Android 单元测试01--JUnit测试

Android studio提供了简单的测试，你可以测试JUnit(在jvm测试)或者进行仪器测试（真机或者虚拟器）,你也可以扩展你的测试能力，比如使用Mockito来测试Android的api在unit tests，或者使用Espresso 或者UI Automator模拟用户操作在仪器测试中。
本文章主要来说JUnit测试。

测试类型

Local unit tests

位于 src/test/java

运行在JVM中，测试没有依赖于Android framework

Instrumentd tests

位于 src/androidTest/java

创建一个测试

local unit test

第一步：创建
java 类

public class User {    private String userName;    private int userAge;    private User() {    }    public User(String userName, int userAge) {        this.userAge = userAge;        this.userName = userName;    }    public void setUserName(String userName) {        this.userName = userName;    }    public String getUserName() {        return userName;    }    public void setUseAge(int userAge) {        this.userAge = userAge;    }    public int getUserAge() {        return userAge;    }    @Override    public String toString() {        return "User{" +                "userName='" + userName + '\'' +                ", userAge=" + userAge +                '}';    }}

第二步，选择User ctrl+shift+t 创建test,生成目录src/test/java

public class UserTest {    private User user;    @Before    public void setUp() throws Exception {        user = new User("Rrtoyewx", 21);    }    @After    public void tearDown() throws Exception {        System.out.println(user.toString());    }    @Test    public void testSetUserName() throws Exception {        user.setUserName("xu");        assertTrue(user.getUserName().equals("xu"));    }    @Test    public void testSetUseAge() throws Exception {        user.setUseAge(17);        assertEquals(17, user.getUserAge(), 0);    }}

第三步：运行

1. @Before test之前会调用
2. @After test之后会调用
3. @Test 每个test互不干扰，即test完之后执行下一个test，执行顺序依此为before test1 after before test2 after
4. @BeforeClass:只加载一次
5. @AfterClass:只加载一次
6. Assert类提供较多验证操作，可以使用hamcrest 增加更多的验证运算符
   比如下面的三个操作是一样的

    assertTrue(user.getUserName().equals("xu"));    assertThat(user.getUserName(),is("xu"));    assertThat(user.getUserName(),equalTo("xu"));

顺便粘一张hamcrest的操作符

Mockito

@RunWith(MockitoJUnitRunner.class)

学习网站

Mockito Contents

opearator

verify :Once created, a mock will remember all interactions. Then you can selectively verify whatever interactions you are interested in.

stubbing:

when(mock.someMethod).thenReturn()

• By default, for all methods that return a value

  数据类型 返回值 collection null int/integer 0 boolean/Boolean false

• Stubbing can be overridde

• Once stubbed, the method will always return a stubbed value, regardless of how many times it is called.
• Last stubbing is more important

Argument matchers

//anyanyInt();anyBoolean();anyXxx();//custome mathcherargThat(customeMathcher);//eqeq()

• if you are using argument matchers, all arguments have to be provided by matchers.

Verifying exact number of invocations

vertify(mock,invocations)//nevernever()//atLeastatLeast()//atMostatMost()//timestimes();

-times(1) is the default;

Stubbing void methods with exceptions

doThrow(Exception e).when(mock).someMethod();when(mock).someMethod().thenThrow(Exception e);

Verification in order

//singlemock.doFirstSomeMethod();InOrder order = inOrder(mock);order.veritfy(mock).doFirstSomeMethod();//multiplemock1.doFirstSomeMethod();mock2.doSecondSomeMethod();InOrder order = inOrder(mock1,mock2);order.veritfy(mock1).doFirstSomeMethod();order.veritfy(mock2).doSecondSomeMethod();

Making sure interaction(s) never happened on mock

//times/invocationsverify(mock,never()).someMethod//never interactionsverifyZeroInteractions(mock...);

Finding redundant invocations

mock.someMethod("1");//mock.someMethod("1")mock.someMethod("2")verify(mock).someMethod("1")vertify(mock).someMethod("2")verifyNoMoreInteractions(mock);

@mock

Stubbing consecutive calls

when(mock.someMethod()).thenReturn(1,2,3,4);mock.someMethod(); // 1mock.someMethod(); // 2mock.someMethod(); // 3mock.someMethod(); // 4mock.someMethod(); // 4mock.someMethod(); // 4 

Stubbing with callbacks

public interface Answer<T> {    T answer(InvocationOnMock invocation) throws Throwable;}when(mock.someMethod()).thenAnswer(new Answner())

when do void method(),doReturn|doThrow()|doAnswer()|doNothing()|doCallRealMethod

    doXxx().when(mock).someMethod();    doReturn()  //return value;    doThrow()   //throw exception;    doAnswer()  //callBack    doNothing() //doNothing    doCallRealMethod() // mock 对应的队形mockObject.someMethod()    doXxx().doXxx().doXxx().when(mock).someMethod();

Spying on real objects

Object object = new Object();Spy spy = spy(object);spy.add()vertity(spy).add()

• spy named “partial mocking”;
• spy :can throw Exception when studding, Therefore when using spies please consider doReturn|Answer|Throw() family of methods for stubbing

Changing default return values of unstubbed invocations (1.7)

mock = mock(Object.class,Mockito.RETURNS_SMART_NULLS);mock = mock(Object.class ,new CustomerAnsewer());// Mockito.RETURNS_SMART_NULLS :If your code uses the object returned by an unstubbed call you get a NullPointerException. This implementation of Answer returns SmartNull instead of null. SmartNull gives nicer exception message than NPE because it points out the line where unstubbed method was called. // CustomerAnsewer

Capturing arguments for further assertions(1.8)

mock.someMethod(argument);vertify(mock).someMethod(argument);ArgumentCaptor<Argument> argumentCapture = ArgumentCaptor.forClass(Argument.class);vertify(mock).someMethod(argumentCapture.capture());assert();

timeout/reset

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总结

一般使用JUnit来测试一些功能性的代码，比如验证等操作，它不能使用Android Api,除非使用Mockito 来mock一些非必要在仪器上才能进行的测试。比如说sharePerference,Sqlite等一些操作。
另外功能测试尽量小，测试的功能越小，越容易定为哪儿出了问题。