PHP Research & Evidence-Based Practice 5

Question 1

Which PHP OPcache function forces the current cached version of a file to be invalidated, useful when testing if new code changes are picked up?

Accepted Answer

opcache_invalidate()

Answer

opcache_invalidate() removes a specific file from the OPcache, forcing it to be recompiled on the next request without clearing the entire cache.

Question 2

In PHP unit testing, what is a 'test double' and why is it used in evidence-based practice?

Accepted Answer

A substitute object that replaces a real dependency during testing

Answer

A test double (mock, stub, spy, or fake) replaces real dependencies so tests isolate and verify a single unit of behavior without side effects.

Question 3

Which PHP function is used to read the contents of an external URL for research data gathering, requiring allow_url_fopen to be enabled?

Accepted Answer

file_get_contents()

Answer

file_get_contents() can retrieve remote URL content when allow_url_fopen is enabled in php.ini, though cURL is preferred for complex requests.

Question 4

When analyzing PHP application logs for patterns and error rates, which log format is most machine-readable and supports structured querying?

Accepted Answer

JSON-formatted log entries

Answer

JSON-formatted logs allow log aggregators like Elasticsearch, Datadog, or Graylog to parse, index, and query individual fields programmatically.

Question 5

Which PHP class from the standard library provides an iterator for traversing directory contents, useful in scripts that research file structures?

Accepted Answer

FilesystemIterator

Answer

FilesystemIterator extends DirectoryIterator and provides a clean OOP interface for iterating directory contents with configurable flags.

PHP - PHP Programming Language Practice Test