kotlin.Result<T> mocking is not working as expected

Prerequisites

Please answer the following questions for yourself before submitting an issue.

• I am running the latest version (checked on 1.10.6 and 1.11.0)
• I checked the documentation and found no answer
• I checked to make sure that this issue has not already been filed

Expected Behavior

I expect that mockk treats kotlin.Result<T> class as other classes

Current Behavior

It seems that it is unnecessary wrapping any Result<T> return type to another Result.success instance making even a basic test fail.

Failure Information (for bugs)

I have no useful information at this time… I’ll add if I find useful info.

Steps to Reproduce

Let’s consider this piece of code:

    class Data

    interface MyInterface {
        fun getData(): Result<Data>
    }

Now I’m gonna test, with a mockk of MyInterface, that it returns the instance of Data class wrapped in a Result.success instance:

    @Test
    fun testWithBug() {
        val myDataResult = Result.success(Data())
        val myInterface = mockk<MyInterface> {
            every { getData() } returns myDataResult
        }

        assertSame(myDataResult, myInterface.getData())
    }

This test fails with:

java.lang.AssertionError: expected same:<Success(com.my.test.MyTest$Data@6e0cff20)> was not:<Success(Success(com.my.test.MyTest$Data@6e0cff20))>
Expected :Success(com.my.test.MyTest$Data@6e0cff20)
Actual   :Success(Success(com.my.test.MyTest$Data@6e0cff20))

But there’s no code wrapping the Data() in two successes… from where does it come?

The thing is that it’s a problem of the Result class because if you do this, the test passes:

    class Data

    interface MyInterface {
        fun getData(): Data
    }

    @Test
    fun testWithBug() {
        val myDataResult = Data()
        val myInterface = mockk<MyInterface> {
            every { getData() } returns myDataResult
        }

        assertSame(myDataResult, myInterface.getData())
    }

Context

Please provide any relevant information about your setup. This is important in case the issue is not reproducible except for under certain conditions.

• MockK version: 1.10.6 and 1.11.0
• OS: macOS 10.15.7
• Kotlin version: 1.5.10
• JDK version: 1.8.0_282
• JUnit version: 4.13.2
• Type of test: unit test

Minimal reproducible code (the gist of this issue)

// -----------------------[ GRADLE DEFINITIONS ] -----------------------
dependencies {
    testImplementation "junit:junit:4.13.2"
    testImplementation "io.mockk:mockk:1.11.0"
}
// -----------------------[ YOUR CODE STARTS HERE ] -----------------------
package com.my.test

import io.mockk.every
import io.mockk.mockk
import org.junit.Assert.assertSame
import org.junit.Test

class MyTest {
    class Data

    interface MyInterface {
        fun getData(): Result<Data>
    }

    @Test
    fun testWithBug() {
        val myDataResult = Result.success(Data())
        val myInterface = mockk<MyInterface> {
            every { getData() } returns myDataResult
        }

        assertSame(myDataResult, myInterface.getData())
    }
}
// -----------------------[ YOUR CODE ENDS HERE ] -----------------------

[siboxd]

Any news on this? Could you put the important label?

[deadeyye]

This is known problem, it should be solved by this https://github.com/mockk/mockk/pull/633 Now we just need to wait for release.