Add tests for Message

[donny-dont]

This adds tests for the Message class and begins the migration from unittest to test.

[donny-dont]

@nex3 the tests were straight up copied from shelf with modifications to account for any differences between http and shelf. Also added expectations for the value of Message.isEmpty which weren't present in shelf. If any aren't applicable I'll remove.

Only other question was around contentLength. So in shelf it'll automatically get set to 0 if body is null. So wondering if we need to do anything to Message.isEmpty.

[nex3]

Only other question was around contentLength. So in shelf it'll automatically get set to 0 if body is null. So wondering if we need to do anything to Message.isEmpty.

I'm not sure if I follow. If the body is null, Message.isEmpty should be true, right?

[nex3]

What's with all the formatting changes?

[donny-dont]

I can just move it all back to using "

[donny-dont]

Reverted

[donny-dont]

  /// If `true`, the stream returned by [read] won't emit any bytes.
  ///
  /// This may have false negatives, but it won't have false positives.
  bool get isEmpty => _body.contentLength == 0;

There isn't currently a check for null its just checking for length being 0.

[nex3]

There isn't currently a check for null its just checking for length being 0.

It looks like Body.contentLength is 0 when the user passes in a null body, so that should be fine.

[nex3]

It might be nice to add some newlines to make the pubspec a bit more readable.

[donny-dont]

At this point I was figuring we just fix it up when releasing 0.12.0 into the wild

[nex3]

Sure.