diff --git a/airflow/operators/docker_operator.py b/airflow/operators/docker_operator.py
index 517199be513cb..07ad5f5c74d38 100644
--- a/airflow/operators/docker_operator.py
+++ b/airflow/operators/docker_operator.py
@@ -43,6 +43,7 @@ class DockerOperator(BaseOperator):
     be provided with the parameter ``docker_conn_id``.
 
     :param image: Docker image from which to create the container.
+        If image tag is omitted, "latest" will be used.
     :type image: str
     :param api_version: Remote API version. Set to ``auto`` to automatically
         detect the server's version.
@@ -62,7 +63,7 @@ class DockerOperator(BaseOperator):
     :type docker_url: str
     :param environment: Environment variables to set in the container. (templated)
     :type environment: dict
-    :param force_pull: Pull the docker image on every run. Default is false.
+    :param force_pull: Pull the docker image on every run. Default is False.
     :type force_pull: bool
     :param mem_limit: Maximum amount of memory the container can use.
         Either a float value, which represents the limit in bytes,
@@ -187,35 +188,28 @@ def execute(self, context):
                 tls=tls_config
             )
 
-        if ':' not in self.image:
-            image = self.image + ':latest'
-        else:
-            image = self.image
-
-        if self.force_pull or len(self.cli.images(name=image)) == 0:
-            self.log.info('Pulling docker image %s', image)
-            for l in self.cli.pull(image, stream=True):
+        if self.force_pull or len(self.cli.images(name=self.image)) == 0:
+            self.log.info('Pulling docker image %s', self.image)
+            for l in self.cli.pull(self.image, stream=True):
                 output = json.loads(l.decode('utf-8'))
                 self.log.info("%s", output['status'])
 
-        cpu_shares = int(round(self.cpus * 1024))
-
         with TemporaryDirectory(prefix='airflowtmp') as host_tmp_dir:
             self.environment['AIRFLOW_TMP_DIR'] = self.tmp_dir
             self.volumes.append('{0}:{1}'.format(host_tmp_dir, self.tmp_dir))
 
             self.container = self.cli.create_container(
                 command=self.get_command(),
-                cpu_shares=cpu_shares,
                 environment=self.environment,
                 host_config=self.cli.create_host_config(
                     binds=self.volumes,
                     network_mode=self.network_mode,
                     shm_size=self.shm_size,
                     dns=self.dns,
-                    dns_search=self.dns_search),
-                image=image,
-                mem_limit=self.mem_limit,
+                    dns_search=self.dns_search,
+                    cpu_shares=int(round(self.cpus * 1024)),
+                    mem_limit=self.mem_limit),
+                image=self.image,
                 user=self.user,
                 working_dir=self.working_dir
             )
diff --git a/tests/operators/docker_operator.py b/tests/operators/test_docker_operator.py
similarity index 97%
rename from tests/operators/docker_operator.py
rename to tests/operators/test_docker_operator.py
index ea90c53c28d82..a7d63e4ebcf1d 100644
--- a/tests/operators/docker_operator.py
+++ b/tests/operators/test_docker_operator.py
@@ -64,20 +64,22 @@ def test_execute(self, client_class_mock, mkdtemp_mock):
         client_class_mock.assert_called_with(base_url='unix://var/run/docker.sock', tls=None,
                                              version='1.19')
 
-        client_mock.create_container.assert_called_with(command='env', cpu_shares=1024,
+        client_mock.create_container.assert_called_with(command='env',
                                                         environment={
                                                             'AIRFLOW_TMP_DIR': '/tmp/airflow',
                                                             'UNIT': 'TEST'
                                                         },
                                                         host_config=host_config,
                                                         image='ubuntu:latest',
-                                                        mem_limit=None, user=None,
+                                                        user=None,
                                                         working_dir='/container/path'
                                                         )
         client_mock.create_host_config.assert_called_with(binds=['/host/path:/container/path',
                                                                  '/mkdtemp:/tmp/airflow'],
                                                           network_mode='bridge',
                                                           shm_size=1000,
+                                                          cpu_shares=1024,
+                                                          mem_limit=None,
                                                           dns=None,
                                                           dns_search=None)
         client_mock.images.assert_called_with(name='ubuntu:latest')
diff --git a/tests/operators/hive_operator.py b/tests/operators/test_hive_operator.py
similarity index 100%
rename from tests/operators/hive_operator.py
rename to tests/operators/test_hive_operator.py
diff --git a/tests/operators/latest_only_operator.py b/tests/operators/test_latest_only_operator.py
similarity index 100%
rename from tests/operators/latest_only_operator.py
rename to tests/operators/test_latest_only_operator.py
diff --git a/tests/operators/python_operator.py b/tests/operators/test_python_operator.py
similarity index 100%
rename from tests/operators/python_operator.py
rename to tests/operators/test_python_operator.py
diff --git a/tests/operators/s3_to_hive_operator.py b/tests/operators/test_s3_to_hive_operator.py
similarity index 100%
rename from tests/operators/s3_to_hive_operator.py
rename to tests/operators/test_s3_to_hive_operator.py
diff --git a/tests/operators/slack_operator.py b/tests/operators/test_slack_operator.py
similarity index 100%
rename from tests/operators/slack_operator.py
rename to tests/operators/test_slack_operator.py
diff --git a/tests/operators/subdag_operator.py b/tests/operators/test_subdag_operator.py
similarity index 100%
rename from tests/operators/subdag_operator.py
rename to tests/operators/test_subdag_operator.py