• Gradle scans the classes for @Test annotations and other constructs that indicate test classes. This is when the exception is thrown (see the stack trace I provided).

• It uses ASM5 to do this. This is needed because ASM4 won't understand Java8 bytecode.

• While using ASM5, it still passes Opcodes.ASM4 as API key.

• Because of telling ASM that Gradle's using the ASM4 API, ASM throws an exception when it encounters elements that weren't present in ASM4. The type annotation, introduced with Java8, is a typical example of such an element.

• ASM would simply ignore the type annotation, if the API version was set to ASM5 – which is actually the right thing to do. Type annotations can be safely ignored when scanning for test classes, but ASM want's to know that you are aware of the fact that you might encounter a type annotation (which you do with the ASM5 API key).

• Resolution: Init your ASM visitors with API version ASM5. Intentionally using ASM5 and passing ASM4 to the visitor's constructor as API version is a weird thing to do, anyway. The effect will be that the ClassVisitor will simply ignore type annotations instead of throwing an exception.

When tests contain type annotations, gradle will fail with an exception (Stack Trace). This is reproducible both with Gradle 2.2.1 and 2.3-rc-1, e.g. using a class like this:

public abstract class Dog implements Animal, @Trait Talkative {
}

Same Issue with Gradle 2.2, 2.3

Already fixed in commit 1170a186 for GRADLE-3157.

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Thanks again for reporting this issue. We haven't heard back from you after our inquiry from November 15th. We are closing this issue now. Please create an issue on GitHub if you still feel passionate about getting it resolved.