Io.mockk.mockkexception: failed matching mocking signature for

io.mockk.MockKException: failed matching mocking signature for <signature>

The MockKException is an exception that occurs when the mocking signature provided in the mockk
library fails to match the behavior defined for the mock object. This exception is thrown when a method call on
the mock object does not match the expectations set on that object.

To understand this exception in detail, let’s consider an example.

// Given
val mockObject = mockk<SomeClass>()

// When
every { mockObject.someMethod() } returns "SomeValue"

// Then
assertThat(mockObject.someMethod()).isEqualTo("AnotherValue") // Throws MockKException

In this example, we create a mock object of type SomeClass using the mockk() function.
Next, we define the behavior of the someMethod() function using the every block and the
returns() function. Here, we expect the someMethod() function to return
"SomeValue".

Finally, we assert that the result of calling someMethod() on the mock object is equal to
"AnotherValue". Since the actual result does not match the expected value, it throws a
MockKException.

The MockKException provides detailed information about the mismatched mocking signature, allowing us
to identify where the issue lies. It helps in debugging and fixing the problem in our test code.