For asynchronous tests, the contract between test file and test runner
is implicit: runners are expected to inspect the source code for
references to a global `$DONE` identifier.
Promote a more explicit contract between test file and test runner by
introducing a new frontmatter "tag", `async`. This brings asynchronous
test configuration in-line with other configuration mechanisms and also
provides a more natural means of test filtering.
The modifications to test files was made programatically using the
`grep` and `sed` utilities:
$ grep "\$DONE" test/ -r --files-with-match --null | \
xargs -0 sed -i 's/^\(flags:\s*\)\[/\1[async, /g'
$ grep "\$DONE" test/ -rl --null | \
xargs -0 grep -E '^flags:' --files-without-match --null | \
xargs -0 sed -i 's/^---\*\//flags: [async]\n---*\//'
Add tests that assert behavior when a Promise is resolved with another
Promise whose `then` method has been overridden. Because all objects
with a `then` method are treated equivalently, the presence of a
[[PromiseState]] internal slot should have no effect on program
behavior.
These tests guard against a faulty optimization originally implemented
in V8:
https://bugs.chromium.org/p/v8/issues/detail?id=3641
Remove files that tested both PerformPromiseThen and
PromiseResolveFunction in favor of new tests that test
PromiseResolveFunction more directly and completely.
The `negative` frontmatter tag expresses an expectation for the behavior
of the test file as a whole. The `assert.throws` helper function offers
more fine-grained control over expectations because it may be applied to
specific statements and expressions. This makes it preferable in cases
where it may be used (i.e. when the test body does not describe a syntax
error or early error).
Re-implement assertions for errors to use the `assert.throws` helper
function wherever possible.
Uniformly and exhaustively test the generic aspects of the static- and
instance Promise methods, including:
- function `length` properties
- function `name` properties
- method property descriptors
