fix(misc): handle flat pre-defined flat configs when migrating to mon…

…orepo-style

packages/eslint/src/generators/init/init-migration.ts

@@ -23,6 +23,7 @@ import {
   generateSpreadElement,
   removeCompatExtends,
   removePlugin,
+  removePredefinedConfigs,
 } from '../utils/flat-config/ast-utils';
 import { hasEslintPlugin } from '../utils/plugin';
 import { ESLINT_CONFIG_FILENAMES } from '../../utils/config-file';
@@ -152,6 +153,11 @@ function migrateEslintFile(projectEslintPath: string, tree: Tree) {
         'plugin:@nrwl/typescript',
         'plugin:@nrwl/javascript',
       ]);
+      config = removePredefinedConfigs(config, '@nx/eslint-plugin', 'nx', [
+        'flat/base',
+        'flat/typescript',
+        'flat/javascript',
+      ]);
       tree.write(projectEslintPath, config);
     } else {
       updateJson(tree, projectEslintPath, (json) => {

packages/eslint/src/generators/utils/flat-config/ast-utils.spec.ts

@@ -7,10 +7,13 @@ import {
   generateFlatOverride,
   generatePluginExtendsElementWithCompatFixup,
   removeCompatExtends,
+  removeImportFromFlatConfig,
   removeOverridesFromLintConfig,
   removePlugin,
+  removePredefinedConfigs,
   replaceOverride,
 } from './ast-utils';
+import { stripIndents } from '@nx/devkit';
 
 describe('ast-utils', () => {
   const printer = ts.createPrinter();
@@ -341,6 +344,32 @@ describe('ast-utils', () => {
     });
   });
 
+  describe('removeImportFromFlatConfig', () => {
+    it('should remove existing import from config if the var name matches', () => {
+      const content = stripIndents`
+        const nx = require("@nx/eslint-plugin");
+        const thisShouldRemain = require("@nx/eslint-plugin");
+        const playwright = require('eslint-plugin-playwright');
+        module.exports = [
+          playwright.configs['flat/recommended'],
+        ];
+      `;
+      const result = removeImportFromFlatConfig(
+        content,
+        'nx',
+        '@nx/eslint-plugin'
+      );
+      expect(result).toMatchInlineSnapshot(`
+        "
+        const thisShouldRemain = require("@nx/eslint-plugin");
+        const playwright = require('eslint-plugin-playwright');
+        module.exports = [
+        playwright.configs['flat/recommended'],
+        ];"
+      `);
+    });
+  });
+
   describe('addCompatToFlatConfig', () => {
     it('should add compat to config', () => {
       const content = `const baseConfig = require("../../eslint.config.js");
@@ -966,6 +995,66 @@ describe('ast-utils', () => {
     });
   });
 
+  describe('removePredefinedConfigs', () => {
+    it('should remove config objects and import', () => {
+      const content = stripIndents`
+        const nx = require("@nx/eslint-plugin");
+        const playwright = require('eslint-plugin-playwright');
+        module.exports = [
+          ...nx.config['flat/base'],
+          ...nx.config['flat/typescript'],
+          ...nx.config['flat/javascript'],
+          playwright.configs['flat/recommended'],
+        ];
+      `;
+
+      const result = removePredefinedConfigs(
+        content,
+        '@nx/eslint-plugin',
+        'nx',
+        ['flat/base', 'flat/typescript', 'flat/javascript']
+      );
+
+      expect(result).toMatchInlineSnapshot(`
+        "
+        const playwright = require('eslint-plugin-playwright');
+        module.exports = [
+        playwright.configs['flat/recommended'],
+        ];"
+      `);
+    });
+
+    it('should keep configs that are not in the list', () => {
+      const content = stripIndents`
+        const nx = require("@nx/eslint-plugin");
+        const playwright = require('eslint-plugin-playwright');
+        module.exports = [
+          ...nx.config['flat/base'],
+          ...nx.config['flat/typescript'],
+          ...nx.config['flat/javascript'],
+          ...nx.config['flat/react'],
+          playwright.configs['flat/recommended'],
+        ];
+      `;
+
+      const result = removePredefinedConfigs(
+        content,
+        '@nx/eslint-plugin',
+        'nx',
+        ['flat/base', 'flat/typescript', 'flat/javascript']
+      );
+
+      expect(result).toMatchInlineSnapshot(`
+        "const nx = require("@nx/eslint-plugin");
+        const playwright = require('eslint-plugin-playwright');
+        module.exports = [
+        ...nx.config['flat/react'],
+        playwright.configs['flat/recommended'],
+        ];"
+      `);
+    });
+  });
+
   describe('generatePluginExtendsElementWithCompatFixup', () => {
     it('should return spread element with fixupConfigRules call wrapping the extended plugin', () => {
       const result = generatePluginExtendsElementWithCompatFixup('my-plugin');

packages/eslint/src/generators/utils/flat-config/ast-utils.ts

@@ -315,6 +315,50 @@ export function addImportToFlatConfig(
   ]);
 }
 
+/**
+ * Remove an import from flat config
+ */
+export function removeImportFromFlatConfig(
+  content: string,
+  variable: string,
+  imp: string
+): string {
+  const source = ts.createSourceFile(
+    '',
+    content,
+    ts.ScriptTarget.Latest,
+    true,
+    ts.ScriptKind.JS
+  );
+
+  const changes: StringChange[] = [];
+
+  ts.forEachChild(source, (node) => {
+    // we can only combine object binding patterns
+    if (
+      ts.isVariableStatement(node) &&
+      ts.isVariableDeclaration(node.declarationList.declarations[0]) &&
+      ts.isIdentifier(node.declarationList.declarations[0].name) &&
+      node.declarationList.declarations[0].name.getText() === variable &&
+      ts.isCallExpression(node.declarationList.declarations[0].initializer) &&
+      node.declarationList.declarations[0].initializer.expression.getText() ===
+        'require' &&
+      ts.isStringLiteral(
+        node.declarationList.declarations[0].initializer.arguments[0]
+      ) &&
+      node.declarationList.declarations[0].initializer.arguments[0].text === imp
+    ) {
+      changes.push({
+        type: ChangeType.Delete,
+        start: node.pos,
+        length: node.end - node.pos,
+      });
+    }
+  });
+
+  return applyChangesToString(content, changes);
+}
+
 /**
  * Injects new ts.expression to the end of the module.exports array.
  */
@@ -570,6 +614,52 @@ export function removeCompatExtends(
   return applyChangesToString(content, changes);
 }
 
+export function removePredefinedConfigs(
+  content: string,
+  moduleImport: string,
+  moduleVariable: string,
+  configs: string[]
+): string {
+  const source = ts.createSourceFile(
+    '',
+    content,
+    ts.ScriptTarget.Latest,
+    true,
+    ts.ScriptKind.JS
+  );
+  const changes: StringChange[] = [];
+  let removeImport = true;
+  findAllBlocks(source).forEach((node) => {
+    if (
+      ts.isSpreadElement(node) &&
+      ts.isElementAccessExpression(node.expression) &&
+      ts.isPropertyAccessExpression(node.expression.expression) &&
+      ts.isIdentifier(node.expression.expression.expression) &&
+      node.expression.expression.expression.getText() === moduleVariable &&
+      ts.isStringLiteral(node.expression.argumentExpression)
+    ) {
+      const config = node.expression.argumentExpression.getText();
+      // Check the text without quotes
+      if (configs.includes(config.substring(1, config.length - 1))) {
+        changes.push({
+          type: ChangeType.Delete,
+          start: node.pos,
+          length: node.end - node.pos + 1, // trailing comma
+        });
+      } else {
+        // If there is still a config used, do not remove import
+        removeImport = false;
+      }
+    }
+  });
+
+  let updated = applyChangesToString(content, changes);
+  if (removeImport) {
+    updated = removeImportFromFlatConfig(updated, moduleVariable, moduleImport);
+  }
+  return updated;
+}
+
 /**
  * Add plugins block to the top of the export blocks
  */