Kotlin + MockIto + Android Instrumentation Test

I am trying to run an Instrumentation test (androidTest) using Mockito in Android with Kotlin.

• I’ve the core library in my dependencies. 'org.mockito:mockito-core:3.3.3'
• My project is written in Kotlin so I’ve org.mockito:mockito-inline:3.3.3 to fix the final class issue.
• As I want to run the mocks in Android, I’ve org.mockito:mockito-android:3.3.3 also in my dependencies.

but am getting below error while compiling the code

More than one file was found with OS independent path ‘mockito-extensions/org.mockito.plugins.MockMaker’

Here’s a sample test code to reproduce the issue. Run this test as an Instrumentation test. (androidTest).

MainActivityTest

import androidx.test.ext.junit.runners.AndroidJUnit4
import org.junit.Assert.assertEquals
import org.junit.Before
import org.junit.Test
import org.junit.runner.RunWith
import org.mockito.Mock
import org.mockito.Mockito.`when`
import org.mockito.MockitoAnnotations

class Calculator {
    fun add(x: Int, y: Int): Int {
        return x + y
    }
}

@RunWith(AndroidJUnit4::class)
class MainActivityTest {

    @Mock
    lateinit var calculator: Calculator

    @Before
    fun before() {
        MockitoAnnotations.initMocks(this)
    }

    @Test
    fun test() {
        `when`(calculator.add(10, 10)).thenReturn(20)
        assertEquals(calculator.add(10, 10), 20)
    }
}

app/build.gradle

plugins {
    id 'com.android.application'
    id 'kotlin-android'
    id 'kotlin-android-extensions'
}

android {
    compileSdkVersion 29

    defaultConfig {
        applicationId "com.theapache64.mockitosample"
        minSdkVersion 16
        targetSdkVersion 29
        versionCode 1
        versionName "1.0"

        testInstrumentationRunner "androidx.test.runner.AndroidJUnitRunner"
    }

    buildTypes {
        release {
            minifyEnabled false
            proguardFiles getDefaultProguardFile('proguard-android-optimize.txt'), 'proguard-rules.pro'
        }
    }
    compileOptions {
        sourceCompatibility JavaVersion.VERSION_1_8
        targetCompatibility JavaVersion.VERSION_1_8
    }
    kotlinOptions {
        jvmTarget = '1.8'
    }

    testOptions {
        unitTests.returnDefaultValues = true
    }
}

dependencies {

    implementation "org.jetbrains.kotlin:kotlin-stdlib:$kotlin_version"
    implementation 'androidx.core:core-ktx:1.2.0'
    implementation 'androidx.appcompat:appcompat:1.1.0'
    implementation 'com.google.android.material:material:1.1.0'
    implementation 'androidx.constraintlayout:constraintlayout:1.1.3'
    
    testImplementation 'junit:junit:4.13'
    androidTestImplementation 'junit:junit:4.13'
    androidTestImplementation 'androidx.test.ext:junit:1.1.1'
    androidTestImplementation 'androidx.test.espresso:espresso-core:3.2.0'
    androidTestImplementation 'org.mockito:mockito-core:3.3.3'
    androidTestImplementation 'org.mockito:mockito-android:3.3.3'
    androidTestImplementation 'org.mockito:mockito-inline:3.3.3'
}

Isn’t it possible to run Android instrumentation test using Kotlin with Mockito ?

NOTE: If you think this is a duplicate question, I’ve searched all over the internet. There are other issues with similar stack-trace, but my case is different.

Any help would be highly appreciated

[autorunman22]

This works for me androidTestImplementation 'org.mockito:mockito-core:3.3.3' androidTestImplementation 'com.linkedin.dexmaker:dexmaker-mockito-inline:2.28.0'

[plastiv]

why this is closed? exists a solution for this? or, mockito is just for unit testing without the android said of things? i think you should update the documentation specifying that.

Android ships with forked java virtual machine tailored for resource limited mobile environments. Historically, Google Android team didn’t invest much into keeping android vm on par with desktop jvm. Up until android P (api 28, 2018) android virtual machine doesn’t support inlining api. Mockito (or any other mock library) can’t rewrite finals at runtime on such androids due to lack of supported apis.

Which leads us to next cases:

• use mockito-inline with jvm tests no problem since they run on desktop vm
• use dexmaker if you run androidTest on api 28+ android devices only
• open kotlin classes at compilation time with open keyword or all-open annotation (extra plugin) for running androidTest tests on android devices with api 27 and below

Detailed comparison table for the reference: https://mockk.io/ANDROID.html