Expose OutStream rather than StdStream in Env #2463
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By making Env expose and rely on the OutStream interface it becomes possible to create mock environments for testing. For example one can implement an OutStreamStringAccumulator that accumulates output to a String that can then be checked in a unit test. Currently the 'create()' method is provided in order to build an 'artificial' environment. This simply extends this ability to support providing alternative 'out' and 'err' stream implementations.
The examples currently used StdStream, but really they only depend on the interface defined in OutStream.
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It's arguable about whether this change should go through the RFC process. I'm tempted to say it works as a "principle of least surprise bug", where you'd expect this API to expose this interface rather than the concrete type, because the intent of allowing to create artificial environments is already there. However, before I merge, I'd like to give a chance for other folks to object to that and ask this to go through RFC. I'm marking this as "needs discussion during sync" so we can plan to discuss it on Wednesday but we may resolve asynchronously ahead of time. |
jemc
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changelog - changed
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We are good to merge this AFTER 0.21.3 has been released. Temporarily marking as DO NOT MERGE. Thanks @sgebbie |
SeanTAllen
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do not merge
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That's great. Thanks for the update. |
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@sgebbie i'm doing the 0.21.3 release tomorrow. too exhausted to do it today. |
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0.21.3 has been released. merging. thanks @sgebbie. |
By making Env expose and rely on the OutStream interface it becomes
possible to create mock environments for testing. For example one can
implement an OutStreamStringAccumulator that accumulates output to a
String that can then be checked in a unit test.
Currently the 'create()' method is provided in order to build an
'artificial' environment. This simply extends this ability to support
providing alternative 'out' and 'err' stream implementations.