How does MockitoHamcrest handle primitive boolean arguments

Why `argThat` Doesn't Work with Primitive Booleans

The `argThat` method in Mockito is designed to work with object types, not primitive types. When you try to use `argThat` with a primitive boolean, it attempts to auto-unbox the primitive to an object, which can cause issues if the primitive is not properly initialized or if it is null. This can lead to a `NullPointerException` because the matcher expects an object, not a primitive.

Using `booleanThat`

To handle primitive boolean arguments, MockitoHamcrest provides the `booleanThat` method. This method allows you to specify a Hamcrest matcher for boolean values. Here's how you can use it:

java
import org.mockito.hamcrest.MockitoHamcrest;
import org.hamcrest.Matcher;
import org.hamcrest.Matchers;

// Define a matcher for boolean values
Matcher matcher = Matchers.equalTo(true);

// Use booleanThat to match the boolean argument
MockitoHamcrest.booleanThat(matcher);

In this example, `booleanThat` is used with a matcher that checks if the boolean value is `true`. This approach ensures that you can effectively use Hamcrest matchers with primitive boolean arguments in your tests.

Example Use Case

Suppose you have a method that takes a boolean argument and you want to verify that it is called with a specific boolean value. You can use `booleanThat` in conjunction with Mockito's `verify` method to achieve this:

java
import org.mockito.Mockito;

// Mock an object
MyClass mock = mock(MyClass.class);

// Call the method on the mock object
mock.myMethod(true);

// Verify that the method was called with the correct boolean value
verify(mock).myMethod(MockitoHamcrest.booleanThat(Matchers.equalTo(true)));

In this example, `booleanThat` is used to verify that the `myMethod` was called with the boolean argument `true`.

Conclusion

MockitoHamcrest's `booleanThat` method provides a convenient way to handle primitive boolean arguments when using Hamcrest matchers in Mockito tests. It helps avoid the limitations of `argThat` with primitive types and ensures that your tests are robust and reliable.