Hey, can we have few more tests and edge cases? (Like punctuation and special characters?)

Blew my mind

Ayyyy lmao, cheeky solution.

Cheeky!

Some test cases are broken, for example the following ones:

[ 6, 9, 0, 4, 3, 3, 1 ] and [ 2, 7, 7, 5, 2, 3, 0 ]
Expected: 0,1,3,4,5,6,9, instead got: 0,1,2,3,4,5,6,7,9

2 and 7 are present on the second array, but not given in the expected test.

[ 6, 7, 9, 6, 5, 9 ] and [ 1, 7, 7, 0, 3, 8 ]
Expected: 0,1,3,5,6,8,9, instead got: 0,1,3,5,6,7,8,9

7 is present on both first and second array, but not given in the expected test.

[ 6, 3, 4 ] and [ 6, 1, 6 ]
Expected: 1,3,4, instead got: 1,3,4,6 

Same as above, for 6.

Seems like the Test.assertEquals treats arrays differently even if they are the same, so the default "Run tests" in there won't work properly.
For the fellows coders: just replace the test with .assertSimilar or run the tests by clicking submit.