Adds a prefetch integration for near-instant page navigations (#3725)

* Adds a basic @astrojs/prefetch integration

* adding tests for custom selectors

* missed in last commit

* Adding a few docs, removing the option for `selectors` to be an element array

* adding an option for the concurrency limit

* fixing test for updated integration options

* Update packages/labs/prefetch/src/client.ts

Co-authored-by: Nate Moore <natemoo-re@users.noreply.github.com>

* nit: removing the NodeJS.Timer type to allow typescript to infer the return

* updating docs for default selector with ~=

* Skip prefetching on 2G connections, or when data saver is enabled

* refactor: moving to packages/integrations, Astro Labs TBD down the road

* README typo fix

Co-authored-by: Nate Moore <natemoo-re@users.noreply.github.com>

1 files changed, 31 insertions, 0 deletions

diff --git a/packages/integrations/prefetch/test/test-utils.js b/packages/integrations/prefetch/test/test-utils.js
new file mode 100644
index 000000000..198ecaafa
--- /dev/null
+++ b/packages/integrations/prefetch/test/test-utils.js
@@ -0,0 +1,31 @@
+import { test as testBase } from '@playwright/test';
+import { loadFixture as baseLoadFixture } from '../../../astro/test/test-utils.js';
+
+export function loadFixture(inlineConfig) {
+	if (!inlineConfig || !inlineConfig.root)
+		throw new Error("Must provide { root: './fixtures/...' }");
+
+	// resolve the relative root (i.e. "./fixtures/tailwindcss") to a full filepath
+	// without this, the main `loadFixture` helper will resolve relative to `packages/astro/test`
+	return baseLoadFixture({
+		...inlineConfig,
+		root: new URL(inlineConfig.root, import.meta.url).toString(),
+	});
+}
+
+export function testFactory(inlineConfig) {
+	let fixture;
+
+	const test = testBase.extend({
+		astro: async ({}, use) => {
+			fixture = await loadFixture(inlineConfig);
+			await use(fixture);
+		},
+	});
+
+	test.afterEach(() => {
+		fixture.resetAllFiles();
+	});
+
+	return test;
+}