Add canary_cdash_subproject_label hook for adding cdash subproject labels

[tjfulle]

@mdmosby and @davi0011 - this is an alternative method of specifying CDash subproject labels. It adds two plugin hooks:

canary_cdash_labels_for_subproject() -> list[str]

define subproject labels for the whole project. This is analogous to CTEST_LABELS_FOR_SUBPROJECTS

canary_cdash_subproject_label(case: TestCase) -> str

(as suggested by @mdmosby) a test can define its own subproject label. If a test's subproject label is not included in the global list of subproject labels, it is added.

For Sierra to use the plugin hook, simply add the following:

@hookimpl
def canary_cdash_subproject_label(case: TestCase) -> str | None:
    if isinstance(case, SierraTestCase):
        return case.product
    return None

[mdmosby]

Does this supersede #20?

[mdmosby]

Should this return list[str] | None and be plural, i.e., ..._labels?

[tjfulle]

I had intended to return a single subproject label for each test.

[tjfulle]

but if that is not idiomatic or expected (ie, a test belongs to several subprojects) it can be changed

[davi0011]

This change seems like it would be either Subprojects enabled if your plugin declares the hooks or specifies a list of labels on the command line but no way to enable/disable from the command line. It also implies not to support Subprojects without plugin implementation which I think would be beneficial. Is there an opposition to combining a bit of both the CLI changes form #20 and this change? I think Canary should be able to generate Subproject labels from the default implementation of a Testcase or from a given build file as well.

[tjfulle]

I am not sure I follow?

[tjfulle]

@mdmosby said:

Does this supersede #20?

I'd say augments, since we may still want to adopt the idea of a test case's labels all being subprojects (per #39 (comment))

[tjfulle]

@davi0011 said in #39 (comment)

... Is there an opposition to combining a bit of both the CLI changes form #20 and this change? I think Canary should be able to generate Subproject labels from the default implementation of a Testcase or from a given build file as well.

When I think of subproject labels, I imagine a test belonging to a single subproject. If all the test keywords become CDash subproject labels, then that test would belong to many subprojects. If that is idiomatic CDash, then I like the option of a command line flag to enable that.

[davi0011]

#39 (comment)

My understanding is that CTest uses the test labels to generate the list of Subprojects labels. Hence, I think it would be fine to leave that as a default way of getting the labels with the plugin method if you wish for a more specific method.

[tjfulle]

My understanding is that you must set the variable CTEST_LABELS_FOR_SUBPROJECT to a list of labels that CTest identifies as subprojects. If a test has one of the labels in CTEST_LABELS_FOR_SUBPROJECT, it is put into the subproject.