From 2130bb6b17b067325970a60dda408aa4a22941a7 Mon Sep 17 00:00:00 2001
From: Alex Pshul <alex@pshul.com>
Date: Mon, 7 Oct 2024 20:20:37 -0400
Subject: [PATCH] Added eslint flat config support to init generator

---
 .../func/src/generators/init/generator.ts     | 47 ++++++++++++++++---
 .../src/generators/init/tests/eslint.spec.ts  | 30 +++++++++++-
 2 files changed, 68 insertions(+), 9 deletions(-)

diff --git a/packages/func/src/generators/init/generator.ts b/packages/func/src/generators/init/generator.ts
index 1400197..bfcc835 100644
--- a/packages/func/src/generators/init/generator.ts
+++ b/packages/func/src/generators/init/generator.ts
@@ -204,9 +204,7 @@ const createRegisterPathsFile = (tree: Tree, { appRoot }: NormalizedOptions) =>
   );
 };
 
-const configureEslint = (tree: Tree, { appRoot, appNames: { name } }: NormalizedOptions) => {
-  if (!tree.exists('.eslintrc.json')) return;
-
+const setupEslintrc = (tree: Tree, appRoot: string) => {
   const relativePathToRoot = offsetFromRoot(appRoot);
   const projectJsonPath = `${appRoot}/tsconfig.*?.json`;
 
@@ -234,13 +232,48 @@ const configureEslint = (tree: Tree, { appRoot, appNames: { name } }: Normalized
   };
 
   tree.write(path.posix.join(appRoot, '.eslintrc.json'), JSON.stringify(projectEslintConfig, null, 2));
+};
+
+const setupFlatEslintConfig = (tree: Tree, appRoot: string, fileName: string) => {
+  const relativePathToRoot = offsetFromRoot(appRoot);
+  const projectJsonPath = path.posix.normalize(`${fileName}/tsconfig.*?.json`);
+
+  const configFileContent = `
+    const baseConfig = require('${relativePathToRoot}eslint.config.js');
+
+    module.exports = [
+      ...baseConfig,
+      { rules: {} },
+      {
+        files: ['**/*.ts', '**/*.tsx', '**/*.js', '**/*.jsx'],
+        // Override or add rules here
+        rules: {},
+        languageOptions: { parserOptions: { project: [${path.posix.join(...projectJsonPath.split(path.sep))}], } },
+      },
+      {
+        files: ['**/*.ts', '**/*.tsx'],
+        // Override or add rules here
+        rules: {},
+      },
+      {
+        files: ['**/*.js', '**/*.jsx'],
+        // Override or add rules here
+        rules: {},
+      },
+    ];
+  `;
+
+  tree.write(path.posix.join(appRoot, 'eslint.config.js'), configFileContent);
+};
+
+const configureEslint = (tree: Tree, { appRoot, appNames: { name, fileName } }: NormalizedOptions) => {
+  if (tree.exists('.eslintrc.json')) setupEslintrc(tree, appRoot);
+  else if (tree.exists('eslint.config.js')) setupFlatEslintConfig(tree, appRoot, fileName);
+  else return;
 
   const projectConfig = readProjectConfiguration(tree, name);
   projectConfig.targets.lint = {
-    executor: '@nx/linter:eslint',
-    options: {
-      lintFilePatterns: [`apps/${name}/**/*.ts`],
-    },
+    executor: '@nx/eslint:lint',
     outputs: ['{options.outputFile}'],
   };
 
diff --git a/packages/func/src/generators/init/tests/eslint.spec.ts b/packages/func/src/generators/init/tests/eslint.spec.ts
index ce155b9..2a47eaf 100644
--- a/packages/func/src/generators/init/tests/eslint.spec.ts
+++ b/packages/func/src/generators/init/tests/eslint.spec.ts
@@ -26,18 +26,23 @@ describe('Init with no eslint', () => {
   it(
     'No global config -> no app config',
     async () => {
-      await generator(appTree, { ...baseOptions, name: baseOptions.name + '1' });
+      const name = baseOptions.name + '1';
+      await generator(appTree, { ...baseOptions, name });
 
       const eslintConfigExists = appTree.exists('apps/hello-world1/.eslintrc.json');
       expect(eslintConfigExists).toBeFalsy();
+
+      const projectConfiguration = readProjectConfiguration(appTree, name);
+      expect(projectConfiguration).not.toHaveProperty('targets.lint');
     },
     TEST_TIMEOUT,
   );
 
   it(
-    'Global config exists -> app config generated',
+    'Global old config exists -> app config generated',
     async () => {
       appTree.write('.eslintrc.json', JSON.stringify({}));
+
       const name = baseOptions.name + '2';
       await generator(appTree, { ...baseOptions, name });
 
@@ -46,6 +51,27 @@ describe('Init with no eslint', () => {
 
       const projectConfiguration = readProjectConfiguration(appTree, name);
       expect(projectConfiguration).toHaveProperty('targets.lint');
+
+      appTree.delete('.eslintrc.json');
+    },
+    TEST_TIMEOUT,
+  );
+
+  it(
+    'Global flat config exists -> app config generated',
+    async () => {
+      appTree.write('eslint.config.js', '');
+
+      const name = baseOptions.name + '3';
+      await generator(appTree, { ...baseOptions, name });
+
+      const eslintConfigExists = appTree.exists('apps/hello-world3/eslint.config.js');
+      expect(eslintConfigExists).toBeTruthy();
+
+      const projectConfiguration = readProjectConfiguration(appTree, name);
+      expect(projectConfiguration).toHaveProperty('targets.lint');
+
+      appTree.delete('eslint.config.js');
     },
     TEST_TIMEOUT,
   );