Merge pull request #33119 from backstage/freben/cli-common-runcheck-stdio-ignore

Fix runCheck to ignore stdio of spawned process

.changeset/cli-common-runcheck-stdio-ignore.md

@@ -0,0 +1,5 @@
+---
+'@backstage/cli-common': patch
+---
+
+Fixed `runCheck` to ignore stdio of the spawned process, preventing unwanted output from leaking to the terminal.

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

@@ -338,5 +338,26 @@ describe('run', () => {
       const result = await runCheck(['nonexistent-command-12345']);
       expect(result).toBe(false);
     });
+
+    it('should not leak stdout or stderr from the child process', async () => {
+      const stdoutSpy = jest.spyOn(process.stdout, 'write');
+      const stderrSpy = jest.spyOn(process.stderr, 'write');
+      const stdoutBefore = stdoutSpy.mock.calls.length;
+      const stderrBefore = stderrSpy.mock.calls.length;
+
+      await runCheck([
+        'node',
+        '--eval',
+        'console.log("leaked stdout"); console.error("leaked stderr")',
+      ]);
+
+      const stdoutCalls = stdoutSpy.mock.calls.slice(stdoutBefore);
+      const stderrCalls = stderrSpy.mock.calls.slice(stderrBefore);
+      const stdout = stdoutCalls.map(c => String(c[0])).join('');
+      const stderr = stderrCalls.map(c => String(c[0])).join('');
+
+      expect(stdout).not.toContain('leaked stdout');
+      expect(stderr).not.toContain('leaked stderr');
+    });
   });
 });

packages/cli-common/src/run.ts

@@ -211,7 +211,7 @@ export async function runOutput(
  */
 export async function runCheck(args: string[]): Promise<boolean> {
   try {
-    await run(args).waitForExit();
+    await run(args, { stdio: 'ignore' }).waitForExit();
     return true;
   } catch {
     return false;