MockK - Failed matching mocking signature for left matchers: [any(), any()]

I want to implement some UI Tests to assure that the code implemented today works for tomorrow but when trying to see if already UI tests implemented in the past works, it throws this error:

`Caused by: io.mockk.MockKException: Failed matching mocking signature for left matchers: [any(), any()]`

This happens on an `every {} return Unit` line which there's a **object file called WakeUpTimeManager**, that **calls a .set(param1, param2)** function and **inside that function there are some inline functions** which I think it could be causing the problem but I don't know. I tried searching on the internet but couldn't find a solution.

Here's the test that throws the error:
```
@Before
fun setup() {
mockkObject(WakeUpTimerManager)
every { WakeUpTimerManager.set(any(), any()) } returns Unit
}
```

Here's the function that is calling on `every` line
```
fun set(context: Context, timer: Timer) {
if (timer.atMillis < System.currentTimeMillis()) {
return
}

if (Preset.findByID(context, timer.presetID) == null) {
return
}

//This is an inline function
withGson {
PreferenceManager.getDefaultSharedPreferences(context).edit {
putString(PREF_WAKE_UP_TIMER, it.toJson(timer))
}
}

//This is an inline function
withAlarmManager(context) {
it.setAlarmClock(
AlarmManager.AlarmClockInfo(timer.atMillis, getPendingIntentForActivity(context)),
getPendingIntentForService(context, timer)
)
}
}
```

**Question:** Why does mockk throw this error? What's going on? Is there any solution for this?

try with `mockkStatic(WakeUpTimerManager::class)`. For me `mockkObject` was not working either, but `mockkStatic` did

In my case I used type cast for `any()`. I wanted to test that a method `viewModel.show(Message())` had invoked. But this method is overloaded (has signatures of different types), so I tried to cast parameter `any()` to `Message`.

// show is overloaded method
fun show(resourceId: Int) {}
fun show(text: String) {}
fun show(message: Message) {}

// But it threw the exception.
verify { viewModel.show(any() as Message) }

// This won't work because Message() object will be different
verify { viewModel.show(Message()) }


Maybe mocking for `message` will help, but not in my case.

// val message = mockk<Message>()
// every { Message() } returns message
// verify { viewModel.show(message) }

I had to add [`mockkStatic`][1], because I used an extension method. For instance, `fun ViewExtension.show()`:

mockkStatic(ViewExtension::class.java.name + "Kt") // Like "com.example...ViewExtensionKt"

Then mock a [behaviour][2]:

every { viewModel.show(Message()) } just Runs
verify { viewModel.show(any() as Message) }


[1]:

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[2]:

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In my case I was using the wrong annotation for mocking dependencies.

I was using `@MockBean` from `org.springframework.boot.test.mock.mockito.MockBean` while I should have been using `@MockkBean` from `com.ninjasquad.springmockk.MockkBean`.

Sometimes, especially with Dagger Hilt and global test modules that replace object instances with Mockk mocks, it's not entirely clear whether one works with the mock or the real object. For me it was exactly this - I had a missing dependency, so my real instance was not replaced with the mocked instance, so mockk answered with this really weird error:

```
io.mockk.MockKException: Failed matching mocking signature for

left matchers: [any()]
at io.mockk.impl.recording.SignatureMatcherDetector.detect(SignatureMatcherDetector.kt:99)
at io.mockk.impl.recording.states.RecordingState.signMatchers(RecordingState.kt:39)
at io.mockk.impl.recording.states.RecordingState.round(RecordingState.kt:31)
at io.mockk.impl.recording.CommonCallRecorder.round(CommonCallRecorder.kt:50)
at io.mockk.impl.eval.RecordedBlockEvaluator.record(RecordedBlockEvaluator.kt:63)
at io.mockk.impl.eval.VerifyBlockEvaluator.verify(VerifyBlockEvaluator.kt:30)
at io.mockk.MockKDsl.internalVerify(API.kt:119)
at io.mockk.MockKKt.verify(MockK.kt:149)
at io.mockk.MockKKt.verify$default(MockK.kt:140)
```

In my case I was mocking a Companion object method using

mockkStatic(ObjectName::class)
every { ObjectName.method() } returns blah

What did the trick was

mockkObject(ObjectName)

Source -

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