Closes #6833: Refactor to comply with phpstan level 4

[Miraeld]

Description

This PR cover the level 4 of PHPStan. As I've put everything in a single commit, this could look overwhelming. However, here is a quick overview of errors PHPStan was giving:

1. Unused Methods/Properties

These errors highlight methods or properties defined in tests but never used. They might indicate dead code or functionality that was added but not utilized, possibly leftovers from refactoring or incomplete test cases.

2. Unreachable Code

PHPStan detects sections of code that can never be executed due to conditions or logic that always result in termination (e.g., return statements or exceptions). These often point to redundant code or improper flow control.

3. Boolean Logic Issues

Certain boolean expressions are flagged because they always resolve to the same outcome. This suggests logic errors, often due to overly simplistic conditions or unnecessary negations that don’t change the result.

4. Assertions that Always Evaluate to True/False

Some test assertions will always pass or fail because their conditions are inherently true or false. This reduces the usefulness of the test, indicating they need refinement or their logic adjusted for meaningful validation.

5. PHPDoc-Related Type Mismatches

PHPStan finds discrepancies between types declared in PHPDoc comments and the actual types used in the code, particularly in method calls. This could mean incorrect assumptions in documentation, which may lead to confusion or improper type handling during execution.

Fixes #6833
It doesn't impact user.

Type of change

• New feature (non-breaking change which adds functionality).
• Bug fix (non-breaking change which fixes an issue).
• Enhancement (non-breaking change which improves an existing functionality).
• Breaking change (fix or feature that would cause existing functionality to not work as before).
• Sub-task of #(issue number)
• Release

Detailed scenario

No scenario.

Technical description

Documentation

1. Unused Methods/Properties

Methods & Properties that were never used have been deleted if it was okay in the process of WP Rocket.

2. Unreachable Code

Some code were unreachable due to two main reason:
a. Some functions are stopping the execution of PHP ($this->markTestSkipped(), wp_error_json()), and we had code afterwards. In this case, as it's breaking tests if we are removing the code, a ignore line has been added.

b. Sometimes, we are returning a value, while having other function call after. In this case, this code has been removed.

3. Boolean Logic Issues

Most of the time, this is due to over-safeguarding. To avoid that, I've added typed parameters in functions and also replaced the use of apply_filters by wpm_apply_filters_typed().

4. Assertions that Always Evaluate to True/False
This happens in tests, where we have $this->assertTrue(true);. In this case a ignore line has been added to avoid the test to be flag without assertion.

5. PHPDoc-Related Type Mismatches

PhpDocumentation has been updated to reflect the truth about some function return type, and parameters as it's been modified overtime, without a change in the phpdoc, misleading PHPStan.

New dependencies

N/A

Risks

N/A

Mandatory Checklist

Code validation

• I validated all the Acceptance Criteria. If possible, provide screenshots or videos.
• I triggered all changed lines of code at least once without new errors/warnings/notices.

Code style

• I wrote a self-explanatory code about what it does.
• I protected entry points against unexpected inputs.
• I did not introduce unnecessary complexity.
• Output messages (errors, notices, logs) are explicit enough for users to understand the issue and are actionnable.

Additional Checks

• In the case of complex code, I wrote comments to explain it.
• When possible, I prepared ways to observe the implemented system (logs, data, etc.).
• I added error handling logic when using functions that could throw errors (HTTP/API request, filesystem, etc.)

[codacy-production]

Coverage summary from Codacy

See diff coverage on Codacy

Coverage variation	Diff coverage
Report missing for de60b471	✅ 69.14% (target: 50.00%)

Coverage variation details

	Coverable lines	Covered lines	Coverage
Common ancestor commit (de60b47)	Report Missing	Report Missing	Report Missing
Head commit (8028445)	37719	16561	43.91%

Coverage variation is the difference between the coverage for the head and common ancestor commits of the pull request branch: <coverage of head commit> - <coverage of common ancestor commit>

Diff coverage details

	Coverable lines	Covered lines	Diff coverage
Pull request (#6971)	81	56	69.14%

Diff coverage is the percentage of lines that are covered by tests out of the coverable lines that the pull request added or modified: <covered lines added or modified>/<coverable lines added or modified> * 100%

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_{Codacy stopped sending the deprecated coverage status on June 5th, 2024. Learn more}

Footnotes

1. Codacy didn't receive coverage data for the commit, or there was an error processing the received data. Check your integration for errors and validate that your coverage setup is correct. ↩

[Mai-Saad]

Related test plan https://wpmediaqa.testrail.io/index.php?/runs/view/899&group_by=cases:section_id&group_order=asc

[hanna-meda]

Relating Tests results below:
Uploading testrail-report-639.pdf…