[Tests] Remove filesystem mocks in dev-override.test.ts

[gonzaloriestra]

User's Goal

The goal is to update the test suite to use real file system interactions within a temporary directory instead of mocking global file system functions, adhering to the project's testing standards.

Evaluation of the Solution

Core Functionality

The patch successfully migrates the tests from using vi.mock for @shopify/cli-kit/node/fs to using inTemporaryDirectory and writeFile. This ensures that the code under test interacts with a real (though temporary) file system, which is a more realistic and less brittle way to test file-related logic.

Safety & Side Effects

• Regressions: There are no regressions in functionality. The tests still cover the same scenarios (missing file, invalid JSON, create vs update preview, etc.).
• Over-reaching: The changes are strictly limited to the test file.
• Security: No security vulnerabilities or exposed secrets were introduced.

Completeness

The patch correctly updates all test cases within the file. It appropriately handles dynamic path generation using joinPath and updates error message assertions to include the dynamic paths where necessary.

How to test your changes?

CI

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PR created automatically by Jules for task 12302561209149859480 started by @gonzaloriestra

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