feat: add fallback option to avoid meaningless result.

Author: emosheeep

src/paths-matcher/index.ts

@@ -1,6 +1,6 @@
 import path from 'path';
 import slash from 'slash';
-import type { TsConfigResult } from '../types.js';
+import type { MatchOptions, TsConfigResult } from '../types.js';
 import { isRelativePathPattern } from '../utils/is-relative-path-pattern.js';
 import { implicitBaseUrlSymbol } from '../utils/symbols.js';
 import {
@@ -40,6 +40,7 @@ const parsePaths = (
  */
 export const createPathsMatcher = (
 	tsconfig: TsConfigResult,
+	{ fallback = true }: MatchOptions = {},
 ) => {
 	if (!tsconfig.config.compilerOptions) {
 		return null;
@@ -97,7 +98,7 @@ export const createPathsMatcher = (
 
 		if (!matchedValue) {
 			return (
-				baseUrl
+				(baseUrl && fallback)
 					? [slash(path.join(resolvedBaseUrl, specifier))]
 					: []
 			);

src/types.ts

@@ -15,3 +15,12 @@ export type TsConfigResult = {
 	 */
 	config: TsConfigJsonResolved;
 };
+
+export type MatchOptions = {
+	/**
+	 * Fallback to joined path.
+	 * @description Return `path.join(baseUrl, specifier)` if the specifier matches nothing
+	 * @default true
+	 */
+	fallback?: boolean;
+}

tests/specs/create-paths-matcher.ts

@@ -427,6 +427,32 @@ export default testSuite(({ describe }) => {
 			await fixture.rm();
 		});
 
+		test('fallback option', async () => {
+			const fixture = await createFixture({
+				'tsconfig.json': createTsconfigJson({
+					compilerOptions: {
+						paths: {
+							'@test': ['./test'],
+						},
+					},
+				}),
+			});
+
+			const tsconfig = getTsconfig(fixture.path);
+			expect(tsconfig).not.toBeNull();
+
+			const testmatcher = createPathsMatcher(tsconfig!)!;
+			const mismatcher = createPathsMatcher(tsconfig!, { fallback: false })!;
+
+			expect(mismatcher('@mismatch')).toStrictEqual([]);
+			const resolvedAttempts = await getTscResolution('@test', fixture.path);
+			expect(testmatcher('@test')).toStrictEqual([
+				resolvedAttempts[0].filePath.slice(0, -3),
+			]);
+
+			await fixture.rm();
+		});
+
 		test('matches absolute paths', async () => {
 			const fixture = await createFixture({
 				'tsconfig.json': createTsconfigJson({