Getting code coverage from phpunit?

[mmarco9]

I would like to obtain test coverage by using phpunit. I am passing the parameter --coverage-text=cov.txt, however the output tells me of 0% code coverage. I am wondering if I am doing something wrong, or if it's not possible to obtain code coverage on these tests.
I appreciate any help!

[jrf]

Loosely related to #46373

[jrf]

@mmarco9 I've looked into this and you are completely right.

The standard phpunit.xml.dist and tests/phpunit/multisite.xml files, both set the WP_RUN_CORE_TESTS constant.

With the WP_RUN_CORE_TESTS constant in place, the source code used for the unit tests is in the build directory created by running npm run build, not in the src directory.

This is loosely related to the changes made in #43055.

I'm attaching two patches to this ticket:

Patch 1

A patch fixing code coverage setup in the phpunit.xml.dist file to point to the build directory which makes the config consistent with the WP_RUN_CORE_TESTS being set to 1 in the same config file.

This patch included updating the list, as added in #43067 / #43240 / [42665], to be in line with the current code base and excluding the plugins and themes included with WP Core from being considered for code-coverage.

If people locally have a phpunit.xml file which changes the WP_RUN_CORE_TESTS constant to 0, they would also - in their local file - have to change the code coverage setup to use the src directory.

Patch 2

A patch to fix a number of malformed @covers tags. These will throw warnings in higher PHPUnit versions and will at some point no longer record the coverage properly (I haven't dug in for the exact PHPUnit version numbers).

As per the ​documentation of the `@covers` tag, global functions being covered should be prefixed with ::. Also, the () behind the function name is redundant.

This patch is a follow-up on #39235.

I'd also recommend for tests covering classes to be explicit about the fact that these are global classes by adding a \ at the start, i.e. @covers \SomeClass, not @covers SomeClass, but that is not included in the current patch.

@SergeyBiryukov These are the two patches I mentioned yesterday.

[jrf]

Fix the code coverage configuration in phpunit.xml.dist

[jrf]

Fix invalid code coverage tags

[SergeyBiryukov]

In 48847:

Build/Test Tools: Update code coverage setup in the phpunit.xml.dist file to point to the build directory.

This makes the configuration consistent with the WP_RUN_CORE_TESTS constant being set to 1 in the same config file.

Additionally, update the list to be in line with the current codebase, excluding the plugins and themes bundled with WordPress core from being considered for code coverage.

Note: If you have a local phpunit.xml file that changes the WP_RUN_CORE_TESTS constant to 0, you should also - in the same file - change the code coverage setup to use the src directory.

Follow-up to [42665], [43311].

Props jrf, mmarco9.
See #50267.

[SergeyBiryukov]

In 48848:

Tests: Correct a number of malformed @covers tags.

As per the documentation of the @covers tag, global functions being covered should be prefixed with ::. Also, the () after the function name is redundant.

Follow-up to [39918].

Props jrf.
See #50267.

[SergeyBiryukov]

Marking as needs-dev-note to mention the note in [48847].

[daisyo]

Dev note published: ​https://make.wordpress.org/core/2020/11/20/miscellaneous-developer-focused-changes-in-wordpress-5-6/