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初步认识JUnit
目前大多数的基于Java的企业应用软件，肯定少不了单元测试，程序员通过编写单元测试来验证自己程序的有效性；管理者通过持续自动的执行单元测试和分析单元测试覆盖率来确保软件本身的质量。可以说单元测试和集成测试在软件开发整个流程中占有举足轻重的地位。
单元测试，是指对软件中的最小可测试单元进行检查和验证。单元测试不是为了证明程序是对的，而是证明程序没有错。Java常用的单元测试框架有JUnit,TestNG,还有些MOCK框架，这里我们只来讲述JUnit。
JUnit的两种版本是JUnit 3.8和JUnit 4,前者使用反射，后者使用反射和注解。
1 package com.shop.web.test; 2 public class Calculator { 3 private static double result = 0.0; 4 public void add(double num) { 5 result = result + num; 6 } 7 public void substract(double num) { 8 result = result - num; 9 } 10 public void multiply(double num) { 11 result = result * num; 12 } 13 public void divide(double num) { 14 if (num != 0) { 15 result = result / num; 16 } else { 17 result = result; 18 } 19 } 20 // 清零 21 public void clear() { 22 result = 0; 23 } 24 public double getResult() { 25 return result; 26 } 27 }
CalculatorTest.java
1 package com.shop.web.test; 2 import junit.framework.TestCase; 3 public class CalculatorTest extends TestCase { 4 private static Calculator calculator = new Calculator(); 5 6 @Override 7 protected void setUp() throws Exception { 8 System.out.println("JUnit initialize the fixture state by overriding setup "); 9 calculator.clear(); 10 } 11 @Override 12 protected void tearDown() throws Exception { 13 System.out.println("JUnit clean-up after a test by overriding tearDown "); 14 calculator.clear(); 15 } 16 public void testAdd() { 17 System.out.println("add result:" + calculator.getResult()); 18 calculator.add(10.1); 19 assertEquals(10.1, calculator.getResult()); 20 } 21 public void testSubstract() { 22 System.out.println("substract result:" + calculator.getResult()); 23 calculator.add(10.1); 24 calculator.substract(2); 25 assertEquals(8.1, calculator.getResult()); 26 } 27 public void testMultiply() { 28 System.out.println("multiply result:" + calculator.getResult()); 29 calculator.add(12); 30 calculator.multiply(12); 31 assertEquals(144.0, calculator.getResult()); 32 } 33 public void testDivide() { 34 System.out.println("divide result:" + calculator.getResult()); 35 calculator.add(12); 36 calculator.divide(12); 37 assertEquals(1.0, calculator.getResult()); 38 } 39 }
绿条代表程序没有错误
1 public abstract class TestCase extends Assert implements Test 2 A test case defines the fixture to run multiple tests. 3 To define a test case 4 1) implement a subclass of TestCase 5 2) define instance variables that store the state of the fixture 6 3) initialize the fixture state by overriding setUp 7 4) clean-up after a test by overriding tearDown. 8 Each test runs in its own fixture so there can be no side effects among test runs
1 JUnit initialize the fixture state by overriding setup 2 add result:0.0 3 JUnit clean-up after a test by overriding tearDown 4 JUnit initialize the fixture state by overriding setup 5 substract result:0.0 6 JUnit clean-up after a test by overriding tearDown 7 JUnit initialize the fixture state by overriding setup 8 multiply result:0.0 9 JUnit clean-up after a test by overriding tearDown 10 JUnit initialize the fixture state by overriding setup 11 divide result:0.0 12 JUnit clean-up after a test by overriding tearDown
1 public class CalculatorTest4 { 2 private static Calculator calculator = new Calculator(); 3 4 @Before 5 public void setUp() throws Exception { 6 System.out.println("JUnit initialize the fixture state by overriding setup "); 7 calculator.clear(); 8 } 9 @After 10 public void tearDown() throws Exception { 11 System.out.println("JUnit clean-up after a test by overriding tearDown "); 12 calculator.clear(); 13 } 14 @Test 15 public void add() { 16 System.out.println("add result:" + calculator.getResult()); 17 calculator.add(10.1); 18 assertEquals(10.1, calculator.getResult()); 19 }
4、@Test(expected=*.class)
在JUnit4.0之前，对错误的测试，我们只能通过fail来产生一个错误，并在try块里面assertTrue（true）来测试。现在，通过@Test元数据中的expected属性。expected属性的值是一个异常的类型，用来检查抛出预期异常。
1 @Test(expected=ArithmeticException.class) 2 public void divide(){ 3 int i = 2/0; 4 }
5、@Test(timeout=xxx):
该元数据传入了一个时间（毫秒）给测试方法，
如果测试方法在制定的时间之内没有运行完，则测试也失败。
@Test(timeout=1) public void count(){ for (int i = 0; i < 1000000000; i++) { System.out.println(i); } }
1 @Ignore("此方法现在不需要") 2 @Test 3 public void ignore(){ 4 System.out.println("不需要"); 5 }
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原文地址：http://www.cnblogs.com/drubber/p/5791640.html
