Assets folder in Android Studio Unit Test

Question

I have a Gradle project with the following structure:

project/
    src/
        androidTest/
            java/
        main/
            java/
            res/
            AndroidManifest.xml
    build.gradle

Now I want to add a unit test which uses a resource (either "raw" or "asset").

I put my resource into project/androidTest/assets/test_file and access it with getContext().getResources().getAssets().open("test_file"); (in an AndroidTestCase).

However, this gives me a FileNotFoundException. How can I fix this?

Answer 1

It looks like you're trying to create an instrumented unit test, since you want to create it in the androidTest folder.

You can use one of these two lines in your test to get the context:

• Context ctx = InstrumentationRegistry.getTargetContext(); this one will give you your app's context. You can use it to grab assets that are in src/main/assets for example.

• Context ctx = InstrumentationRegistry.getContext(); this one will give you the test app's context. You can use it to grab assets that are in src/androidTest/assets

If you want to know more about assets in unit testing you can read this post. In this github file you have an example.

Answer 2

I think you use the wrong context ( the application-context and not the instrumentation context ) use:

getInstrumentation().getContext();

Or see here where I exactly do what you want to do: https://github.com/ligi/gobandroid/blob/master/android/src/androidTest/java/org/ligi/gobandroidhd/base/AssetAwareInstrumentationTestCase.java