java Mockito - 当然后返回
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Mockito - when thenReturn
提问by Paz
I'm new to the Mockito library and I can't understand the following syntax: before the test I defined -
我是 Mockito 库的新手，无法理解以下语法：在我定义的测试之前 -
when(CLASS.FUNCTION(PARAMETERS)).thenReturn(RETURN_VALUE)
And the actual test is -
实际测试是——
assertSame(RETURN_VALUE, CLASS.FUNCTION(PARAMETERS))
Don't I just set the return value of the function with the first line of code (when... thenReturn) to be RETURN_VALUE? If the answer is yes, then of course assertSamewill be true and the test will pass, what am I missing here?
我不是只是将第一行代码 ( when... thenReturn)的函数的返回值设置为RETURN_VALUE？如果答案是肯定的，那么当然assertSame会是真的并且测试会通过，我在这里错过了什么？
回答by Mureinik
The point of Mockito (or any form of mocking, actually) isn't to mock the code you're checking, but to replace external dependencies with mocked code.
Mockito（或任何形式的模拟，实际上）的重点不是模拟您正在检查的代码，而是用模拟代码替换外部依赖项。
E.g., consider you have this trivial interface:
例如，假设您有这个简单的界面：
public interface ValueGenerator {
int getValue();
}
And this is your code that uses it:
这是您使用它的代码：
public class Incrementor {
public int increment(ValueGenerator vg) {
return vg.getValue() + 1;
}
}
You want to test your Incrementorlogic without depending on any sepecific implementation of ValueGenerator.
That's where Mockito comes into play:
您想在Incrementor不依赖于ValueGenerator. 这就是 Mockito 发挥作用的地方：
// Mock the dependencies:
ValueGenerator vgMock = Mockito.mock(ValueGenerator.class);
when(vgMock.getValue()).thenReturn(7);
// Test your code:
Incrementor inc = new Incrementor();
assertEquals(8, inc.increment(vgMock));
