Filter examples based on TestSelector

[Duhemm]

Previously, the Specs2 runner would ignore the selectors that are passed via a TaskDef.

With this patch, when a TaskDef's selectors contains only TestSelectors, then only the examples whose name match the input selectors will be executed.

[Duhemm]

In case this ends up being accepted, I've already backported this to 4.x: backport-test-selector

[etorreborre]

Hi Martin. First of all, thanks for this PR, it looks great with all the tests! However I don't get what is the use for a TestSelector with sbt on the command line. I have always selected classes with a wildcard like testOnly *MySpec* and then individual tests (or examples in BDD terms) with testOnly *MySpec* -- ex "first example". How can I create a TestSelector from sbt's command line?

[etorreborre]

Confession: I just discovered that sbt was proposing to complete the spec names for the testOnly command when pressing TAB. Better late than never :-).

[Duhemm]

Hi Eric, thanks for taking a look.

On the command line, I don't know of a way to use the selectors. The selectors are intended to be used programmatically, for instance by an IDE that would trigger the execution of a single test, or an sbt plugin that would retry failed tests.

In the examples that you showed, the syntax to execute only a single test case works only for Specs2, whereas the solution based on test selectors is framework-agnostic.

My understanding is that this is the reason why, in sbt's test API, TaskDef has a list of selectors: so that it can be used to specify which test cases to execute within a test suite. I've noticed that ScalaTest, JUnit and MUnit already support filtering test cases based on selectors (I have pull requests open for the other major test frameworks).

Please let me know if this makes the intent behind this pull request clearer.

[etorreborre]

Thanks for your explanation @Duhemm. I left another question about the code because I'm not sure about one condition.

[etorreborre]

Excellent, thanks @Duhemm. Can you please open a PR for the backport as well?
Also, how fast do you need a release for this?

[Duhemm]

Thanks, I just opened #1217.

There's no rush in releasing! Sometime before March would be great though 😄

[etorreborre]

Perfect, that will definitely be done by then :-)

[etorreborre]

This is published now as 4.20.5 for the maintenance branch and 5.5.1 for the main branch.