Mock static methods with Mockito - Java Unit Testing

One of the most frustrating element when I am doing the Unit tests in Java is to not be able to mock static methods.

Sure, during a long time we got PowerMock. But, since JUnit5, PowerMock wasn't compatible and we were unable to continue with it.

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But now, we have this feature included in Mockito!

Dependencies

First, you have to add the mockito-inline library. (You can use any version up to 3.4.0)

Here is an exemple with Maven

<dependency>
    <groupId>org.mockito</groupId>
    <artifactId>mockito-inline</artifactId>
    <version>3.9.0</version>
    <scope>test</scope>
</dependency>

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Writing test

To mock a static method, you have to create a mockStatic of the class with the static method, and declare the event you want to apply to your mock.

example

@Test
public void test() {

try (MockedStatic<LoggerFactory> loggerFactoryMock = Mockito.mockStatic(LoggerFactory.class)) {
            loggerFactoryMock.when(() -> LoggerFactory.getLogger(any(Class.class))).thenReturn(loggerMock);

...
            verify(loggerMock, times(1)).error("Err message test");
...
        }
    }

Then, you just have to run your tests!

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I hope it will help you!