Fix rq info not found workers information error, Fixes #1139 (#1149)

* Fix rq info not found workers information error, Fixes #1139

* Add test(#1149)

rq/cli/helpers.py

@@ -118,8 +118,12 @@ def show_queues(queues, raw, by_queue, queue_class, worker_class):
 
 def show_workers(queues, raw, by_queue, queue_class, worker_class):
     workers = set()
-    for queue in queues:
-        for worker in worker_class.all(queue=queue):
+    if queues:
+        for queue in queues:
+            for worker in worker_class.all(queue=queue):
+                workers.add(worker)
+    else:
+        for worker in worker_class.all():
             workers.add(worker)
 
     if not by_queue:

tests/test_cli.py

@@ -189,6 +189,13 @@ class TestRQCli(RQTestCase):
         self.assert_normal_execution(result)
         self.assertIn('0 workers, 0 queue', result.output)
 
+        worker = Worker(['default'], connection=self.connection)
+        worker.register_birth()
+        result = runner.invoke(main, ['info', '-u', self.redis_url, '--only-workers'])
+        self.assert_normal_execution(result)
+        self.assertIn('1 workers, 0 queues', result.output)
+        worker.register_death()
+
         queue = Queue(connection=self.connection)
         queue.enqueue(say_hello)
         result = runner.invoke(main, ['info', '-u', self.redis_url, '--only-workers'])
@@ -201,8 +208,8 @@ class TestRQCli(RQTestCase):
         bar_queue = Queue(name='bar', connection=self.connection)
         bar_queue.enqueue(say_hello)
 
-        worker = Worker([foo_queue, bar_queue], connection=self.connection)
-        worker.register_birth()
+        worker_1 = Worker([foo_queue, bar_queue], connection=self.connection)
+        worker_1.register_birth()
 
         worker_2 = Worker([foo_queue, bar_queue], connection=self.connection)
         worker_2.register_birth()