test: add coverage for phantom-utils (getDeclaredPackages and installCmd)

[sonukapoor]

This issue is reserved for first-time contributors. If you have contributed to open source before, please leave it for someone who has not. There are other issues labelled good first issue that are not reserved.

The task

src/overrides/detectors/phantom-utils.ts has two small functions and no tests. Both are pure, so no mocking or setup is needed.

What the functions do

getDeclaredPackages(packageJson) collects every dependency name declared across dependencies, devDependencies, peerDependencies and optionalDependencies, and returns them as a Set.

installCmd(packageManager) maps a package manager to its install command: pnpm gives pnpm add, yarn gives yarn add, bun gives bun add, and anything else gives npm install.

Steps

1. Comment here saying you would like to take it, so nobody duplicates your work.
2. Fork the repo and create a branch, for example test/phantom-utils-coverage.
3. Run npm install then npm test to confirm a clean starting point.
4. Create tests/overrides/phantom-utils.test.ts. Look at any file in tests/ for the house style; the imports use a .js extension even though the files are TypeScript, which is expected.
5. Write the tests. Suggested cases:
   • collects names from all four dependency sections
   • returns an empty set for an empty package.json
   • ignores a section that is an array rather than an object
   • ignores a section that is null
   • deduplicates a package that appears in two sections
   • returns the right command for each of pnpm, yarn, bun, npm
6. Run npm test and confirm everything passes.
7. Open a pull request with Closes #NNN in the body, using this issue's number.

Tips

Prefer one behaviour per test with a name that says what the behaviour is. it("deduplicates a package declared in two sections") is better than it("works").

Ask questions here if anything is unclear. A question is not a bother, and getting stuck is normal.

[tebii]

hello! I would like on this as my first contribution.

[sonukapoor]

Welcome @tebii, it is yours. I have assigned it to you so nobody else picks it up.

No rush and no deadline. If you get stuck at any point, ask here rather than pushing through it: working out where a project keeps its tests and how it likes them written is the genuinely fiddly part of a first contribution, and the code itself is the easy bit. tests/cli/config.test.ts is a good file to read first for the house style.

One thing that trips people up: the imports use a .js extension even though the files are TypeScript. That is correct, not a typo.