From 96bc59680c7300ab6f4f740da26fa16e1970c7c0 Mon Sep 17 00:00:00 2001
From: Hiroki Osame <hiroki.osame@gmail.com>
Date: Sat, 4 May 2024 22:57:56 +0900
Subject: [PATCH] fix(tsImport): handle importing packages (#14)

---
 src/esm/hook/resolve.ts | 51 +++++++++++++++++++++++------------------
 tests/specs/api.ts      | 12 ++++++++--
 2 files changed, 39 insertions(+), 24 deletions(-)

diff --git a/src/esm/hook/resolve.ts b/src/esm/hook/resolve.ts
index 8a36e55b..cefb97bd 100644
--- a/src/esm/hook/resolve.ts
+++ b/src/esm/hook/resolve.ts
@@ -121,6 +121,35 @@ export const resolve: resolve = async (
 		return nextResolve(specifier, context);
 	}
 
+	const isPath = (
+		specifier.startsWith(fileProtocol)
+		|| isRelativePathPattern.test(specifier)
+	);
+
+	// bare specifier
+	if (!isPath) {
+		// TS path alias
+		if (
+			tsconfigPathsMatcher
+			&& !context.parentURL?.includes('/node_modules/')
+		) {
+			const possiblePaths = tsconfigPathsMatcher(specifier);
+			for (const possiblePath of possiblePaths) {
+				try {
+					return await resolve(
+						pathToFileURL(possiblePath).toString(),
+						context,
+						nextResolve,
+					);
+				} catch {}
+			}
+		}
+
+		// npm package -- use default resolution
+		return nextResolve(specifier, context);
+	}
+
+	// Inherit namespace from parent
 	let requestNamespace = getNamespace(specifier);
 	if (context.parentURL) {
 		const parentNamespace = getNamespace(context.parentURL);
@@ -139,28 +168,6 @@ export const resolve: resolve = async (
 		return await tryDirectory(specifier, context, nextResolve);
 	}
 
-	const isPath = (
-		specifier.startsWith(fileProtocol)
-		|| isRelativePathPattern.test(specifier)
-	);
-
-	if (
-		tsconfigPathsMatcher
-		&& !isPath // bare specifier
-		&& !context.parentURL?.includes('/node_modules/')
-	) {
-		const possiblePaths = tsconfigPathsMatcher(specifier);
-		for (const possiblePath of possiblePaths) {
-			try {
-				return await resolve(
-					pathToFileURL(possiblePath).toString(),
-					context,
-					nextResolve,
-				);
-			} catch {}
-		}
-	}
-
 	// Typescript gives .ts, .cts, or .mts priority over actual .js, .cjs, or .mjs extensions
 	//
 	// If `allowJs` is set in `tsconfig.json`, then we'll apply the same resolution logic
diff --git a/tests/specs/api.ts b/tests/specs/api.ts
index 63e20152..0e330764 100644
--- a/tests/specs/api.ts
+++ b/tests/specs/api.ts
@@ -20,7 +20,15 @@ const tsFiles = {
 	import { bar } from './bar.js'
 	export const foo = \`foo \${bar}\` as string
 	`,
-	'bar.ts': 'export const bar = "bar" as string',
+	'bar.ts': 'export type A = 1; export { bar } from "pkg"',
+	'node_modules/pkg': {
+		'package.json': JSON.stringify({
+			name: 'pkg',
+			type: 'module',
+			exports: './index.js',
+		}),
+		'index.js': 'export const bar = "bar"',
+	},
 };
 
 export default testSuite(({ describe }, node: NodeApis) => {
@@ -244,7 +252,7 @@ export default testSuite(({ describe }, node: NodeApis) => {
 							nodePath: node.path,
 							nodeOptions: [],
 						});
-						expect(stdout).toBe('file.ts\nfoo.ts\nbar.ts');
+						expect(stdout).toBe('file.ts\nfoo.ts\nbar.ts\nindex.js');
 					});
 				});