_.union should produce correct result when passed a falsey array argument.

[jdalton]

_.union(null, [1,2,3]);

// => [null, 1, 2, 3]
// instead of
// => [1, 2, 3]

This can happen if you pass somthing like _.union(someString.match(...), others);.

[jashkenas]

It's undefined behavior, but sure. I'm not seeing this problem.

[jdalton]

You're testing for the wrong result.
The correct result, and the result in v1.4.4, is [1, 2, 3] not [null, 1, 2, 3].

[jashkenas]

_.union([null, 1, 2, 3])
[null, 1, 2, 3]

... how exactly is that the wrong result?

[jdalton]

The test should be for _.union(null, [1, 2, 3]) not _.union([null, 1, 2, 3]).
In v1.4.4 _.union(null, [1, 2, 3]) returned [1, 2, 3] which is correct, but in v1.5 it returns [null, 1, 2, 3] which is not.

[ghost]

Ping. You still have not corrected your invalid test here.