eslint-plugin: added tests for no-relative-monorepo-imports

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

packages/eslint-plugin/src/__fixtures__/monorepo/package.json

@@ -0,0 +1,6 @@
+{
+  "name": "root",
+  "workspaces": [
+    "packages/*"
+  ]
+}

packages/eslint-plugin/src/__fixtures__/monorepo/packages/bar/package.json

@@ -0,0 +1,9 @@
+{
+  "name": "@internal/bar",
+  "backstage": {
+    "role": "frontend-plugin"
+  },
+  "peerDependencies": {
+    "react": "*"
+  }
+}

packages/eslint-plugin/src/__fixtures__/monorepo/packages/foo/package.json

@@ -0,0 +1,7 @@
+{
+  "name": "@internal/foo",
+  "dependencies": {
+    "@internal/bar": "1.0.0",
+    "lodash": "*"
+  }
+}

packages/eslint-plugin/src/no-relative-monorepo-imports.test.ts

@@ -0,0 +1,68 @@
+/*
+ * Copyright 2023 The Backstage Authors
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+import { RuleTester } from 'eslint';
+import path from 'path';
+import rule from '../rules/no-relative-monorepo-imports';
+
+const RULE = 'no-relative-monorepo-imports';
+const FIXTURE = path.resolve(__dirname, '__fixtures__/monorepo');
+
+const ERR_OUTSIDE = (path: string) => ({
+  message: `Import of ${path} is outside of any known monorepo package`,
+});
+const ERR_FORBIDDEN = (newImp: string) => ({
+  message: `Relative imports of monorepo packages are forbidden, use '${newImp}' instead`,
+});
+
+process.chdir(FIXTURE);
+
+const ruleTester = new RuleTester({
+  parserOptions: {
+    sourceType: 'module',
+    ecmaVersion: 2021,
+  },
+});
+
+ruleTester.run(RULE, rule, {
+  valid: [
+    {
+      code: `import { version } from '@internal/foo'`,
+      filename: path.join(FIXTURE, 'packages/bar/src/index.ts'),
+    },
+    {
+      code: `import { version } from '@internal/foo/src'`,
+      filename: path.join(FIXTURE, 'packages/bar/src/index.ts'),
+    },
+  ],
+  invalid: [
+    {
+      code: `import { version } from '../../foo'`,
+      filename: path.join(FIXTURE, 'packages/bar/src/index.ts'),
+      errors: [ERR_FORBIDDEN('@internal/foo')],
+    },
+    {
+      code: `import { version } from '../../foo/src'`,
+      filename: path.join(FIXTURE, 'packages/bar/src/index.ts'),
+      errors: [ERR_FORBIDDEN('@internal/foo/src')],
+    },
+    {
+      code: `import { version } from '../../../package.json'`,
+      filename: path.join(FIXTURE, 'packages/bar/src/index.ts'),
+      errors: [ERR_OUTSIDE(path.join(FIXTURE, 'package.json'))],
+    },
+  ],
+});