chore(firebaseai): setup for mock response e2e test

[cynthiajoan]

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[cynthiajoan]

/gemini review

[gemini-code-assist]

Code Review

This pull request sets up end-to-end tests for firebase_ai by parsing a suite of mock JSON responses from an external repository. The changes also improve the robustness of the response parsing logic by handling unknown enum values gracefully and making the args field in function calls optional.

The new e2e test is comprehensive and a great addition. I've suggested a couple of enhancements to make it even more robust and complete. Specifically, I recommend failing the test if a mock response file cannot be fetched, and extending the test to cover more response types from the test data repository.

[gemini-code-assist]

Silently skipping test files when they can't be fetched (e.g., due to network issues or GitHub API rate limiting) could lead to a false sense of security if tests pass. It would be better to fail the test explicitly to indicate a problem with the test setup or environment.

Suggested change

	if (response.statusCode != 200) {
	continue;
	}
	if (response.statusCode != 200) {
	fail('Failed to fetch test file $path: ${response.statusCode} ${response.reasonPhrase}');
	}