Unit Tests: switch to PHP 7.4 Production

[jeherve]

Changes proposed in this Pull Request:

• Now that PHP 7.4 has shipped, we should be able to use the final stable version in Unit Tests.

Testing instructions:

• Not much to test here, just see if the tests pass.

Proposed changelog entry for your changes:

• N/A

[jetpackbot]

	Warnings
⚠️	The Privacy section is missing for this PR. Please specify whether this PR includes any changes to data or privacy.
⚠️	pre-commit hook was skipped for one or more commits

E2E results is available here (for debugging purposes): https://jetpack-e2e-dashboard.herokuapp.com/pr-14171

This is an automated check which relies on PULL_REQUEST_TEMPLATE. We encourage you to follow that template as it helps Jetpack maintainers do their job. If you think 'Testing instructions' or 'Proposed changelog entry' are not needed for your PR - please explain why you think so. Thanks for cooperation 🤖

Generated by 🚫 dangerJS against 386fcf9

[kraftbj]

Couple of tests are failing in 7.4, but sounds like issues with the tests themselves.

There were 2 errors:

1) WP_Test_Jetpack_Photon::test_photon_cdn_in_rest_response_with_view_context

PHPUnit_Framework_Exception: Argument #2 (No Value) of PHPUnit_Framework_Assert::assertArrayHasKey() must be a array or ArrayAccess

/tmp/wordpress-master/src/wp-content/plugins/jetpack/tests/php/test_class.jetpack_photon.php:1040

2) WP_Test_Jetpack_Photon::test_photon_cdn_in_rest_response_with_edit_context

PHPUnit_Framework_Exception: Argument #2 (No Value) of PHPUnit_Framework_Assert::assertArrayHasKey() must be a array or ArrayAccess

/tmp/wordpress-master/src/wp-content/plugins/jetpack/tests/php/test_class.jetpack_photon.php:1065

[kraftbj]

I updated #13773 to give us a playground to work on this test.

[jeherve]

It turns out PHP 7.4 is not yet ready for Ubuntu Trusty (14.04) on Travis. Work is in progress here:
php-build/php-build#599

Putting this PR on hold for now.

[kraftbj]

Alternatively, we can explore not using Trusty. An initial test led to a lot more failures, so we can examine that on it's own and not within the context of this PR if php-build's work beats us to it.

[stale]

This PR has been marked as stale. This happened because:

• It has been inactive in the past 3 months.
• It hasn’t been labeled `[Pri] Blocker`, `[Pri] High`.

No further action is needed. But it's worth checking if this PR has clear testing instructions, is it up to date with master, and it is still valid. Feel free to close this issue if you think it's not valid anymore — if you do, please add a brief explanation.

[kraftbj]

Still fiddling with it. When I dump the value, it is there, but obviously is sometimes a class instead of an array. I added some json encoding/decoding to standardize everything as an array, but still instances of Core not returning what we'd expect.

This isn't an unit test failure as much as an integration test failure, but still not sure what's happening yet.