Fix tsconfig resolution quirks (#683)

Author: spence-s

.gitignore

@@ -4,5 +4,7 @@ yarn.lock
 test/fixtures/project/node_modules/.cache
 !test/fixtures/typescript/extends-module/node_modules
 test/fixtures/typescript/extends-module/node_modules/.cache
+!test/fixtures/typescript/extends-tsconfig-bases/node_modules
+test/fixtures/typescript/extends-tsconfig-bases/node_modules/.cache
 .nyc_output
 coverage

lib/options-manager.js

@@ -28,7 +28,7 @@ import {
 	CACHE_DIR_NAME,
 } from './constants.js';
 
-const {__dirname, readJson, require} = createEsmUtils(import.meta);
+const {__dirname, require} = createEsmUtils(import.meta);
 const {normalizePackageName} = Legacy.naming;
 const resolveModule = Legacy.ModuleResolver.resolve;
 
@@ -162,7 +162,7 @@ const handleTSConfig = async options => {
 
 	if (tsConfigProjectPath) {
 		options.tsConfigPath = path.resolve(options.cwd, tsConfigProjectPath);
-		options.tsConfig = await readJson(options.tsConfigPath);
+		options.tsConfig = JSON5.parse(await fs.readFile(options.tsConfigPath));
 	} else {
 		const tsConfigExplorer = cosmiconfig([], {
 			searchPlaces: ['tsconfig.json'],
@@ -644,9 +644,22 @@ async function recursiveBuildTsConfig(tsConfig, tsConfigPath) {
 	}
 
 	// If any of the following are missing, then we need to look up the base config as it could apply
-	// Use node resolution
 	const require = createRequire(tsConfigPath);
-	const basePath = require.resolve(tsConfig.extends);
+
+	let basePath;
+	try {
+		basePath = require.resolve(tsConfig.extends);
+	} catch (error) {
+		// Tsconfig resolution is odd, It allows behavior that is not exactly like node resolution
+		// therefore we attempt to smooth this out here with this hack
+		try {
+			basePath = require.resolve(path.join(tsConfig.extends, 'tsconfig.json'));
+		} catch {
+			// Throw the orginal resolution error to let the user know their extends block is invalid
+			throw error;
+		}
+	}
+
 	const baseTsConfig = JSON5.parse(await fs.readFile(basePath));
 
 	delete tsConfig.extends;

test/fixtures/typescript/extends-tsconfig-bases/node_modules/@tsconfig/node16/package.json

@@ -0,0 +1,3 @@
+{
+	"xo": {}
+}

test/fixtures/typescript/extends-tsconfig-bases/node_modules/@tsconfig/node16/tsconfig.json

@@ -0,0 +1,3 @@
+{
+	"extends": "@tsconfig/node16"
+}

test/fixtures/typescript/extends-tsconfig-bases/package.json

@@ -680,6 +680,15 @@ test('mergeWithFileConfig: tsconfig can properly extend configs in node_modules'
 	t.is(options.tsConfigPath, expectedConfigPath);
 });
 
+test('mergeWithFileConfig: tsconfig can properly extend tsconfig base node_modules', async t => {
+	const cwd = path.resolve('fixtures', 'typescript', 'extends-tsconfig-bases');
+	const expectedConfigPath = path.join(cwd, 'tsconfig.json');
+	const filePath = path.resolve(cwd, 'does-not-matter.ts');
+	await t.notThrowsAsync(manager.mergeWithFileConfig({cwd, filePath}));
+	const {options} = await manager.mergeWithFileConfig({cwd, filePath});
+	t.is(options.tsConfigPath, expectedConfigPath);
+});
+
 test('applyOverrides', t => {
 	t.deepEqual(
 		manager.applyOverrides(