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：
importstaticorg.junit.Assert.*; importjava.util.ArrayList; importjava.util.List; importorg.junit.Test; /*** @author javatutorials.co.in*/publicclassAssertionsTest { @TestpublicvoidtestAssertNull() { Stringstr=null; assertNull(str); } @TestpublicvoidtestAssertNotNull() { Stringstr="hello Java!!"; assertNotNull(str); } @TestpublicvoidtestAssertEqualsLong() { longlong1=2; longlong2=2; assertEquals(long1, long2); } @TestpublicvoidtestAssertEqualsDouble() { // test case is successfull as double1 and double 2// differ by 0.001 which is less than our specified deltadoubledouble1=1.236; doubledouble2=1.237; doubledelta=0.002; assertEquals(double1, double2, delta); } @TestpublicvoidtestAssertTrue() { List<String>list=newArrayList<String>(); assertTrue(list.isEmpty()); } @TestpublicvoidtestAssertFalse() { List<String>list=newArrayList<String>(); list.add("hello"); assertFalse(list.isEmpty()); } @TestpublicvoidtestAssertSame() { Stringstr1="hello world!!"; Stringstr2="hello world!!"; assertSame(str2, str1); } @TestpublicvoidtestAssertNotSame() { Stringstr1="hello world!!"; Stringstr3="hello Java!!"; assertNotSame(str1, str3); } }
样例输出
在eclipse Junit 窗口的输出如下：
附赠：
