Add dart: prefix for unittest library

[DartBot]

<img src="https://avatars.githubusercontent.com/u/5479?v=3" align="left" width="96" height="96"hspace="10"> Issue by sethladd
Originally opened as dart-lang/sdk#3431

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The unittest library should be accessible via dart: prefix. This will be a heavily used library by external developers who are sharing code, and thus the current solution of absolute paths isn't sufficient.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/5449880?v=3" align="left" width="48" height="48"hspace="10"> Comment by iposva-google

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I suggest that this library is being added using pub instead of dart:, overall we should carefully weigh which libraries are elevated to dart: level and which are packages that we supply.

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cc @kasperl.

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<img src="https://avatars.githubusercontent.com/u/5479?v=3" align="left" width="48" height="48"hspace="10"> Comment by sethladd

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What's the bar for getting into the dart: club? I'd love to see one syntax so we don't have to weigh the pros and cons of how we import different individual libraries.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/5479?v=3" align="left" width="48" height="48"hspace="10"> Comment by sethladd

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For the record, see https://groups.google.com/a/dartlang.org/forum/#!topic/misc/X8qDr24yzXM for public discussion.

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<img src="https://avatars.githubusercontent.com/u/5479?v=3" align="left" width="48" height="48"hspace="10"> Comment by sethladd

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Related to bug 3702

[DartBot]

This comment was originally written by [email protected]

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Unit testing is really important. Since the language is changing, building anything non-trivial on top of Dart like a reusable framework requires continuous confidence that the framework is in-sync with the language, and unit tests help us figure that out. Pub is still green, and is itself changing. Forcing third-party framework vendors to use a sketchy tool to get to the the unit test library does nothing more than encourage us to move on to another language.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/5479?v=3" align="left" width="48" height="48"hspace="10"> Comment by sethladd

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The unittest library will be available via pub. The unittest library is shipping in the SDK today, under the pkgs directory. With pub, you should be able to include it with:

dependencies:
  unittest:
    sdk: unittest

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Added WontFix label.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/17034?v=3" align="left" width="48" height="48"hspace="10"> Comment by kevmoo

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Added Pkg-Unittest label.

[DartBot]

<img src="https://avatars.githubusercontent.com/u/17034?v=3" align="left" width="48" height="48"hspace="10"> Comment by kevmoo

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Removed Area-UnitTest label.
Added Area-Pkg label.