Junit 4 断言方法允许检查测试方法的期望结果值和真实返回值。Junit的org.junit.Assert类提供了各种断言方法来写junit测试。这些方法被用来检查方法的真实结果值和期望值。下列一些有用的断言方法列表：

 Junit 4断言方法样例

AssertionsTest.java junit测试用例，显示各种断言方法：

import static org.junit.Assert.*;
 
import java.util.ArrayList;
import java.util.List;
 
import org.junit.Test;
 
/**
* @author javatutorials.co.in
*/
public class AssertionsTest {
 
    @Test
    public void testAssertNull() {
        String str = null;
        assertNull(str);
    }
 
    @Test
    public void testAssertNotNull() {
        String str = "hello Java!!";
        assertNotNull(str);
    }
 
    @Test
    public void testAssertEqualsLong() {
        long long1 = 2;
        long long2 = 2;
        assertEquals(long1, long2);
    }
 
    @Test
    public void testAssertEqualsDouble() {
        // test case is successfull as double1 and double 2
        // differ by 0.001 which is less than our specified delta
        double double1 = 1.236;
        double double2 = 1.237;
        double delta = 0.002;
        assertEquals(double1, double2, delta);
    }
 
    @Test
    public void testAssertTrue() {
        List<String> list = new ArrayList<String>();
        assertTrue(list.isEmpty());
    }
 
    @Test
    public void testAssertFalse() {
        List<String> list = new ArrayList<String>();
        list.add("hello");
        assertFalse(list.isEmpty());
    }
 
    @Test
    public void testAssertSame() {
        String str1 = "hello world!!";
        String str2 = "hello world!!";
        assertSame(str2, str1);
    }
 
    @Test
    public void testAssertNotSame() {
        String str1 = "hello world!!";
        String str3 = "hello Java!!";
        assertNotSame(str1, str3);
    }
}

样例输出

在eclipse Junit 窗口的输出如下：

源码下载

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教程目录导航

• Junit测试框架介绍

• Junit Eclipse教程

• Junit 4注解

• Junit 4断言方法（Assert methods）

• Junit 4参数化测试

• Junit 4测试套件(Test Suite)

• Junit 4忽略测试(Ignore Test)

• Junit 4超时测试（Timeout Test）

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