[rhcos-4.17] - Backport failing test for FIPS & LUKS

[aaradhak]

Backporting #4181

[gemini-code-assist]

Code Review

This pull request adds a new test to verify that cryptsetup lukscreate fails with FIPS-incompatible algorithms. The overall logic of the test is sound. I've made a couple of suggestions to improve code quality and robustness: one related to error handling to preserve stack traces for better debugging, and another to simplify a helper function and make it more robust against invalid inputs.

[gemini-code-assist]

Calling err.Error() can discard useful information, such as a stack trace if the error was created with pkg/errors. It's better to pass the error object directly to c.Fatal() for better debugging.

Suggested change

	if err := ignitionFailure(c); err != nil {
	c.Fatal(err.Error())
	}
	if err := ignitionFailure(c); err != nil {
	c.Fatal(err)
	}

[gemini-code-assist]

This function can be simplified. The comments are noisy and partially incorrect. Using regexp.MustCompile on a pattern passed as an argument is risky as it will panic on an invalid pattern. A better approach is to use a function like regexp.Match which returns an error on compilation failure, making the function more robust.

// fileContainsPattern reads a file and reports whether it contains a match for a regular expression.
func fileContainsPattern(path string, searchPattern string) (bool, error) {
	file, err := os.ReadFile(path)
	if err != nil {
		return false, err
	}
	return regexp.Match(searchPattern, file)
}