Add tests for when-let

[alysbrooks]

Tests are based on the tests for when-first.

[alysbrooks]

when-let only accepts a single pair of bindings so it occurs to me that we could check that additional pairs aren't accepted by checking doing so it throws an exception.

This is how when-let does it in Clojure itself:

(assert-args
    (vector? bindings) "a vector for its binding"
    (= 2 (count bindings)) "exactly 2 forms in binding vector")

[jeaye]

when-let only accepts a single pair of bindings so it occurs to me that we could check that additional pairs aren't accepted by checking doing so it throws an exception.

Yeah, I think this makes sense. It is on the macro to validate its own inputs, so we can test that logic.

[alysbrooks]

It turned out clunkier than I expected, as the exception is thrown during compilation and can't be caught. I also couldn't test for a very specific exception, as I think that could vary by implementation.

[alysbrooks]

Hmm, looks like that doesn't work for ClojureScript.

[jeaye]

CLJS does weird stuff with macros. We could just disable that test for CLJS using a reader conditional.

[E-A-Griffin]

Yeah I'd second the suggestion to just not test cljs for that case, there's still value for the other dialects