Bump to core-3.0.0, move to vitest, support ESM modules

[ncipollo]

Note

Medium Risk
Moderate risk because it changes the module system to ESM and updates GitHub Actions dependencies/test tooling, which can affect runtime imports and CI behavior despite minimal functional logic changes.

Overview
Moves the project to ESM and Vitest-based testing. Tests are migrated from Jest to vitest, including new __mocks__ for @actions/core and fs, updated mocking patterns, and updated imports to use explicit .js extensions.

Updates tooling/config. Enables Biome v2 linting/organize-imports configuration, adds a vitest.config.ts with coverage thresholds, bumps @actions/core to ^3.0.0, and expands .gitignore for Copilot/Claude local settings.

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[cursor]

Unused writeFileSync mock export

Low Severity

writeFileSync is exported as a mock function but is never used in any source or test file in the codebase. This is dead code that should be removed.

 

[cursor]

Cursor Bugbot has reviewed your changes and found 2 potential issues.

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[cursor]

Unused constant _generateReleaseNotes is dead code

Low Severity

The constant _generateReleaseNotes is declared but never used anywhere in the file. The createAction function uses a literal default value generateReleaseNotes = true directly in its parameter list, making this constant unnecessary dead code.

 

[cursor]

Unused mock variable _mockStatSync is dead code

Low Severity

The variable _mockStatSync is created via vi.mocked(fs.statSync) but is never used in any test. Unlike mockReadFileSync and mockExistsSync which are used for setting up mock behaviors, this mock wrapper serves no purpose in the tests.