Run instrumented test inside module's androidTest

Question

Is it possible to run an instrumented test in an Android module that has no activity but uses AppCompat dependencies? I am attempting to run a simple test but only works if moved to app module.

Util class to test

/**
 * Typical email validation
 * */
fun validateEmail(email: String?): ValidationResult {
    val emailInput: String? = email?.trim()
    return when {
        (emailInput.isNullOrBlank()) -> {
            ValidationResult(
                isSuccessful = false,
                errorMessageResource = R.string.field_required
            )
        }
        (Patterns.EMAIL_ADDRESS.matcher(emailInput).matches().not()) -> {
            ValidationResult(
                isSuccessful = false,
                errorMessageResource = R.string.invalid_email
            )
        }
        else -> {
            ValidationResult(
                isSuccessful = true
            )
        }
    }
}

Test script

@RunWith(AndroidJUnit4::class)
class ValidationUtilsTest {

   @Test
   fun invalidEmails_returnsFalse() {

     val invalidEmailList = listOf(
        "plainaddress",
        "#@%^%#$@#$@#.com",
        "@example.com",
        "Joe Smith <[email protected]>",
        "email.example.com",
        "email@[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "あいうえお@example.com",
        "[email protected] (Joe Smith)",
        "email@example",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]",
        "[email protected]"
    )

    val listResult = mutableListOf<Boolean>()

    for (invalidEmail in invalidEmailList) {
        val result = ValidationUtils.validateEmail(invalidEmail)
        listResult.add(result.isSuccessful)
    }

    assertThat(listResult.any { true }).isFalse()

  }

}

Getting these error:

java.lang.RuntimeException: Unable to instantiate instrumentation ComponentInfo

Caused by: java.lang.ClassNotFoundException: Didn't find class "androidx.test.runner.AndroidJUnitRunner" on path: DexPathList

Structure

 - app
   - libs
     - androidTest
     - test

Answer 1

Finally found the problem, I need to add the runner dependency androidx.test:runner.