Ensure `appEntrypoint` is referenced in Vue components (#9490)

* fix(#6827): ensure `appEntrypoint` is referenced in Vue components

* chore: add test

* chore: add changeset

* fix: windows handling

* Update packages/integrations/vue/src/index.ts

Co-authored-by: Bjorn Lu <bjornlu.dev@gmail.com>

* chore: address review feedback

* chore: update lockfile

---------

Co-authored-by: Bjorn Lu <bjornlu.dev@gmail.com>

1 files changed, 67 insertions, 0 deletions

diff --git a/packages/integrations/vue/test/app-entrypoint-css.test.js b/packages/integrations/vue/test/app-entrypoint-css.test.js
new file mode 100644
index 000000000..b629f1d25
--- /dev/null
+++ b/packages/integrations/vue/test/app-entrypoint-css.test.js
@@ -0,0 +1,67 @@
+import { loadFixture } from './test-utils.js';
+import { expect } from 'chai';
+import { load as cheerioLoad } from 'cheerio';
+
+describe('App Entrypoint CSS', () => {
+	/** @type {import('./test-utils').Fixture} */
+	let fixture;
+
+	before(async () => {
+		fixture = await loadFixture({
+			root: './fixtures/app-entrypoint-css/',
+		});
+	})
+
+	describe('build', () => {
+		before(async () => {
+			await fixture.build();
+		})
+
+		it('injects styles referenced in appEntrypoint', async () => {
+			const html = await fixture.readFile('/index.html');
+			const $ = cheerioLoad(html);
+
+			// test 1: basic component renders
+			expect($('#foo > #bar').text()).to.eq('works');
+
+			// test 2: injects the global style on the page
+			expect($('style').first().text().trim()).to.eq(':root{background-color:red}');
+		});
+
+		it('does not inject styles to pages without a Vue component', async () => {
+			const html = await fixture.readFile('/unrelated/index.html');
+			const $ = cheerioLoad(html);
+
+			expect($('style').length).to.eq(0);
+			expect($('link[rel="stylesheet"]').length).to.eq(0);
+		});
+	})
+
+	describe('dev', () => {
+		let devServer;
+		before(async () => {
+			devServer = await fixture.startDevServer();
+		})
+		after(async () => {
+			await devServer.stop();
+		})
+
+		it('loads during SSR', async () => {
+			const html = await fixture.fetch('/').then((res) => res.text());
+			const $ = cheerioLoad(html);
+			
+			// test 1: basic component renders
+			expect($('#foo > #bar').text()).to.eq('works');
+			// test 2: injects the global style on the page
+			expect($('style').first().text().replace(/\s+/g, '')).to.eq(':root{background-color:red;}');
+		});
+
+		it('does not inject styles to pages without a Vue component', async () => {
+			const html = await fixture.fetch('/unrelated').then((res) => res.text());
+			const $ = cheerioLoad(html);
+
+			expect($('style').length).to.eq(0);
+			expect($('link[rel="stylesheet"]').length).to.eq(0);
+		});
+	})
+});