How to get the MethodInfo of a Java 8 method reference?

In my case I was looking for a way to get rid of this in unit tests:

Point p = getAPoint();
assertEquals(p.getX(), 4, "x");
assertEquals(p.getY(), 6, "x");

As you can see someone is testing Method getAPoint and checks that the coordinates are as expected, but in the description of each assert was copied and is not in sync with what is checked. Better would be to write this only once.

From the ideas by @ddan I built a proxy solution using Mockito:

private<T> void assertPropertyEqual(final T object, final Function<T, ?> getter, final Object expected) {
    final String methodName = getMethodName(object.getClass(), getter);
    assertEquals(getter.apply(object), expected, methodName);
}

@SuppressWarnings("unchecked")
private<T> String getMethodName(final Class<?> clazz, final Function<T, ?> getter) {
    final Method[] method = new Method[1];
    getter.apply((T)Mockito.mock(clazz, Mockito.withSettings().invocationListeners(methodInvocationReport -> {
        method[0] = ((InvocationOnMock) methodInvocationReport.getInvocation()).getMethod();
    })));
    return method[0].getName();
}

No I can simply use

assertPropertyEqual(p, Point::getX, 4);
assertPropertyEqual(p, Point::getY, 6);

and the description of the assert is guaranteed to be in sync with the code.

Downside:

• Will be slightly slower than above
• Needs Mockito to work
• Hardly useful to anything but the usecase above.

However it does show a way how it could be done.

No, there is no reliable, supported way to do this. You assign a method reference to an instance of a functional interface, but that instance is cooked up by LambdaMetaFactory, and there is no way to drill into it to find the method you originally bound to.

Lambdas and method references in Java work quite differently than delegates in C#. For some interesting background, read up on invokedynamic.

Other answers and comments here show that it may currently be possible to retrieve the bound method with some additional work, but make sure you understand the caveats.