pkg/matcher: isEmpty should fail for null or non-collections.

[DartBot]

This issue was originally filed by bl...@google.com

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As there is no isNotEmpty matcher, you are forced to use isNot(isEmpty). However, expect(null, isNot(isEmpty)) passes because isEmpty returns false for non-collections or null. So, likewise, any other non-collection object would also wrongly pass such an expect call.

My suggested solution would be for isEmpty to throw an exception for "wrong" types.

Alternatively, an isNotEmpty matcher could be added.

Thanks,
 Andreas

[lrhn]

Removed Type-Defect label.
Added Type-Enhancement, Area-Pkg, Pkg-Unittest, Triaged labels.

[kevmoo]

Added Community-Idea, Community-StarterBug labels.

[DartBot]

This comment was originally written by bl...@google.com

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I'd call this a defect because except(myCollection, isNot(isEmpty)) not failing for null references can hide nasty bugs.

[kevmoo]

Fair.

We can wrap up a new isNotEmpty up as the new feature – depending on how this lands.

This would be an easy fix in pkg/matcher. Patches welcome.

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Removed Type-Enhancement label.
Added Type-Defect label.

[kevmoo]

Removed Pkg-Unittest label.
Added Pkg-matcher label.

[kevmoo]

dart-archive/matcher@755ee44

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Added Fixed label.

[DartBot]

This issue has been moved to dart-lang/test#2340.