True, but an array can be initialized with null, then you will get NullPointerException:

String[] test = null;

and considering there was a test

@Test
public void validateNull() {
	assertNull(SmashWords.smash(null));
}

i'd go for a null check before returning.

One of the assumptions in the details was the you were given an array.

That error IS strange. Unfortunately I have no idea what to debug. Can you please share your code? You can mark it as a spoiler and it should stay hidden.

Thank you! I'll stick toLowerCamelCaseFromNowOn ;)

@liry

Thanks for feedback!
What is the current standard in Java to start member names? Or there is none? (Please do not direct me to stack-overflow-like-pages because the answers there are very inconsistent ;) )
All info appreciated.

I am a C# developer trying out Java and ... old habits die hard ;)

You're right. I forgot to pass the initial 0 to inject. Should have been:
def squareSum(numbers)
numbers.inject(0) { |sum,x| sum + x**2 }
end