtils.isSpace(null));
        assertTrue(StringUtils.isSpace(" "));
        assertTrue(StringUtils.isSpace("　 \n\t\r"));
    }

    @Test
    public void equals() {
        assertTrue(StringUtils.equals(null, null));
        assertTrue(StringUtils.equals("blankj", "blankj"));
        assertFalse(StringUtils.equals("blankj", "Blankj"));
    }

    @Test
    public void equalsIgnoreCase() {
        assertTrue(StringUtils.equalsIgnoreCase(null, null));
        assertFalse(StringUtils.equalsIgnoreCase(null, "blankj"));
        assertTrue(StringUtils.equalsIgnoreCase("blankj", "Blankj"));
        assertTrue(StringUtils.equalsIgnoreCase("blankj", "blankj"));
        assertFalse(StringUtils.equalsIgnoreCase("blankj", "blank"));
    }

    @Test
    public void null2Length0() {
        assertEquals("", StringUtils.null2Length0(null));
    }

    @Test
    public void length() {
        assertEquals(0, StringUtils.length(null));
        assertEquals(0, StringUtils.length(""));
        assertEquals(6, StringUtils.length("blankj"));
    }

    @Test
    public void upperFirstLetter() {
        assertEquals("Blankj", StringUtils.upperFirstLetter("blankj"));
        assertEquals("Blankj", StringUtils.upperFirstLetter("Blankj"));
        assertEquals("1Blankj", StringUtils.upperFirstLetter("1Blankj"));
    }

    @Test
    public void lowerFirstLetter() {
        assertEquals("blankj", StringUtils.lowerFirstLetter("blankj"));
        assertEquals("blankj", StringUtils.lowerFirstLetter("Blankj"));
        assertEquals("1blankj", StringUtils.lowerFirstLetter("1blankj"));
    }

    @Test
    public void reverse() {
        assertEquals("jknalb", StringUtils.reverse("blankj"));
        assertEquals("knalb", StringUtils.reverse("blank"));
        assertEquals("文中试测", StringUtils.reverse("测试中文"));
        assertEquals("", StringUtils.reverse(null));
    }

    @Test
    public void toDBC() {
        assertEquals(" ,.&", StringUtils.toDBC("　，．＆"));
    }

    @Test
    public void toSBC() {
        assertEquals("　，．＆", StringUtils.toSBC(" ,.&"));
    }
}