Finish backlog cleanup for Pi integration

tests/pi-extension-loader-patch.test.ts

@@ -0,0 +1,42 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+
+import { patchPiExtensionLoaderSource } from "../scripts/lib/pi-extension-loader-patch.mjs";
+
+test("patchPiExtensionLoaderSource rewrites Windows extension imports to file URLs", () => {
+	const input = [
+		'import * as path from "node:path";',
+		'import { fileURLToPath } from "node:url";',
+		"async function loadExtensionModule(extensionPath) {",
+		"    const jiti = createJiti(import.meta.url);",
+		'    const module = await jiti.import(extensionPath, { default: true });',
+		"    return module;",
+		"}",
+		"",
+	].join("\n");
+
+	const patched = patchPiExtensionLoaderSource(input);
+
+	assert.match(patched, /pathToFileURL/);
+	assert.match(patched, /process\.platform === "win32"/);
+	assert.match(patched, /path\.isAbsolute\(extensionPath\)/);
+	assert.match(patched, /jiti\.import\(extensionSpecifier, \{ default: true \}\)/);
+});
+
+test("patchPiExtensionLoaderSource is idempotent", () => {
+	const input = [
+		'import * as path from "node:path";',
+		'import { fileURLToPath } from "node:url";',
+		"async function loadExtensionModule(extensionPath) {",
+		"    const jiti = createJiti(import.meta.url);",
+		'    const module = await jiti.import(extensionPath, { default: true });',
+		"    return module;",
+		"}",
+		"",
+	].join("\n");
+
+	const once = patchPiExtensionLoaderSource(input);
+	const twice = patchPiExtensionLoaderSource(once);
+
+	assert.equal(twice, once);
+});