test_frame_src_csp_header_set fails on customized ALLOWED_IFRAME_SOURCES #5068

Describe the Bug

test_frame_src_csp_header_set() (in tests/SecurityHeaderTest.php) tests the CspHeader->frame-src against a fixed string, identical to the default-setting for ALLOWED_IFRAME_SOURCES.
If we customize ALLOWED_IFRAME_SOURCES in our .env, the test fails.

Comparable Environment Variables are defined in the phpunit.xml, but unfortunately not ALLOWED_IFRAME_SOURCES

I will provide a Pull-Request for phpunit.xml soon.

Steps to Reproduce

1. Add a line like ALLOWED_IFRAME_SOURCES="https://*.draw.io https://*.youtube.com https://*.youtube-nocookie.com https://*.vimeo.com https://*.google.com" to your .env-file
2. Execute vendor/bin/phpunit --filter test_frame_src_csp_header_set
3. The test fails

Failed asserting that two strings are equal.
--- Expected
+++ Actual
@@ @@
-'frame-src 'self' https://*.draw.io https://*.youtube.com https://*.youtube-nocookie.com https://*.vimeo.com'
+'frame-src 'self' https://*.draw.io https://*.youtube.com https://*.youtube-nocookie.com https://*.vimeo.com https://*.google.com'

Expected Behaviour

The test should pass.

The tests should not rely on the ALLOWED_IFRAME_SOURCES-value set in .env. Instead, phpunit.xml should define the value of this env-var.

Screenshots or Additional Context

No response

Browser Details

CLI / PHPUnit

Exact BookStack Version

v24.03-dev