Jacoco coverage for switch statement

Question

I am working to get 100% code coverage for a library I am working on and I seem to have some issues with a switch statement and the coverage which I simply don't understand.

I am currently using Jacoco 0.7.2 because every newer version seems to break with Robolectrics.

I test a simple switch statement:

public enum Type {
    NONE, LEGACY, AKS
}

private static Class<?> getCipherClass(Type type) {
    switch (type) {
        case LEGACY:
            return CipherWrapperLegacy.class;
        case AKS:
            return CipherWrapperAks.class;
        default:
            return null;
    }
}

The test I wrote contains the following checks (I have to use reflection as the method is private):

final CipherWrapper instance = CipherWrapper.createInstance(mockContext, CipherWrapper.Type.LEGACY, ALIAS);
assertNotNull(instance);

Method getCipherMethod = TestUtils.makeMethodAccessible(CipherWrapper.class, "getCipherClass", CipherWrapper.Type.class);
assertNull(getCipherMethod.invoke(instance, CipherWrapper.Type.NONE));
assertEquals(CipherWrapperAks.class, getCipherMethod.invoke(instance, CipherWrapper.Type.AKS));
assertEquals(CipherWrapperLegacy.class, getCipherMethod.invoke(instance, CipherWrapper.Type.LEGACY));

The result is not what I have expected:

The image is a bit confusing as the yellow line suggests that there is something missing. The green icon tells me that 3 of 3 branches are covered.

I also tested to extend the switch case with case NONE and a fall through but it didn't change anything.

The only thing I can do is to replace the switch with if/else and then I get 100% coverage.

Currently I have 98% coverage but I nothing is missed based on the overview:

Answer 1

If the invoke method doesn't like you putting in an anonymous variable:

getCipherMethod.invoke(instance, (CipherWrapper.Type) null);

Then try it with a named variable:

CipherWrapper.Type nullType = null;
getCipherMethod.invoke(instance, nullType);

Also, you should check if the invocation exception is just wrapping an exception caused by invoking the method rather than an error with invocation itself.