How to use a custom test runner in an AndroidLibraryProject

I'm trying to get code coverage into an SDK that I develop.

Thanks to:

http://ift.tt/1KKZgru

I've determined that i need to implement a custom test runner. I've got one, however since I'm buiding a library project it's unclear to me how to make this the runner used.

If I configure the instrumentation in my manifest like so:

<instrumentation
    android:name="android.test.InstrumentationTestRunner"
    android:targetPackage="com.sdk.test" />

<instrumentation
    android:name=".MyTestRunner"
    android:targetPackage="com.sdk.test" />

It doesn't work, the tests are still run by the default runners.