Junit 4 斷言方法允許檢查測試方法的期望結果值和真實返回值。Junit的org.junit.Assert類提供了各種斷言方法來寫junit測試。這些方法被用來檢查方法的真實結果值和期望值。下列一些有用的斷言方法列表：

 Junit 4斷言方法樣例

AssertionsTest.java junit測試用例，顯示各種斷言方法：

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);
    }
}
 

樣例輸出

在eclipse Junit 視窗的輸出如下：

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