Anyone have suggestions on how to e2e test Vite Plugins?

[josh-hemphill]

I'm trying to test all the configurations of a plugin, but it depends on other plugins running, so I've found even trying to run all the plugins in Vitest and then manually calling the internal generation functions don't work, I'm kinda stuck, but I assume someone has to have solved this for their plugins.

[hi-ogawa]

I'm not sure what you consider as "end" in your "e2e", so it totally depends. But relatively light-weight but still realistic way to test plugin pipeline is to use Vite's programatic API, such as createServer({ plugins: [ ... ] }) + transformRequest or build({ plugins: [... ] }).

Probably you can get some idea from Vite's own tests, for example:

vite/packages/vite/src/node/ssr/__tests__/ssrLoadModule.spec.ts

Lines 255 to 294 in 07091a1

	test('plugin error', async () => {
	const server = await createServer({
	configFile: false,
	root,
	logLevel: 'error',
	plugins: [
	{
	name: 'test-plugin',
	resolveId(source) {
	if (source === 'virtual:test') {
	return '\0' + source
	}
	},
	load(id) {
	if (id === '\0virtual:test') {
	return this.error('test-error')
	}
	},
	},
	],
	})
	onTestFinished(() => server.close())
	const spy = vi
	.spyOn(server.config.logger, 'error')
	.mockImplementation(() => {})
	try {
	await server.ssrLoadModule('virtual:test')
	expect.unreachable()
	} catch {}
	expect(
	stripVTControlCharacters(spy.mock.lastCall![0])
	.split('\n')
	.slice(0, 2)
	.join('\n'),
	).toMatchInlineSnapshot(`
	"Error when evaluating SSR module virtual:test: test-error
	Plugin: test-plugin"
	`)
	})

vite/packages/vite/src/node/__tests__/build.spec.ts

Lines 784 to 807 in 07091a1

	test('default sharedConfigBuild true on build api', async () => {
	let counter = 0
	await build({
	root: resolve(__dirname, 'fixtures/emit-assets'),
	logLevel: 'warn',
	build: {
	ssr: true,
	rollupOptions: {
	input: {
	index: '/entry',
	},
	},
	},
	plugins: [
	{
	name: 'test-plugin',
	config() {
	counter++
	},
	},
	],
	})
	expect(counter).toBe(1)
	})

If this is not "e2e" enough for you, then you can always spawn the entire vite dev/build cli and run playwright test (or any browser app level testing) against the running Vite app.