fix: symlinks to not be resolved to real path

src/parse-tsconfig/index.ts

@@ -3,7 +3,6 @@
 import type { TsConfigJson, TsConfigJsonResolved, Cache } from '../types.js';
 import { normalizePath } from '../utils/normalize-path.js';
 import { readJsonc } from '../utils/read-jsonc.js';
-import { realpath } from '../utils/fs-cached.js';
 import { implicitBaseUrlSymbol } from '../utils/symbols.js';
 import { resolveExtendsPath } from './resolve-extends-path.js';
 
@@ -77,18 +76,11 @@
 	return extendsConfig;
 };
 
 const _parseTsconfig = (
 	tsconfigPath: string,
 	cache?: Cache<string>,
 	circularExtendsTracker = new Set<string>(),
 ): TsConfigJsonResolved => {
-	let realTsconfigPath: string;
-	try {
-		realTsconfigPath = realpath(cache, tsconfigPath) as string;
-	} catch {
-		throw new Error(`Cannot resolve tsconfig at path: ${tsconfigPath}`);
-	}
-
 	/**
 	 * Decided not to cache the TsConfigJsonResolved object because it's
 	 * mutable.
@@ -99,13 +91,18 @@
 	 *
 	 * By only caching fs results, we can avoid serving mutated objects
 	 */
-	let config: TsConfigJson = readJsonc(realTsconfigPath, cache) || {};
+	let config: TsConfigJson;
+	try {
+		config = readJsonc(tsconfigPath, cache) || {};
+	} catch {
+		throw new Error(`Cannot resolve tsconfig at path: ${tsconfigPath}`);
+	}
 
 	if (typeof config !== 'object') {
 		throw new SyntaxError(`Failed to parse tsconfig at: ${tsconfigPath}`);
 	}
 
-	const directoryPath = path.dirname(realTsconfigPath);
+	const directoryPath = path.dirname(tsconfigPath);
 
 	if (config.compilerOptions) {
 		const { compilerOptions } = config;

src/utils/fs-cached.ts

@@ -35,6 +35,5 @@ const cacheFs = <MethodName extends keyof FsMethods>(
 };
 
 export const exists = cacheFs('existsSync');
-export const realpath = cacheFs('realpathSync');
 export const readFile = cacheFs('readFileSync');
 export const stat = cacheFs('statSync');

tests/specs/get-tsconfig.ts

@@ -80,7 +80,7 @@ export default testSuite(({ describe }) => {
 			const cache = new Map();
 			const tsconfig = getTsconfig(fixture.path, 'tsconfig.json', cache);
 			expect(tsconfig).toStrictEqual(expectedResult);
-			expect(cache.size).toBe(3);
+			expect(cache.size).toBe(2);
 
 			await fixture.rm('tsconfig.json');
 

tests/specs/parse-tsconfig/extends/merges.spec.ts

@@ -1,3 +1,4 @@
+import fs from 'fs/promises';
 import path from 'path';
 import { testSuite, expect } from 'manten';
 import { createFixture } from 'fs-fixture';
@@ -220,6 +221,39 @@ export default testSuite(({ describe }) => {
 
 				expect(tsconfig).toStrictEqual(expectedTsconfig);
 			});
+
+			test('inherits from symlinked configs', async () => {
+				await using fixture = await createFixture({
+					'symlink-source': {
+						'tsconfig.base.json': createTsconfigJson({
+							include: ['../src/*'],
+						}),
+					},
+					project: {
+						src: {
+							'a.ts': '',
+							'b.ts': '',
+							'c.ts': '',
+						},
+						'tsconfig.json': createTsconfigJson({
+							extends: './symlink/tsconfig.base.json',
+						}),
+					},
+				});
+
+				await fs.symlink(fixture.getPath('symlink-source'), fixture.getPath('project/symlink'));
+
+				const expectedTsconfig = await getTscTsconfig(path.join(fixture.path, 'project'));
+				delete expectedTsconfig.files;
+
+				const tsconfig = parseTsconfig(path.join(fixture.path, 'project', 'tsconfig.json'));
+
+				expect({
+					...tsconfig,
+					// See https://github.com/privatenumber/get-tsconfig/issues/73
+					include: tsconfig.include?.map(includePath => `symlink/../${includePath}`),
+				}).toStrictEqual(expectedTsconfig);
+			});
 		});
 
 		describe('baseUrl', ({ test }) => {
@@ -309,6 +343,32 @@ export default testSuite(({ describe }) => {
 				const tsconfig = parseTsconfig(path.join(fixture.path, 'tsconfig.json'));
 				expect(tsconfig).toStrictEqual(expectedTsconfig);
 			});
+
+			test('resolves parent baseUrl path defined in symlinked config', async () => {
+				await using fixture = await createFixture({
+					'symlink-source': {
+						'tsconfig.json': createTsconfigJson({
+							compilerOptions: {
+								baseUrl: '..',
+							},
+						}),
+					},
+					project: {
+						'tsconfig.json': createTsconfigJson({
+							extends: './symlink/tsconfig.json',
+						}),
+						'a.ts': '',
+					},
+				});
+
+				await fs.symlink(fixture.getPath('symlink-source'), fixture.getPath('project/symlink'));
+
+				const expectedTsconfig = await getTscTsconfig(path.join(fixture.path, 'project'));
+				delete expectedTsconfig.files;
+
+				const tsconfig = parseTsconfig(path.join(fixture.path, 'project', 'tsconfig.json'));
+				expect(tsconfig).toStrictEqual(expectedTsconfig);
+			});
 		});
 
 		test('nested extends', async () => {

tests/specs/parse-tsconfig/extends/resolves/index.ts

@@ -84,5 +84,6 @@ export default testSuite(({ describe }) => {
 		runTestSuite(import('./relative-path.spec.js'));
 		runTestSuite(import('./absolute-path.spec.js'));
 		runTestSuite(import('./node-modules.spec.js'));
+		runTestSuite(import('./symbolic-link.spec.js'));
 	});
 });

tests/specs/parse-tsconfig/extends/resolves/symbolic-link.spec.ts

@@ -0,0 +1,122 @@
+import fs from 'fs/promises';
+import path from 'path';
+import { testSuite, expect } from 'manten';
+import { createFixture } from 'fs-fixture';
+import { createTsconfigJson, getTscTsconfig } from '../../../../utils.js';
+import { parseTsconfig } from '#get-tsconfig';
+
+const validate = async (directoryPath: string) => {
+	const expectedTsconfig = await getTscTsconfig(directoryPath);
+	delete expectedTsconfig.files;
+
+	const tsconfig = parseTsconfig(path.join(directoryPath, 'tsconfig.json'));
+	expect(tsconfig).toStrictEqual(expectedTsconfig);
+};
+
+export default testSuite(({ describe }) => {
+	describe('symbolic link', ({ test }) => {
+		test('extends symlink to file', async () => {
+			await using fixture = await createFixture({
+				'tsconfig.symlink-source.json': createTsconfigJson({
+					compilerOptions: {
+						jsx: 'react',
+						allowJs: true,
+					},
+				}),
+				'tsconfig.json': createTsconfigJson({
+					extends: './tsconfig.symlink.json',
+					compilerOptions: {
+						strict: true,
+					},
+				}),
+				'file.ts': '',
+			});
+
+			await fs.symlink(fixture.getPath('tsconfig.symlink-source.json'), fixture.getPath('tsconfig.symlink.json'));
+
+			await validate(fixture.path);
+		});
+
+		test('extends file from symlink to directory', async () => {
+			await using fixture = await createFixture({
+				'symlink-source': {
+					'tsconfig.json': createTsconfigJson({
+						compilerOptions: {
+							jsx: 'react',
+							allowJs: true,
+						},
+					}),
+				},
+				'tsconfig.json': createTsconfigJson({
+					extends: './symlink/tsconfig.json',
+					compilerOptions: {
+						strict: true,
+					},
+				}),
+				'file.ts': '',
+			});
+
+			await fs.symlink(fixture.getPath('symlink-source'), fixture.getPath('symlink'));
+
+			await validate(fixture.path);
+		});
+
+		test('extends from symlink to file in origin directory', async () => {
+			await using fixture = await createFixture({
+				'symlink-source': {
+					'tsconfig.main.json': createTsconfigJson({
+						extends: './tsconfig.base.json',
+						compilerOptions: {
+							strict: true,
+						},
+					}),
+				},
+				project: {
+					'tsconfig.base.json': createTsconfigJson({
+						compilerOptions: {
+							jsx: 'react',
+							allowJs: true,
+						},
+					}),
+					'file.ts': '',
+				},
+			});
+
+			await fs.symlink(fixture.getPath('symlink-source/tsconfig.main.json'), fixture.getPath('project/tsconfig.json'));
+
+			await validate(fixture.getPath('project'));
+		});
+
+		test('extends from file in symlinked directory to file in origin directory', async () => {
+			await using fixture = await createFixture({
+				'symlink-source': {
+					'tsconfig.main.json': createTsconfigJson({
+						extends: '../tsconfig.base.json',
+						compilerOptions: {
+							strict: true,
+						},
+					}),
+				},
+				project: {
+					'tsconfig.base.json': createTsconfigJson({
+						compilerOptions: {
+							jsx: 'react',
+							allowJs: true,
+						},
+					}),
+					'tsconfig.json': createTsconfigJson({
+						extends: './symlink/tsconfig.main.json',
+						compilerOptions: {
+							importHelpers: true,
+						},
+					}),
+					'file.ts': '',
+				},
+			});
+
+			await fs.symlink(fixture.getPath('symlink-source'), fixture.getPath('project/symlink'));
+
+			await validate(fixture.getPath('project'));
+		});
+	});
+});

tests/specs/parse-tsconfig/parses.spec.ts

@@ -146,15 +146,15 @@ export default testSuite(({ describe }) => {
 
 			const cache = new Map();
 			const parsedTsconfig = parseTsconfig(path.join(fixture.path, 'tsconfig.json'), cache);
-			expect(cache.size).toBe(2);
+			expect(cache.size).toBe(1);
 
 			const expectedTsconfig = await getTscTsconfig(fixture.path);
 			delete expectedTsconfig.files;
 
 			expect(parsedTsconfig).toStrictEqual(expectedTsconfig);
 
 			const parsedTsconfigCached = parseTsconfig(path.join(fixture.path, 'tsconfig.json'), cache);
-			expect(cache.size).toBe(2);
+			expect(cache.size).toBe(1);
 
 			expect(parsedTsconfigCached).toStrictEqual(expectedTsconfig);
 		});