三、Junit4 断言方法

     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 Assert Methods

Method	Description
assertNull(java.lang.Object object)	检查对象是否为空
assertNotNull(java.lang.Object object)	检查对象是否不为空
assertEquals(long expected, long actual)	检查long类型的值是否相等
assertEquals(double expected, double actual, double delta)	检查指定精度的double值是否相等
assertFalse(boolean condition)	检查条件是否为假
assertTrue(boolean condition)	检查条件是否为真
assertSame(java.lang.Object expected, java.lang.Object actual)	检查两个对象引用是否引用同一对象（即对象是否相等）
assertNotSame(java.lang.Object unexpected, java.lang.Object actual)	检查两个对象引用是否不引用统一对象(即对象不等)

 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 list = new ArrayList();
         assertTrue(list.isEmpty());
     }

     @Test
     public void testAssertFalse() {
         List list = new ArrayList();
         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：