Introduce filter to allow changing the requested dates in the Site Kit integration

[leonidasmi]

Context

Summary

This PR can be summarized in the following changelog entry:

• Introduces a filter to allow changing the requested dates in the Site Kit integration. Will be used for automated testing.

Relevant technical choices:

Test instructions

Test instructions for the acceptance test before the PR gets merged

This PR can be acceptance tested by following these steps:

• Quickly double check that the data you see in the Yoast Dashboard with and without this PR are the same (make sure you test in different tabs, to avoid cache)
• Add the following filter in your site:

add_filter( 'wpseo_custom_site_kit_base_date', 'custom_site_kit_base_date', 10 );
function custom_site_kit_base_date() {
    return 'now';
}

• In a new tab, confirm you still get the same data as before.
• Add the following filter in your site:

add_filter( 'wpseo_custom_site_kit_base_date', 'custom_site_kit_base_date', 10 );
function custom_site_kit_base_date() {
    return '2025-02-28';
}

• Go to the Yoast dashboard in a new tab and check that the data have changed
• Confirm that the data you see in the dashboard agree with the data you see for those dates in the SC and A4 platforms
  • So, if you used the 2025-02-28 date in the above filter, the dates you should use are "2025-01-31" & "2025-02-27" (and "2025-01-30" & "2025-01-03", for the compare dates)
• To make sure the filter is used properly and when it doesn't, it's not used, add the following invalid date:

add_filter( 'wpseo_custom_site_kit_base_date', 'custom_site_kit_base_date', 10 );
function custom_site_kit_base_date() {
    return '2025-42-28';
}

• Go to the Yoast dashboard in a new tab and confirm that the data are the same with if you didn't use a filter

Relevant test scenarios

• Changes should be tested with the browser console open
• Changes should be tested on different posts/pages/taxonomies/custom post types/custom taxonomies
• Changes should be tested on different editors (Default Block/Gutenberg/Classic/Elementor/other)
• Changes should be tested on different browsers
• Changes should be tested on multisite

Test instructions for QA when the code is in the RC

• QA should use the same steps as above.

Impact check

This PR affects the following parts of the plugin, which may require extra testing:

• Included in the test instructions

UI changes

• This PR changes the UI in the plugin. I have added the 'UI change' label to this PR.

Other environments

• This PR also affects Shopify. I have added a changelog entry starting with [shopify-seo], added test instructions for Shopify and attached the Shopify label to this PR.

Documentation

• I have written documentation for this change. For example, comments in the Relevant technical choices, comments in the code, documentation on Confluence / shared Google Drive / Yoast developer portal, or other.

Quality assurance

• I have tested this code to the best of my abilities.
• During testing, I had activated all plugins that Yoast SEO provides integrations for.
• I have added unit tests to verify the code works as intended.
• If any part of the code is behind a feature flag, my test instructions also cover cases where the feature flag is switched off.
• I have written this PR in accordance with my team's definition of done.
• I have checked that the base branch is correctly set.

Innovation

• No innovation project is applicable for this PR.
• This PR falls under an innovation project. I have attached the innovation label.
• I have added my hours to the WBSO document.

Fixes https://github.com/Yoast/reserved-tasks/issues/524

[coveralls]

Pull Request Test Coverage Report for Build be07f70c1352befb21c5370a2015044860002d8d

Warning: This coverage report may be inaccurate.

This pull request's base commit is no longer the HEAD commit of its target branch. This means it includes changes from outside the original pull request, including, potentially, unrelated coverage changes.

• For more information on this, see Tracking coverage changes with pull request builds.
• To avoid this issue with future PRs, see these Recommended CI Configurations.
• For a quick fix, rebase this PR at GitHub. Your next report should be accurate.

Details

• 8 of 8 (100.0%) changed or added relevant lines in 1 file are covered.
• 31 unchanged lines in 1 file lost coverage.
• Overall coverage decreased (-0.4%) to 52.41%

---

Files with Coverage Reduction	New Missed Lines	%
src/dashboard/infrastructure/integrations/site-kit.php	31	50.0%

Totals
Change from base Build c122b65f10dc870041aa32063f370fb2a203577e:	-0.4%
Covered Lines:	29103
Relevant Lines:	56572

---

💛 - Coveralls

[thijsoo]

LGTM 👍