执行Espresso测试时遇Multiple dex files define错误求解决方案

Hey there, let's tackle that frustrating "multiple dex files define" error you're facing when running Espresso tests. The root cause here is a version conflict between the support libraries used by your app and the older Espresso version you're relying on.

Why This Happens #

Your app uses com.android.support:appcompat-v7:27.0.0, but Espresso 2.2.2 depends on much older support library versions (around 25.x). When Gradle resolves dependencies, it ends up pulling two different versions of the same support classes, leading to the duplicate dex file error. Even though you excluded support-annotations from Espresso, there are other implicit support library dependencies causing the conflict.

Solution 1: Upgrade Espresso to Match Your Compile SDK (Recommended) #

Since your compileSdkVersion is 27, you should use an Espresso version compatible with support library 27. The correct version here is Espresso 3.0.1. Update your dependencies like this (note we're using modern Gradle configurations instead of deprecated compile/androidTestCompile):

dependencies {
    implementation fileTree(dir: 'libs', include: ['*.jar'])
    androidTestImplementation 'com.android.support.test.espresso:espresso-core:3.0.1'
    implementation 'com.android.support:appcompat-v7:27.0.0'
    implementation 'com.android.support.constraint:constraint-layout:1.0.2'
    testImplementation 'junit:junit:4.12'
}

• Upgrading Espresso ensures full compatibility with your 27.x support libraries, eliminating the duplicate dex files issue entirely.
• Using implementation and androidTestImplementation is the recommended approach for newer Gradle versions (they replace the outdated compile/testCompile keywords).

Solution 2: Force All Dependencies to Use Your Support Library Version #

If you can't upgrade Espresso for some reason, you can force Gradle to use your 27.0.0 support library versions across all dependencies. Add this block inside your android section in build.gradle:

android {
    compileSdkVersion 27
    buildToolsVersion "27.0.3"
    defaultConfig {
        // ... your existing defaultConfig settings
    }
    buildTypes {
        // ... your existing buildTypes settings
    }

    // Force uniform support library versions
    configurations.all {
        resolutionStrategy.force 'com.android.support:support-annotations:27.0.0'
        resolutionStrategy.force 'com.android.support:support-v4:27.0.0'
        resolutionStrategy.force 'com.android.support:support-core-utils:27.0.0'
        // Add other support libraries if you spot conflicts in the dependency tree
    }
}

This tells Gradle to ignore any older support library versions pulled in by Espresso (or other dependencies) and use your 27.0.0 versions instead.

Verify Dependencies (Optional) #

To check for other potential conflicts, run this command in your project root to view the full dependency tree:

./gradlew app:dependencies

Look for duplicate entries under com.android.support to identify any other conflicting libraries.

内容的提问来源于stack exchange，提问作者shivam