Remove private function tests from params_test.go

[Copilot]

The params_test.go file contained tests for the mask() function, which is a private function defined in refrax_client.go. Private functions should not be tested separately, and these tests were unrelated to the params package.

Changes:

• Removed 7 TestMask_* test functions from internal/client/params_test.go
• Retained all TestNewMockParams_* tests which properly test the public API of params.go

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[Copilot]

Pull request overview

This PR improves test organization by removing misplaced tests for a private function. The params_test.go file previously contained 7 test functions (TestMask_*) that were testing the private mask() function from refrax_client.go, which was inappropriate since test files should only test the public API of their corresponding source file.

Key changes:

• Removed 7 test functions (TestMask_ReturnsEmptyForEmptyToken through TestMask_ShowsThreeCharacters) that tested the private mask() function
• Retained all 14 TestNewMockParams_* tests that properly test the public NewMockParams() function from params.go

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[Copilot]

While removing tests for the private mask() function from this file is correct (as it doesn't belong in params_test.go), the mask() function in refrax_client.go is now completely untested. The mask() function is used for security purposes to mask sensitive tokens in debug logs (line 328 of refrax_client.go). Consider adding tests for this function in refrax_client_test.go to ensure it properly masks tokens of various lengths, especially since it handles a security-sensitive operation.