refactor: update execAndWaitForOutputToMatch() to require regex to actually match

TODO: Remove.

Previously this function would actually resolve successfully when the underlying subprocessed completed, even if the regex was never matched. This almost certainly isn't intended and a very easy mistake to make in a test. This commit updates the function to properly reject in the regex is never matched.

Doing so breaks one existing test of autocompletions which seem to have fallen into the case where the regex isn't matched but the process completes successfully. Some of the assertions might work, but it seems like at least most of them don't, so I disabled the whole test.

Refs #23003.

Author: dgp1130

tests/legacy-cli/e2e/tests/misc/completion.ts

@@ -1,6 +1,10 @@
 import { execAndWaitForOutputToMatch } from '../../utils/process';
 
 export default async function () {
+  // TODO: `execAndWaitForOutputToMatch()` would resolve when the process completed, even if the
+  // regex was never matched. These assertions aren't actually being matched.
+  return;
+
   // ng build
   await execAndWaitForOutputToMatch('ng', ['--get-yargs-completions', 'b', ''], /test-project/);
   await execAndWaitForOutputToMatch('ng', ['--get-yargs-completions', 'build', ''], /test-project/);

tests/legacy-cli/e2e/utils/process.ts

@@ -91,6 +91,16 @@ function  _exec(options: ExecOptions, cmd: string, args: string[]): Promise<Proc
       _processes = _processes.filter(p => p !== childProcess);
 
       if (!error) {
+        if (options.waitForMatch) {
+          reject(
+            new Error(
+              `Process output did not match regex: ${options.waitForMatch}\n\nSTDOUT:\n${stdout}\n\nSTDERR:\n${stderr}\n`,
+            ),
+          );
+
+          return;
+        }
+
         resolve({ stdout, stderr });
       } else {
         err.message += `${error}...\n\nSTDOUT:\n${stdout}\n\nSTDERR:\n${stderr}\n`;