Fix problem with caching (#822)

Author: spence-s

lib/handle-ts-files.ts

@@ -37,7 +37,6 @@ export async function handleTsconfig({cwd, files}: {cwd: string; files: string[]
 
 	if (unincludedFiles.length > 0) {
 		try {
-			await fs.mkdir(path.dirname(fallbackTsConfigPath), {recursive: true});
 			await fs.writeFile(fallbackTsConfigPath, JSON.stringify(tsConfig, null, 2));
 		} catch (error) {
 			console.error(error);

lib/xo.ts

@@ -1,5 +1,6 @@
 import path from 'node:path';
 import os from 'node:os';
+import fs from 'node:fs/promises';
 import process from 'node:process';
 import {ESLint, type Linter} from 'eslint';
 import findCacheDirectory from 'find-cache-directory';
@@ -127,7 +128,7 @@ export class Xo {
 	flatConfigPath?: string | undefined;
 
 	/**
-	If any user configs contains Prettier, we will need to fetch the Prettier config.
+	If any user configs contain Prettier, we will need to fetch the Prettier config.
 	*/
 	prettier?: boolean;
 
@@ -231,6 +232,25 @@ export class Xo {
 		this.xoConfig.push({ignores});
 	}
 
+	/**
+	Ensures the cache directory exists. This needs to run once before both tsconfig handling and running ESLint occur.
+
+	@private
+	*/
+	async ensureCacheDirectory() {
+		try {
+			const cacheStats = await fs.stat(this.cacheLocation);
+			// If file, re-create as directory
+			if (cacheStats.isFile()) {
+				await fs.rm(this.cacheLocation, {recursive: true, force: true});
+				await fs.mkdir(this.cacheLocation, {recursive: true});
+			}
+		} catch {
+			// If not exists, create the directory
+			await fs.mkdir(this.cacheLocation, {recursive: true});
+		}
+	}
+
 	/**
 	Checks every TS file to ensure its included in the tsconfig and any that are not included are added to a generated tsconfig for type aware linting.
 
@@ -274,6 +294,8 @@ export class Xo {
 
 		this.setIgnores();
 
+		await this.ensureCacheDirectory();
+
 		await this.handleUnincludedTsFiles(files);
 
 		this.setEslintConfig();

test/cli.test.ts

@@ -1158,3 +1158,40 @@ test('supports a custom config file with relative dot slash path for TypeScript'
 	t.true((error.stdout as string)?.includes('test.js'), 'Error should be reported for the test.js file');
 	t.true((error.stdout as string)?.includes('no-console'), 'The specific TypeScript rule should be mentioned in the output');
 });
+
+test('replaces cache file with directory when file exists at cache path', async t => {
+	const {cwd} = t.context;
+
+	// Create a simple TS file that will trigger cache creation
+	const filePath = path.join(cwd, 'test.ts');
+	await fs.writeFile(filePath, dedent`console.log('hello');\n`, 'utf8');
+
+	// Remove the default tsconfig to force cache creation
+	const tsConfigPath = path.join(cwd, 'tsconfig.json');
+	await fs.rm(tsConfigPath, {force: true});
+
+	// Create the cache directory structure up to the parent
+	const cacheParentDir = path.join(cwd, 'node_modules', '.cache');
+	await fs.mkdir(cacheParentDir, {recursive: true});
+
+	// Create a FILE at the path where XO needs to create a directory
+	const cacheDir = path.join(cacheParentDir, 'xo-linter');
+	await fs.writeFile(cacheDir, 'this is a file that should be replaced with a directory', 'utf8');
+
+	// Verify the file exists before running XO
+	const statsBeforeRun = await fs.stat(cacheDir);
+	t.true(statsBeforeRun.isFile(), 'Cache path should initially be a file');
+
+	// Run XO - this should handle the file-to-directory conversion
+	await t.notThrowsAsync($`node ./dist/cli --cwd ${cwd}`);
+
+	// Verify the cache path is now a directory
+	const statsAfterRun = await fs.stat(cacheDir);
+	t.true(statsAfterRun.isDirectory(), 'Cache path should now be a directory');
+
+	// Verify the cached tsconfig and the eslint cache file were created
+	const cachedFiles = await fs.readdir(cacheDir);
+	t.true(cachedFiles.includes('tsconfig.xo.json'), 'Cached tsconfig should exist');
+	t.true(cachedFiles.some(file => file.startsWith('.cache')), 'ESLint cache should exist');
+});
+