mockito 是最常用的 java mock 库， 用于模拟创建各种对象和行为。本文会介绍一下 基础库 mockitio的用法，进行一些练习。mockitio 通常不单独使用，配合 Junit一起使用。
下面列举一下用法,
模拟对象
创建mock 对象，并且可以要求，这个对象的成员方法符合我们的行为要求。
Foo foo= Mockito.mock(Foo.class);
直接返回
直接返回，我们需要的值
when thenReturn
@Test
void returnWhatIWant() {
Foo mock = Mockito.mock(Foo.class);
Mockito.when(mock.say()).thenReturn("nice to meet you");
String result = mock.say();
Assertions.assertEquals("nice to meet you", result);
}
定制方法
定制方法，改变方法的实现
when thenAnswer
@Test
void returnBaseOneParamOrSomething() {
Foo mock = Mockito.mock(Foo.class);
Mockito.when(mock.echo(anyString()))
.thenAnswer(
new Answer<String>() {
@Override
public String answer(InvocationOnMock invocationOnMock) throws Throwable {
String argument = invocationOnMock.getArgument(0, String.class);
return "hi,"+argument;
}
});
String result = mock.echo("all");
Assertions.assertEquals("hi,all", result);
}
验证方法执行次数 和 时间
@Test
void verifyMethod() {
Foo foo = Mockito.mock(Foo.class);
foo.say();
Mockito.verify(foo).say();
Mockito.verify(foo, Mockito.times(1)).say();
Mockito.verify(foo, Mockito.timeout(1000)).say();
}
模拟静态方法
改变静态方法的行为（使用 mockito-inline 作为依赖）
@Test
void mockStaticMethod() {
try (MockedStatic<Foo> fooMockedStatic = Mockito.mockStatic(Foo.class)) {
fooMockedStatic.when(() -> Foo.hold()).thenReturn("hi");
String result = Foo.hold();
Assertions.assertEquals("hi", result);
}
try(MockedStatic<Foo> fooMockedStatic = Mockito.mockStatic(Foo.class)) {
fooMockedStatic.when(()->Foo.reply(anyString())).thenAnswer(
new Answer<String>() {
@Override
public String answer(InvocationOnMock invocationOnMock) throws Throwable {
String arg = invocationOnMock.getArgument(0,String.class);
return "hi," + arg;
}
}
);
String result = Foo.reply("1024");
Assertions.assertEquals("hi,1024",result);
}
}
模拟构造函数
改名构造函数的行为，使得创建出来的都是模拟对象。
@Test
void mockConstruction() {
try (MockedConstruction<Foo> fooMockedConstruction = Mockito.mockConstruction(Foo.class)) {
Foo foo = new Foo();
foo.say();
Mockito.verify(foo).say();
}
try (MockedConstruction<Foo> fooMockedConstruction =
Mockito.mockConstruction(
Foo.class,
new MockedConstruction.MockInitializer<Foo>() {
@Override
public void prepare(Foo foo1, MockedConstruction.Context context) {
Mockito.when(foo1.say()).thenReturn("mock");
}
})) {
Foo foo3 = new Foo();
String result = foo3.say();
Mockito.verify(foo3, Mockito.times(1)).say();
Assertions.assertEquals("mock", result);
}
}
参数匹配
只对某个方法的特定参数进行模拟，其他参数不模拟
@Test
void mockSpecificArgument() {
Foo foo = Mockito.mock(Foo.class);
Mockito.when(foo.echo(eq("hello"))).thenReturn("nonono");
Assertions.assertEquals("nonono", foo.echo("hello"));
Mockito.verify(foo).echo("hello");
Assertions.assertNull(foo.echo("other"));
Mockito.verify(foo).echo("other");
}
待续
TBD
总结，上面是我常用的一些 mockito 方法。
