cli-common: Remove unused findOwnDir and validate findOwnRootDir

Addresses review feedback from PR #32939:
- Remove the `findOwnDir` function which is no longer needed
- Add validation to `findOwnRootDir` to verify the resolved path
  actually contains a monorepo root with a `package.json` that has
  a `workspaces` field

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

.changeset/clean-up-own-root-dir.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli-common': patch
+---
+
+The `findOwnRootDir` utility now searches for the monorepo root by traversing up the directory tree looking for a `package.json` with `workspaces`, instead of assuming a fixed `../..` relative path.

packages/cli-common/src/paths.test.ts

@@ -16,18 +16,18 @@
 
 /* eslint-disable no-restricted-syntax */
 import { resolve as resolvePath } from 'node:path';
-import { findPaths, findRootPath, findOwnDir, findOwnRootDir } from './paths';
+import { findPaths, findRootPath, findOwnRootDir, findOwnPaths } from './paths';
 
 describe('paths', () => {
   afterEach(() => {
     jest.restoreAllMocks();
   });
 
-  it('findOwnDir and findOwnRootDir should find owns paths', () => {
-    const dir = findOwnDir(__dirname);
-    const root = findOwnRootDir(dir);
+  it('findOwnPaths and findOwnRootDir should find own paths', () => {
+    const own = findOwnPaths(__dirname);
+    const root = findOwnRootDir(own.dir);
 
-    expect(dir).toBe(resolvePath(__dirname, '..'));
+    expect(own.dir).toBe(resolvePath(__dirname, '..'));
     expect(root).toBe(resolvePath(__dirname, '../../..'));
   });
 

packages/cli-common/src/paths.ts

@@ -119,7 +119,23 @@ export function findOwnRootDir(ownDir: string) {
     );
   }
 
-  return resolvePath(ownDir, '../..');
+  const rootDir = findRootPath(ownDir, pkgJsonPath => {
+    try {
+      const content = fs.readFileSync(pkgJsonPath, 'utf8');
+      const data = JSON.parse(content);
+      return Boolean(data.workspaces);
+    } catch (error) {
+      throw new Error(
+        `Failed to read package.json at '${pkgJsonPath}', ${error}`,
+      );
+    }
+  });
+
+  if (!rootDir) {
+    throw new Error(`No monorepo root found when searching from '${ownDir}'`);
+  }
+
+  return rootDir;
 }
 
 // Hierarchical directory cache shared across all OwnPathsImpl instances.
@@ -199,11 +215,6 @@ class OwnPathsImpl implements OwnPaths {
   };
 }
 
-// Finds the root of a given package
-export function findOwnDir(searchDir: string) {
-  return OwnPathsImpl.findDir(searchDir);
-}
-
 // Used by the test utility in testUtils.ts to override targetPaths
 export let targetPathsOverride: TargetPaths | undefined;