Hi all, beginner question here. Is it possible that production code method changes mock? I’ve got fo...

# mockk

[antoniomarin]

Hi all, beginner question here. Is it possible that production code method changes mock?
I’ve got following:

// PRODUCTION
class classUnderTest(
    private val preferences: Preferences
) {

    fun changePreferenceToTrue() {
        preferences.somePreference = true        
    }
}

// TEST
@Test
fun `Given preference false when changePreferenceToTrue then check is preference updated`() {
    every { preferences.somePreference } returns false

    classUnderTest.changePreferenceToTrue()
    
    // I want to assert that this Preference is true
    print(preferences.somePreference) // always returns as defined above, in this case false
}

[mansaldebor]

Hey!
Since you told the mock to always return false, that's what it'll do, so it's pointless to assert its value.
What I would do is verify that you call the setter with value true 😊

[antoniomarin]

HI @mansaldebor thanks for your response. I’m still exploring boundaries of the unit testing 😄 Any idea how to do that?

[mansaldebor]

Something like
verify { preferences.somePreference = true }

I'm not completely sure about the syntax regarding setters and mockk.

[antoniomarin]

@mansaldebor just tried it and works! Thanks a lot! I've seen verify before but haven't understood what it does until now! Thanks once again!

[mansaldebor]

You're welcome! I'm glad it worked 😊