fix: allow extends array to have common dependency (#68)

Co-authored-by: Hiroki Osame <hiroki.osame@gmail.com>

Author: 13OnTheCode

src/parse-tsconfig/index.ts

@@ -133,7 +133,7 @@ const _parseTsconfig = (
 			const extendsConfig = resolveExtends(
 				extendsPath,
 				directoryPath,
-				circularExtendsTracker,
+				new Set(circularExtendsTracker),
 				cache,
 			);
 			const merged = {

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

@@ -1,11 +1,11 @@
 import path from 'path';
 import { testSuite, expect } from 'manten';
 import { createFixture } from 'fs-fixture';
-import { createTsconfigJson } from '../../../../utils.js';
+import { createTsconfigJson, getTscTsconfig } from '../../../../utils.js';
 import { parseTsconfig } from '#get-tsconfig';
 
 export default testSuite(({ describe }) => {
-	describe('resolves', ({ test, runTestSuite }) => {
+	describe('resolves', ({ test, describe, runTestSuite }) => {
 		test('handles missing extends', async () => {
 			const fixture = await createFixture({
 				'file.ts': '',
@@ -21,6 +21,70 @@ export default testSuite(({ describe }) => {
 			await fixture.rm();
 		});
 
+		describe('circularity', ({ test }) => {
+			test('self extend', async ({ onTestFinish }) => {
+				const fixture = await createFixture({
+					'tsconfig.json': createTsconfigJson({
+						extends: './tsconfig.json',
+					}),
+					'file.ts': '',
+				});
+				onTestFinish(() => fixture.rm());
+
+				const errorMessage = 'Circularity detected while resolving configuration';
+				await expect(
+					getTscTsconfig(fixture.path),
+				).rejects.toThrow(errorMessage);
+				expect(
+					() => parseTsconfig(path.join(fixture.path, 'tsconfig.json')),
+				).toThrow(errorMessage);
+
+				await fixture.rm();
+			});
+
+			test('recursive', async ({ onTestFinish }) => {
+				const fixture = await createFixture({
+					'base.json': createTsconfigJson({
+						extends: './tsconfig.json',
+					}),
+					'tsconfig.json': createTsconfigJson({
+						extends: './base.json',
+					}),
+				});
+				onTestFinish(() => fixture.rm());
+
+				expect(
+					() => parseTsconfig(path.join(fixture.path, 'tsconfig.json')),
+				).toThrow('Circularity detected while resolving configuration:');
+			});
+		});
+
+		test('extends array with common base', async ({ onTestFinish }) => {
+			const fixture = await createFixture({
+				'base.json': createTsconfigJson({}),
+				'tsconfig-b.json': createTsconfigJson({
+					extends: './base.json',
+				}),
+				'tsconfig-a.json': createTsconfigJson({
+					extends: './base.json',
+				}),
+				'tsconfig.json': createTsconfigJson({
+					extends: [
+						'./tsconfig-a.json',
+						'./tsconfig-b.json',
+					],
+				}),
+				'file.ts': '',
+			});
+			onTestFinish(() => fixture.rm());
+
+			const expectedTsconfig = await getTscTsconfig(fixture.path);
+			delete expectedTsconfig.files;
+
+			const tsconfig = parseTsconfig(path.join(fixture.path, 'tsconfig.json'));
+			expect(tsconfig).toStrictEqual(expectedTsconfig);
+		});
+
 		runTestSuite(import('./relative-path.spec.js'));
 		runTestSuite(import('./absolute-path.spec.js'));
 		runTestSuite(import('./node-modules.spec.js'));

tests/specs/parse-tsconfig/extends/resolves/relative-path.spec.ts

@@ -190,24 +190,5 @@ export default testSuite(({ describe }) => {
 
 			await fixture.rm();
 		});
-
-		test('circular extends', async () => {
-			const fixture = await createFixture({
-				'tsconfig.json': createTsconfigJson({
-					extends: './tsconfig.json',
-				}),
-				'file.ts': '',
-			});
-
-			const errorMessage = 'Circularity detected while resolving configuration';
-			await expect(
-				getTscTsconfig(fixture.path),
-			).rejects.toThrow(errorMessage);
-			expect(
-				() => parseTsconfig(path.join(fixture.path, 'tsconfig.json')),
-			).toThrow(errorMessage);
-
-			await fixture.rm();
-		});
 	});
 });