Ensure optimization is performed in the wp-env local environment and log debug messages to console when disabled

[westonruter]

I was testing Optimization Detective and I was confused why it wasn't working. Pages which normally had been optimized were being served as if Optimization Detective wasn't even active. It turns out that this is a side effect of #1762 where we prevent any page processing when the REST API for storing URL Metrics is unavailable. Since loopback requests don't work in wp-env (WordPress/gutenberg#20569), neither does the Site Health test for checking whether the REST API is available.

Without the patch in this PR, a plugin can force optimization to apply even when the REST API isn't available via code like the following:

// The wp-env environment does not support loopback requests, so we need to pretend that everything is good.
add_filter(
	'pre_option_od_rest_api_unavailable',
	static function ( $pre ): string {
		if ( ! is_admin() ) {
			return '0';
		}
		return $pre;
	}
);

This could be added to the od-dev-mode plugin. But this plugin shouldn't have to be installed in order to test Optimization Detective in wp-env.

So this PR adds a condition (a7cedce) so that od_is_rest_api_unavailable() is checked alongside ( wp_get_environment_type() !== 'local' || class_exists( 'Test_OD_Optimization' ) ). Only if both are true will it short-circuit.

Additionally, to assist with helping users understand why Optimization Detective isn't doing anything, this PR includes the reasons for optimization being disabled in the console when WP_DEBUG is enabled.

[github-actions]

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Co-authored-by: westonruter <[email protected]>
Co-authored-by: felixarntz <[email protected]>

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[westonruter]

I wish the class_exists( 'Test_OD_Optimization' ) check weren't needed, but there's apparently no way to override the return value of wp_get_environment_type() in tests.

[felixarntz]

Not a blocker, but is there a more generic way to check if tests are being run? Maybe a constant that the WP core unit test suite always sets?

[westonruter]

Test coverage for this condition can't be added due to #1271.

[codecov]

Codecov Report

Attention: Patch coverage is 82.35294% with 6 lines in your changes missing coverage. Please review.

Project coverage is 65.96%. Comparing base (b7c4475) to head (e6135b8).
Report is 29 commits behind head on trunk.

Files with missing lines	Patch %	Lines
plugins/optimization-detective/optimization.php	82.35%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##            trunk    #1822      +/-   ##
==========================================
+ Coverage   65.47%   65.96%   +0.49%     
==========================================
  Files          85       88       +3     
  Lines        6748     6876     +128     
==========================================
+ Hits         4418     4536     +118     
- Misses       2330     2340      +10     

Flag	Coverage Δ
multisite	65.96% <82.35%> (+0.49%)	⬆️
single	38.64% <82.35%> (+0.76%)	⬆️

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[felixarntz]

@westonruter LGTM, just two minor notes.

[felixarntz]

Not a blocker, but is there a more generic way to check if tests are being run? Maybe a constant that the WP core unit test suite always sets?