fix(linter): ensure that @nx/eslint-plugin is installed when we add an extracted base eslintrc file (#26679)

The current eslint logic doesn't add the necessary `@nx/eslint-plugin`
package when we extract root config. This PR fixes the issue. This
applies to projects not generated using CNW but rather using something
like `npm create vite`, where the eslint setup isn't what we expect.

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## Current Behavior
<!-- This is the behavior we have today -->

## Expected Behavior
<!-- This is the behavior we should expect with the changes in this PR
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## Related Issue(s)
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Fixes #

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

@@ -1,5 +1,6 @@
 import {
   addDependenciesToPackageJson,
+  GeneratorCallback,
   joinPathFragments,
   offsetFromRoot,
   ProjectConfiguration,
@@ -15,7 +16,7 @@ import {
   getGlobalFlatEslintConfiguration,
 } from './global-eslint-config';
 import { useFlatConfig } from '../../utils/flat-config';
-import { eslintVersion } from '../../utils/versions';
+import { eslintVersion, nxVersion } from '../../utils/versions';
 import {
   addBlockToFlatConfigExport,
   addImportToFlatConfig,
@@ -31,7 +32,7 @@ export function migrateConfigToMonorepoStyle(
   tree: Tree,
   unitTestRunner: string,
   keepExistingVersions?: boolean
-): void {
+): GeneratorCallback {
   const rootEslintConfig = findEslintFile(tree);
   let skipCleanup = false;
   if (
@@ -105,6 +106,14 @@ export function migrateConfigToMonorepoStyle(
       }
     }
   });
+
+  return addDependenciesToPackageJson(
+    tree,
+    {},
+    {
+      '@nx/eslint-plugin': nxVersion,
+    }
+  );
 }
 
 export function findLintTarget(

packages/eslint/src/generators/lint-project/lint-project-convert-monorepo.spec.ts

@@ -0,0 +1,92 @@
+import {
+  addProjectConfiguration,
+  ProjectGraph,
+  readJson,
+  Tree,
+} from '@nx/devkit';
+
+import { Linter } from '../utils/linter';
+import { createTreeWithEmptyWorkspace } from '@nx/devkit/testing';
+import { lintProjectGenerator } from './lint-project';
+
+let projectGraph: ProjectGraph;
+
+jest.mock('@nx/devkit', () => ({
+  ...jest.requireActual<any>('@nx/devkit'),
+  createProjectGraphAsync: jest
+    .fn()
+    .mockImplementation(async () => projectGraph),
+}));
+
+describe('@nx/eslint:lint-project (convert to monorepo style)', () => {
+  let tree: Tree;
+
+  const defaultOptions = {
+    skipFormat: false,
+    addPlugin: true,
+  };
+
+  beforeEach(() => {
+    tree = createTreeWithEmptyWorkspace();
+    const rootpkg = {
+      root: '.',
+      projectType: 'library' as const,
+      targets: {
+        'eslint:lint': {
+          executor: 'nx:run-commands',
+          options: {
+            command: 'eslint .',
+          },
+        },
+      },
+    };
+    projectGraph = {
+      nodes: {
+        rootpkg: {
+          type: 'lib',
+          name: 'rootpkg',
+          data: rootpkg,
+        },
+      },
+      dependencies: {},
+    };
+    addProjectConfiguration(tree, 'rootpkg', rootpkg);
+    tree.write(
+      '.eslintrc.cjs',
+      `
+      module.exports = {
+      root: true,
+      env: { browser: true, es2020: true },
+      extends: [
+        'eslint:recommended',
+        'plugin:@typescript-eslint/recommended',
+        'plugin:react-hooks/recommended',
+      ],
+      ignorePatterns: ['dist', '.eslintrc.cjs'],
+      parser: '@typescript-eslint/parser',
+    }
+    `
+    );
+  });
+
+  it('should generate a eslint config and configure the target in project configuration', async () => {
+    addProjectConfiguration(tree, 'nestedpkg', {
+      root: 'nestedpkg',
+      projectType: 'library',
+      targets: {},
+    });
+
+    await lintProjectGenerator(tree, {
+      ...defaultOptions,
+      linter: Linter.EsLint,
+      project: 'nestedpkg',
+      setParserOptionsProject: false,
+    });
+
+    expect(readJson(tree, 'package.json')).toMatchObject({
+      devDependencies: {
+        '@nx/eslint-plugin': expect.any(String),
+      },
+    });
+  });
+});

packages/eslint/src/generators/lint-project/lint-project.ts

@@ -1,16 +1,16 @@
 import {
   createProjectGraphAsync,
+  formatFiles,
   GeneratorCallback,
   NxJsonConfiguration,
+  offsetFromRoot,
   ProjectConfiguration,
   ProjectGraph,
-  Tree,
-  readNxJson,
-  formatFiles,
-  offsetFromRoot,
   readJson,
+  readNxJson,
   readProjectConfiguration,
   runTasksInSerial,
+  Tree,
   updateJson,
   updateProjectConfiguration,
   writeJson,
@@ -21,10 +21,7 @@ import { findEslintFile } from '../utils/eslint-file';
 import { join } from 'path';
 import { lintInitGenerator } from '../init/init';
 import type { Linter } from 'eslint';
-import {
-  findLintTarget,
-  migrateConfigToMonorepoStyle,
-} from '../init/init-migration';
+import { migrateConfigToMonorepoStyle } from '../init/init-migration';
 import { getProjects } from 'nx/src/generators/utils/project-configuration';
 import { useFlatConfig } from '../../utils/flat-config';
 import {
@@ -36,7 +33,6 @@ import {
 import {
   baseEsLintConfigFile,
   baseEsLintFlatConfigFile,
-  ESLINT_CONFIG_FILENAMES,
 } from '../../utils/config-file';
 import { hasEslintPlugin } from '../utils/plugin';
 import { setupRootEsLint } from './setup-root-eslint';
@@ -144,12 +140,13 @@ export async function lintProjectGeneratorInternal(
           filteredProjects.push(project);
         }
       });
-      migrateConfigToMonorepoStyle(
+      const migrateTask = migrateConfigToMonorepoStyle(
         filteredProjects,
         tree,
         options.unitTestRunner,
         options.keepExistingVersions
       );
+      tasks.push(migrateTask);
     }
   }