JUnit110413: JUnit快速入门注记

JUnit110413: JUnit快速入门注记


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Blog    http://zcatt.blog.chinaunix.net
 
内容提要
通过一个实例快速入门JUnit4.以供备忘和参考。

声明
仅限学习交流，禁止商业用途。转载需注明出处。

版本记录
Date        Ver        Note
2011-04-13    0.1        Draft.  zcatt, Beijing
 
JUnit4中广泛的使用了annotation(注记), 简化了test的编写. 下面首先以一个例子介绍JUnit的使用, 随后汇总JUnit中一些主要的annotation. 本文的例子主要取材于[2], 致谢.

环境的配置
=======================

这里以Windows cmdline为例介绍. IDE中,尤其是eclipse中的junit使用很是便利,无需赘述.
下载junit, 放到一个目录中, 并设定CLASSPATH.

本例,

d:\JavaLib\junit-4.8.2.jar

设置环境变量

CLASSPATH=.;d:\JavaLib\junit-4.8.2.jar

编译源码
=======================

javac编译,

javac

本例, 两个源码文件calculator.java和calculatorTest.java, 假设位于E:\Test.

E:\Test>javac calculator.java calculatorTest.java

测试
=======================

执行测试,

java org.junit.runner.JUnitCore

本例,

E:\Test>java org.junit.runner.JUnitCore calculatorTest
JUnit version 4.8.2
..EI..E
Time: 1.031
There were 2 failures:
1) testSubstract(calculatorTest)
java.lang.AssertionError: expected:<8> but was:<9>
at org.junit.Assert.fail(Assert.java:91)
at org.junit.Assert.failNotEquals(Assert.java:645)
at org.junit.Assert.assertEquals(Assert.java:126)
at org.junit.Assert.assertEquals(Assert.java:470)
at org.junit.Assert.assertEquals(Assert.java:454)
at calculatorTest.testSubstract(calculatorTest.java:30)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.RunBefores.evaluate(RunBefores.java:28)
at org.junit.runners.BlockJUnit4ClassRunner.runNotIgnored(BlockJUnit4ClassRunner.java:79)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:71)
at org.junit.runners.BlockJUnit4ClassRunner.runChild(BlockJUnit4ClassRunner.java:49)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
at org.junit.runners.Suite.runChild(Suite.java:128)
at org.junit.runners.Suite.runChild(Suite.java:24)
at org.junit.runners.ParentRunner$3.run(ParentRunner.java:193)
at org.junit.runners.ParentRunner$1.schedule(ParentRunner.java:52)
at org.junit.runners.ParentRunner.runChildren(ParentRunner.java:191)
at org.junit.runners.ParentRunner.access$000(ParentRunner.java:42)
at org.junit.runners.ParentRunner$2.evaluate(ParentRunner.java:184)
at org.junit.runners.ParentRunner.run(ParentRunner.java:236)
at org.junit.runner.JUnitCore.run(JUnitCore.java:157)
at org.junit.runner.JUnitCore.run(JUnitCore.java:136)
at org.junit.runner.JUnitCore.run(JUnitCore.java:117)
at org.junit.runner.JUnitCore.runMain(JUnitCore.java:98)
at org.junit.runner.JUnitCore.runMainAndExit(JUnitCore.java:53)
at org.junit.runner.JUnitCore.main(JUnitCore.java:45)
2) testSquareRoot(calculatorTest)
java.lang.Exception: test timed out after 1000 milliseconds
at calculator.squareRoot(calculator.java:19)
at calculatorTest.testSquareRoot(calculatorTest.java:47)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:39)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:25)
at java.lang.reflect.Method.invoke(Method.java:597)
at org.junit.runners.model.FrameworkMethod$1.runReflectiveCall(FrameworkMethod.java:44)
at org.junit.internal.runners.model.ReflectiveCallable.run(ReflectiveCallable.java:15)
at org.junit.runners.model.FrameworkMethod.invokeExplosively(FrameworkMethod.java:41)
at org.junit.internal.runners.statements.InvokeMethod.evaluate(InvokeMethod.java:20)
at org.junit.internal.runners.statements.FailOnTimeout$1.run(FailOnTimeout.java:28)

FAILURES!!!
Tests run: 4,  Failures: 2

E:\Test>

测试结果中, E代表error, I代表ignore.

本例源码文件

//calculator.java
public class calculator {
    private static int result; // 静态变量，用于存储运行结果
    public void add(int n) {
        result = result + n;
    }
    public void substract(int n) {
        result = result - 1;  //Bug: 正确的应该是 result =result-n
    }
    public void multiply(int n) {
    }         // 此方法尚未写好
    public void divide(int n) {
        result = result / n;
    }
    public void square(int n) {
        result = n * n;
    }
    public void squareRoot(int n) {
        for (; ;) ;            //Bug : 死循环
    }
    public void clear() {     // 将结果清零
        result = 0;
    }
    public int getResult() {
        return result;
    }
}

//calculatorTest.java
import static org.junit.Assert.*;

import org.junit.Before;
import org.junit.Test;
import org.junit.Ignore;


public class calculatorTest {

    private static calculator cal = new calculator();

    @Before
    public void setUp() throws Exception {
        cal.clear();
    }

    @Test
    public void testAdd() {
        cal.add(2);
        cal.add(3);
        assertEquals(5, cal.getResult());

    }

    @Test
    public void testSubstract() {
           cal.add(10);
           cal.substract(2);
           assertEquals(8, cal.getResult());
     }

    @Ignore("Multiply() Not yet implemented")
    @Test
    public void testMultiply() {
    }

    @Test
    public void testDivide() {
        cal.add(8);
        cal.divide(2);
        assertEquals(4, cal.getResult());
    }

    @Test(timeout=1000)
    public void testSquareRoot() {
        cal.squareRoot(4);
        assertEquals(2, cal.getResult());
    }

}

JUnit4中的annotation
=======================
JUnit4使用annotation来发现要测试的方法.而以前的JUnit版本使用前缀test的signature辨别方式发现测试方法.

罗列一些常用的annotation:

@Test, 是测试方法
@Test(timeout=num_ms), 若超时, 则认为error
@Ignore, 忽略这个测试方法

@Before, 类似以前的setUp(), 是每个测试方法执行前都要运行的fixture. 可以修饰多个方法, 但多个方法间执行的次序不定.
@After,  类似以前的tearDown(), 是每个测试方法执行后都要运行的fixture.  可以修饰多个方法, 但多个方法间执行的次序不定.

@BeforeClass, 是每个测试类执行前都要运行的fixture, 仅执行一次. 只可修饰一个public static方法.
@AfterClass, 是每个测试类执行后都要运行的fixture, 仅执行一次.  只可修饰一个public static方法.

@RunWith(TestClassRunner.class), 修饰test class, 指定runner. 如不指定RunWith, 则默认runner是org.junit.internal.runners.TestClassRunner.

@Parameters, 需要输入多组数据反复测试时, 可以使用@Parameters, 预先定义好这些数据, JUnit的org.junit.runners.Parameterized这个runner会自动喂给测试. @Parameters用于修饰返回这些预定义数据的public static方法, 而且这个方法必须返回Collection借口. 细节见后面的列子.

package junit4;

import calc.Calculator;
import static org.junit.Assert.assertEquals;
import org.junit.Test;
import org.junit.runner.RunWith;
import org.junit.runners.Parameterized;
import org.junit.runners.Parameterized.Parameters;

import java.util.Arrays;
import java.util.Collection;

@RunWith(Parameterized.class
public class SquareTest {

    private static Calculator calculator = new Calculator();
    private int param;
    private int result;

    @Parameters
    public static Collection data() {
        return Arrays.asList(new Object[][]{
                {0, 0},
                {1, 1},
                {2, 4},
                {4, 16},        // OK : 4 = 16
                {5, 25},
                {6, 36},
                {7, 48}        // NOK : 7 = 49 not 48
        });
    }

    public SquareTest(int param, int result) {
        this.param = param;
        this.result = result;
    }

    @Test
    public void square() {
        calculator.square(param);
        assertEquals(result, calculator.getResult());
    }

}

@Suite, 用于组合多个测试.

package junit4;

import org.junit.runner.RunWith;
import org.junit.runners.Suite;

@RunWith(Suite.class)
@Suite.SuiteClasses({
        CalculatorTest.class,
        SquareTest.class
        })
public class AllCalculatorTests {
}

参考

1.
2. Get Acquainted with the New Advanced Features of JUnit 4