For `asyncExpectThrows`, instead of taking a function,
then checking if that function can be called with zero arguments,
and then immediately calling it and checking that it returns a future,
just take the future as argument.
Since synchronus errors from calling the function were not caught
anyway, doing the entire `Future` computation directly shouldn't
change behavior.
Also make `asyncExpectThrows` and `Expect.throws` return the caught error,
so that you can use normal `Expect.something` checks on it afterwards,
instead of doing that in the `check` function.
That basically makes the `check` function unnecessary (but hard to remove
with the existing test corpus using it heavily).
This makes some uses of the `asyncExpectThrows` function slightly more
complicated, those that have no other way to create a future than calling
the argument function anyway, but other uses become simpler
when they can avoid adding the function wrapper.
TEST= Refactoring. If the tests keep running, it's successful.
Change-Id: I983eb65ea4805760339073fabc27f78c57f9a471
Reviewed-on: https://dart-review.googlesource.com/c/sdk/+/226102
Reviewed-by: Bob Nystrom <rnystrom@google.com>
Commit-Queue: Lasse Nielsen <lrn@google.com>
Devon Carew