Fix wrongly suggested module paths for @kbn/eslint/module_migration rule (#117781) (#118892)

* Use an alternative KIBANA_ROOT if bazel cache detected

* Use several fallbacks to find the kibana root

* Update comments

* Add test for relative import conversion

* Improve comments

* remove console log

* Improve comments

* Add second case

* improve tests filenames

Co-authored-by: Esteban Beltran <academo@users.noreply.github.com>

packages/kbn-eslint-plugin-eslint/helpers/find_kibana_root.js

@@ -0,0 +1,49 @@
+/*
+ * Copyright Elasticsearch B.V. and/or licensed to Elasticsearch B.V. under one
+ * or more contributor license agreements. Licensed under the Elastic License
+ * 2.0 and the Server Side Public License, v 1; you may not use this file except
+ * in compliance with, at your election, the Elastic License 2.0 or the Server
+ * Side Public License, v 1.
+ */
+
+const path = require('path');
+const fs = require('fs');
+
+function isKibanaRoot(maybeKibanaRoot) {
+  try {
+    const packageJsonPath = path.join(maybeKibanaRoot, 'package.json');
+    fs.accessSync(packageJsonPath, fs.constants.R_OK);
+    const packageJsonContent = fs.readFileSync(packageJsonPath);
+    return JSON.parse(packageJsonContent).name === 'kibana';
+  } catch (e) {
+    return false;
+  }
+}
+
+module.exports = function findKibanaRoot() {
+  let maybeKibanaRoot = path.resolve(__dirname, '../../..');
+
+  // when using syslinks, __dirname reports outside of the repo
+  // if that's the case, the path will contain .cache/bazel
+  if (!maybeKibanaRoot.includes('.cache/bazel')) {
+    return maybeKibanaRoot;
+  }
+
+  // process.argv[1] would be the eslint binary, a correctly-set editor
+  // will use a local eslint inside the repo node_modules and its value
+  // should be `ACTUAL_KIBANA_ROOT/node_modules/.bin/eslint`
+  maybeKibanaRoot = path.resolve(process.argv[1], '../../../');
+  if (isKibanaRoot(maybeKibanaRoot)) {
+    return maybeKibanaRoot;
+  }
+
+  // eslint should run on the repo root level
+  // try to use process.cwd as the kibana root
+  maybeKibanaRoot = process.cwd();
+  if (isKibanaRoot(maybeKibanaRoot)) {
+    return maybeKibanaRoot;
+  }
+
+  // fallback to the first predicted path (original script)
+  return maybeKibanaRoot;
+};

packages/kbn-eslint-plugin-eslint/rules/module_migration.js

@@ -7,7 +7,8 @@
  */
 
 const path = require('path');
-const KIBANA_ROOT = path.resolve(__dirname, '../../..');
+const findKibanaRoot = require('../helpers/find_kibana_root');
+const KIBANA_ROOT = findKibanaRoot();
 
 function checkModuleNameNode(context, mappings, node, desc = 'Imported') {
   const mapping = mappings.find(

packages/kbn-eslint-plugin-eslint/rules/module_migration.test.js

@@ -77,5 +77,76 @@ ruleTester.run('@kbn/eslint/module-migration', rule, {
         export const foo2 = 'bar'
       `,
     },
+    /**
+     * Given this tree:
+     * x-pack/
+     *  - common/
+     *    - foo.ts <-- the target import
+     *    - other/
+     *      - folder/
+     *        - bar.ts <-- the linted fle
+     * import "x-pack/common/foo" should be
+     * import ../../foo
+     */
+    {
+      code: dedent`
+        import "x-pack/common/foo"
+      `,
+      filename: 'x-pack/common/other/folder/bar.ts',
+      options: [
+        [
+          {
+            from: 'x-pack',
+            to: 'foo',
+            toRelative: 'x-pack',
+          },
+        ],
+      ],
+      errors: [
+        {
+          line: 1,
+          message: 'Imported module "x-pack/common/foo" should be "../../foo"',
+        },
+      ],
+      output: dedent`
+        import '../../foo'
+      `,
+    },
+    /**
+     * Given this tree:
+     * x-pack/
+     *  - common/
+     *    - foo.ts <-- the target import
+     *  - another/
+     *     - posible
+     *        - example <-- the linted file
+     *
+     * import "x-pack/common/foo" should be
+     * import ../../common/foo
+     */
+    {
+      code: dedent`
+        import "x-pack/common/foo"
+      `,
+      filename: 'x-pack/another/possible/example.ts',
+      options: [
+        [
+          {
+            from: 'x-pack',
+            to: 'foo',
+            toRelative: 'x-pack',
+          },
+        ],
+      ],
+      errors: [
+        {
+          line: 1,
+          message: 'Imported module "x-pack/common/foo" should be "../../common/foo"',
+        },
+      ],
+      output: dedent`
+        import '../../common/foo'
+      `,
+    },
   ],
 });