Rewrite isEmpty and isNotEmpty to just access the isEmpty/isNotEmpty.

Adapt the unit tests and add a small regression test for
https://code.google.com/p/dart/issues/detail?id=21562 to check that
`expect(null, isNot(isEmpty))` fails.

BUG=21792, 21562
4 files changed
tree: 3edc9db989798f6047fad175aba9b8fb85650cb0
  1. .gitignore
  2. .status
  3. CHANGELOG.md
  4. LICENSE
  5. README.md
  6. codereview.settings
  7. lib/
  8. pubspec.yaml
  9. test/
README.md

Support for specifying test expectations, such as for unit tests.

The matcher library provides a third-generation assertion mechanism, drawing inspiration from Hamcrest.

For more information, see Unit Testing with Dart.