Improve test coverage (happy path, npm failure)

[mattxwang]

Which issue, if any, is this issue related to?

Closes #9.

Is there anything in the PR that needs further explanation?

Figuring out the npm failure case is a bit of a headscratcher. The only approach I could think of is making one of the install-related scripts a failure.

Resolved with @ybiquitous's suggestion below of using an invalid dependency.

---

Separately, the happy path test is a bit unorthodox in that it actually does run npm install. I think it would be better to do this with a dry run, but currently there's no way for me to pass that argument in to npm; I can implement a dry-run feature for stylelint-create after this PR.

[mattxwang]

Running into a problem with making this test work on CI (see the PR description). Any advice or help is appreciated!

[mattxwang]

Added to prevent an infinite cycle of test fixture regeneration.

[ybiquitous]

How about using invalid dependencies instead of scripts.{prepare,preinstall} hooks? For example:

{
  "dependencies": {
    "is-obj": "0.0.1"
  }
}

is-obj does NOT have a 0.0.1 version.

[mattxwang]

How about using invalid dependencies instead of scripts.{prepare,preinstall} hooks?

Ah! That's a great suggestion, thank you! Have done that exact example and the tests pass on CI. Appreciate the advice!

I'll mark this PR ready for review.

[ybiquitous]

Thanks, @mattxwang. In addition, I got an idea to refactor the cleanup code. Like this:

// integration.test.js

import * as fs from 'node:fs';
import * as path from 'node:path';
import { execFileSync } from 'node:child_process';

function backupFiles(root) {
	const pathsToBackup = [inputs.failNpmInstall, inputs.validEnv];

	for (const pathToTest of pathsToBackup) {
		fs.copyFileSync(
			path.join(root, pathToTest, 'package.json'),
			path.join(root, pathToTest, 'package.json.bak'),
		);
	}
}

function cleanupGenFiles(root) {
	const pathsToCleanup = [inputs.failNpmInstall, inputs.validEnv];

	for (const pathToTest of pathsToCleanup) {
		for (const file of ['.stylelintrc.json', 'package-lock.json', 'node_modules']) {
			fs.rmSync(path.join(root, pathToTest, file), { recursive: true, force: true });
		}

		fs.renameSync(
			path.join(root, pathToTest, 'package.json.bak'),
			path.join(root, pathToTest, 'package.json'),
		);
	}
}

describe('stylelint-create', () => {
	beforeEach((context) => {
		backupFiles(getProjectRoot(context));
	});

	afterEach((context) => {
		cleanupGenFiles(getProjectRoot(context));
	});

	// ...
});

Keys:

• Back up package.json at runtime in beforeEach()
• Clean up files via Node.js APIs instead of Shell script
  • I believe we're more familiar with JS than Shell script, and easier to find the clean-up code in the same file
• Use context in beforeEach and afterEach hooks instead of __dirname

What do you think about this suggestion?

[mattxwang]

What do you think about this suggestion?

It's wonderful - definitely agree that using JS APIs instead of the shell is a good idea, both for maintenance and reliability (shell and Windows can be annoying). A runtime backup is also nice, since we now only have one source of truth.

Tried out your code snippet, added you as a co-author; looks like it passes both locally and on CI. Thank you for the suggestion!

[ybiquitous]

Thank you. LGTM 👍🏼