From 1cf11989411cc20cbf1a48476306649d9492a4ce Mon Sep 17 00:00:00 2001
From: Nate Moore <nate@astro.build>
Date: Wed, 20 Dec 2023 15:07:34 -0600
Subject: [PATCH] feat: add resolveEntrypoint utility

---
 packages/internal-helpers/package.json      |  9 ++++-
 packages/internal-helpers/src/path.ts       | 17 +++++++++
 packages/internal-helpers/test/path.test.js | 41 +++++++++++++++++++++
 pnpm-lock.yaml                              | 15 +++++++-
 4 files changed, 78 insertions(+), 4 deletions(-)
 create mode 100644 packages/internal-helpers/test/path.test.js

diff --git a/packages/internal-helpers/package.json b/packages/internal-helpers/package.json
index 650665bfe5..120b1a48a8 100644
--- a/packages/internal-helpers/package.json
+++ b/packages/internal-helpers/package.json
@@ -29,10 +29,15 @@
     "build": "astro-scripts build \"src/**/*.ts\" && tsc -p tsconfig.json",
     "build:ci": "astro-scripts build \"src/**/*.ts\"",
     "postbuild": "astro-scripts copy \"src/**/*.js\"",
-    "dev": "astro-scripts dev \"src/**/*.ts\""
+    "dev": "astro-scripts dev \"src/**/*.ts\"",
+    "test": "mocha --exit --timeout 20000"
   },
   "devDependencies": {
-    "astro-scripts": "workspace:*"
+    "@types/chai": "^4.3.10",
+    "@types/mocha": "^10.0.4",
+    "astro-scripts": "workspace:*",
+    "chai": "^4.3.7",
+    "mocha": "^10.2.0"
   },
   "keywords": [
     "astro",
diff --git a/packages/internal-helpers/src/path.ts b/packages/internal-helpers/src/path.ts
index cc9954ef2c..eee3bffe9e 100644
--- a/packages/internal-helpers/src/path.ts
+++ b/packages/internal-helpers/src/path.ts
@@ -56,6 +56,23 @@ export function isRelativePath(path: string) {
 	return startsWithDotDotSlash(path) || startsWithDotSlash(path);
 }
 
+function createRootRelativePath(value: URL, root: URL) {
+	return '/' + removeLeadingForwardSlash(value.toString().replace(root.toString(), ''));
+}
+
+export function resolveEntrypoint(entrypoint: string | URL, root: URL) {
+	if (entrypoint instanceof URL) {
+		return createRootRelativePath(entrypoint, root);
+	}
+	if (startsWithForwardSlash(entrypoint)) {
+		return entrypoint;
+	}
+	if (isRelativePath(entrypoint)) {
+		return createRootRelativePath(new URL(entrypoint, root), root);
+	}
+	return entrypoint;
+}
+
 function isString(path: unknown): path is string {
 	return typeof path === 'string' || path instanceof String;
 }
diff --git a/packages/internal-helpers/test/path.test.js b/packages/internal-helpers/test/path.test.js
new file mode 100644
index 0000000000..87814eae73
--- /dev/null
+++ b/packages/internal-helpers/test/path.test.js
@@ -0,0 +1,41 @@
+import { resolveEntrypoint } from '../dist/path.js';
+import { expect } from 'chai';
+
+describe('resolveEntrypoint', () => {
+	it('handles fully resolved URLs', () => {
+		const root = new URL('file://test/path/usr/');
+		const entrypoint = new URL('./src/item.ts', root);
+		const output = resolveEntrypoint(entrypoint, root);
+		expect(output).to.equal('/src/item.ts');
+	})
+	it('handles relative paths', () => {
+		const root = new URL('file://test/path/usr/');
+		const entrypoint = './src/item.ts';
+		const output = resolveEntrypoint(entrypoint, root);
+		expect(output).to.equal('/src/item.ts');
+	})
+	it('handles root-relative specifiers', () => {
+		const root = new URL('file://test/path/usr/');
+		const entrypoint = '/src/item.ts';
+		const output = resolveEntrypoint(entrypoint, root);
+		expect(output).to.equal('/src/item.ts');
+	})
+	it('handles virtual modules', () => {
+		const root = new URL('file://test/path/usr/');
+		const entrypoint = 'virtual:test-entrypoint';
+		const output = resolveEntrypoint(entrypoint, root);
+		expect(output).to.equal(entrypoint);
+	})
+	it('handles fully resolved node_modules paths', () => {
+		const root = new URL('file://test/path/usr/');
+		const entrypoint = new URL('file://test/path/usr/node_modules/@astrojs/preact/dist/server.js');
+		const output = resolveEntrypoint(entrypoint, root);
+		expect(output).to.equal('/node_modules/@astrojs/preact/dist/server.js');
+	})
+	it('handles package specifier', () => {
+		const root = new URL('file://test/path/usr/');
+		const entrypoint = '@astrojs/preact/server';
+		const output = resolveEntrypoint(entrypoint, root);
+		expect(output).to.equal(entrypoint);
+	})
+});
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index ac222b3274..dd55ba0be5 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -4871,9 +4871,21 @@ importers:
 
   packages/internal-helpers:
     devDependencies:
+      '@types/chai':
+        specifier: ^4.3.10
+        version: 4.3.10
+      '@types/mocha':
+        specifier: ^10.0.4
+        version: 10.0.4
       astro-scripts:
         specifier: workspace:*
         version: link:../../scripts
+      chai:
+        specifier: ^4.3.7
+        version: 4.3.10
+      mocha:
+        specifier: ^10.2.0
+        version: 10.2.0
 
   packages/markdown/remark:
     dependencies:
@@ -7308,12 +7320,11 @@ packages:
   /@types/chai-subset@1.3.4:
     resolution: {integrity: sha512-CCWNXrJYSUIojZ1149ksLl3AN9cmZ5djf+yUoVVV+NuYrtydItQVlL2ZDqyC6M6O9LWRnVf8yYDxbXHO2TfQZg==}
     dependencies:
-      '@types/chai': 4.3.9
+      '@types/chai': 4.3.10
     dev: false
 
   /@types/chai@4.3.10:
     resolution: {integrity: sha512-of+ICnbqjmFCiixUnqRulbylyXQrPqIGf/B3Jax1wIF3DvSheysQxAWvqHhZiW3IQrycvokcLcFQlveGp+vyNg==}
-    dev: true
 
   /@types/chai@4.3.9:
     resolution: {integrity: sha512-69TtiDzu0bcmKQv3yg1Zx409/Kd7r0b5F1PfpYJfSHzLGtB53547V4u+9iqKYsTu/O2ai6KTb0TInNpvuQ3qmg==}