OutputCapture reset method is package-private

[vrumvrumich]

Hello, I'm currently trying to utilize OutputCapture in my unit testing to test logging level. And I face issue that I'm not able to reset OutputCapture, but according this pull request this functionality should be implemented. My spring-boot version is 2.7.4.
Probably, I can change fixture of test every time by using @TestInstance(TestInstance.Lifecycle.PER_METHOD), but I suppose that is not the best solution.
I suppose, adding any functionality to check logging level would be a very good contributing as well.

[wilkinsona]

OutputCapture is package-private. Did you mean CapturedOutput?

It looks like support for resetting the captured output was lost amid some of the changes for (#14738, #17029, etc). We can certainly consider reinstating it in some form.

Probably, I can change fixture of test every time by using @testinstance(TestInstance.Lifecycle.PER_METHOD), but I suppose that is not the best solution.

What test framework are you using? I believe JUnit (4 and 5) uses a per-method lifecycle for each test instance by default.

[vrumvrumich]

@wilkinsona Actually, I mean reset method is package-private. Yeah, you are right by default per-method lifecycle is being used, but as far as I use dependency injection for injection CapturedOutput as method parameter, so state of object is not being wiped.
Probably, we need to move this feature back to make such resetting clear. And I assume a good idea to add method to check logging level.

[vrumvrumich]

@wilkinsona Probably, this is not too much to implement. I would be grateful to contribute a little. (using this guide)

[wilkinsona]

Actually, I mean reset method is package-private. Yeah, you are right by default per-method lifecycle is being used, but as far as I use dependency injection for injection CapturedOutput as method parameter

Ok, you're using CapturedOutput. That's what I really needed to know. The reset() method only exists on OutputCapture at the moment and the whole class is package-private. Just making the method public won't help. It would needed to be added to the CapturedOutput interface as well. Technically, that's a breaking change so we'll have to consider it carefully.

I use dependency injection for injection CapturedOutput as method parameter

Due to the pushing and popping performed by OutputCaptureExtension, one test should not be able to see output that was produced by another test. It sounds like that may not be working for you so I think we need to take a step back. Can you please provide a minimal example that reproduces the problem that you're facing, clearly showing where you'd like the output to have been reset.

[vrumvrumich]

@wilkinsona Actually, I have checked this behavior and you are right one test not see logs of another one. But in method being tested I log multiple messages with different log level and it would be so helpful to have method to check message in array view not as string one.
According to this interface CapturedOutput we have methods that just return string

[wilkinsona]

Can you please expand a bit on what you mean by "array view"?

[vrumvrumich]

@wilkinsona OutputCapture has private field systemCaptures of Deque type. CapturedOutput interface have no any access method to this field. I don't want to assert string with every log line by matching it with any regex or using mockito assetrContains on string. I want check collection of elements where each of element represent one log line. Such representation will help to asset for example with Kluent

[philwebb]

systemCaptures holds a collection of SystemCapture instance, but these don't necessarily relate to lines. They are rather a block of captured bytes (which may or may not be a complete line). I think we should keep this internal to the class.

If you want to to do per line assertions you can do .spit(...) on CapturedOutput.getAll()

[wilkinsona]

If you're using Java 11 or later, java.lang.String.lines() is another option for getting each line from the captured output.