rm-gocheck: fix compile errors from converting check.CommentInterface to string

while :; do \
	out=$(go test -c ./integration-cli 2>&1 | grep 'cannot use nil as type string in return argument') || break
	echo "$out" | while read line; do
		file=$(echo "$line" | cut -d: -f1)
		n=$(echo "$line" | cut -d: -f2)
		sed -E -i "${n}"'s#\b(return .*, )nil#\1""#g' "$file"
	done
done \
&& \
while :; do \
	out=$(go test -c ./integration-cli/daemon 2>&1 | grep 'cannot use nil as type string in return argument') || break
	echo "$out" | while read line; do
		file=$(echo "$line" | cut -d: -f1)
		n=$(echo "$line" | cut -d: -f2)
		sed -E -i "${n}"'s#\b(return .*, )nil#\1""#g' "$file"
	done
done \
&& \
while :; do \
	out=$(go test -c ./pkg/discovery 2>&1 | grep 'cannot use nil as type string in return argument') || break
	echo "$out" | while read line; do
		file=$(echo "$line" | cut -d: -f1)
		n=$(echo "$line" | cut -d: -f2)
		sed -E -i "${n}"'s#\b(return .*, )nil#\1""#g' "$file"
	done
done \
&& \
while :; do \
	out=$(go test -c ./pkg/discovery/file 2>&1 | grep 'cannot use nil as type string in return argument') || break
	echo "$out" | while read line; do
		file=$(echo "$line" | cut -d: -f1)
		n=$(echo "$line" | cut -d: -f2)
		sed -E -i "${n}"'s#\b(return .*, )nil#\1""#g' "$file"
	done
done \
&& \
while :; do \
	out=$(go test -c ./pkg/discovery/kv 2>&1 | grep 'cannot use nil as type string in return argument') || break
	echo "$out" | while read line; do
		file=$(echo "$line" | cut -d: -f1)
		n=$(echo "$line" | cut -d: -f2)
		sed -E -i "${n}"'s#\b(return .*, )nil#\1""#g' "$file"
	done
done \
&& \
while :; do \
	out=$(go test -c ./pkg/discovery/memory 2>&1 | grep 'cannot use nil as type string in return argument') || break
	echo "$out" | while read line; do
		file=$(echo "$line" | cut -d: -f1)
		n=$(echo "$line" | cut -d: -f2)
		sed -E -i "${n}"'s#\b(return .*, )nil#\1""#g' "$file"
	done
done \
&& \
while :; do \
	out=$(go test -c ./pkg/discovery/nodes 2>&1 | grep 'cannot use nil as type string in return argument') || break
	echo "$out" | while read line; do
		file=$(echo "$line" | cut -d: -f1)
		n=$(echo "$line" | cut -d: -f2)
		sed -E -i "${n}"'s#\b(return .*, )nil#\1""#g' "$file"
	done
done

Signed-off-by: Tibor Vass <tibor@docker.com>
(cherry picked from commit 64de5e82289b1a97b3a9757959210a0400a602f7)
Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

integration-cli/daemon/daemon.go

@@ -92,7 +92,7 @@ func (d *Daemon) CheckActiveContainerCount(c *testing.T) (interface{}, string) {
 	out, err := d.Cmd("ps", "-q")
 	assert.NilError(c, err)
 	if len(strings.TrimSpace(out)) == 0 {
-		return 0, nil
+		return 0, ""
 	}
 	return len(strings.Split(strings.TrimSpace(out), "\n")), fmt.Sprintf("output: %q", string(out))
 }

integration-cli/daemon/daemon_swarm.go

@@ -26,7 +26,7 @@ func (d *Daemon) CheckServiceTasksInState(service string, state swarm.TaskState,
 				}
 			}
 		}
-		return count, nil
+		return count, ""
 	}
 }
 
@@ -43,7 +43,7 @@ func (d *Daemon) CheckServiceTasksInStateWithError(service string, state swarm.T
 				}
 			}
 		}
-		return count, nil
+		return count, ""
 	}
 }
 
@@ -57,9 +57,9 @@ func (d *Daemon) CheckServiceUpdateState(service string) func(*testing.T) (inter
 	return func(c *testing.T) (interface{}, string) {
 		service := d.GetService(c, service)
 		if service.UpdateStatus == nil {
-			return "", nil
+			return "", ""
 		}
-		return service.UpdateStatus.State, nil
+		return service.UpdateStatus.State, ""
 	}
 }
 
@@ -93,7 +93,7 @@ func (d *Daemon) CheckPluginImage(plugin string) func(c *testing.T) (interface{}
 func (d *Daemon) CheckServiceTasks(service string) func(*testing.T) (interface{}, string) {
 	return func(c *testing.T) (interface{}, string) {
 		tasks := d.GetServiceTasks(c, service)
-		return len(tasks), nil
+		return len(tasks), ""
 	}
 }
 
@@ -118,7 +118,7 @@ func (d *Daemon) CheckRunningTaskNetworks(c *testing.T) (interface{}, string) {
 			result[network.Target]++
 		}
 	}
-	return result, nil
+	return result, ""
 }
 
 // CheckRunningTaskImages returns the times each image is running as a task.
@@ -142,7 +142,7 @@ func (d *Daemon) CheckRunningTaskImages(c *testing.T) (interface{}, string) {
 			result[task.Spec.ContainerSpec.Image]++
 		}
 	}
-	return result, nil
+	return result, ""
 }
 
 // CheckNodeReadyCount returns the number of ready node on the swarm
@@ -154,20 +154,20 @@ func (d *Daemon) CheckNodeReadyCount(c *testing.T) (interface{}, string) {
 			readyCount++
 		}
 	}
-	return readyCount, nil
+	return readyCount, ""
 }
 
 // CheckLocalNodeState returns the current swarm node state
 func (d *Daemon) CheckLocalNodeState(c *testing.T) (interface{}, string) {
 	info := d.SwarmInfo(c)
-	return info.LocalNodeState, nil
+	return info.LocalNodeState, ""
 }
 
 // CheckControlAvailable returns the current swarm control available
 func (d *Daemon) CheckControlAvailable(c *testing.T) (interface{}, string) {
 	info := d.SwarmInfo(c)
 	assert.Equal(c, info.LocalNodeState, swarm.LocalNodeStateActive)
-	return info.ControlAvailable, nil
+	return info.ControlAvailable, ""
 }
 
 // CheckLeader returns whether there is a leader on the swarm or not
@@ -184,7 +184,7 @@ func (d *Daemon) CheckLeader(c *testing.T) (interface{}, string) {
 
 	for _, node := range ls {
 		if node.ManagerStatus != nil && node.ManagerStatus.Leader {
-			return nil, nil
+			return nil, ""
 		}
 	}
 	return fmt.Errorf("no leader"), "could not find leader"

integration-cli/docker_api_exec_test.go

@@ -218,7 +218,7 @@ func (s *DockerSuite) TestExecStateCleanup(c *testing.T) {
 	checkReadDir := func(c *testing.T) (interface{}, string) {
 		fi, err := ioutil.ReadDir(stateDir)
 		assert.NilError(c, err)
-		return len(fi), nil
+		return len(fi), ""
 	}
 
 	fi, err := ioutil.ReadDir(stateDir)

integration-cli/docker_api_swarm_service_test.go

@@ -231,7 +231,7 @@ func (s *DockerSwarmSuite) TestAPISwarmServicesUpdateStartFirst(c *testing.T) {
 					startingTasks = append(startingTasks, t)
 				}
 			}
-			return startingTasks, nil
+			return startingTasks, ""
 		}, checker.HasLen, expected)
 
 		return startingTasks

integration-cli/docker_api_swarm_test.go

@@ -229,7 +229,7 @@ func (s *DockerSwarmSuite) TestAPISwarmPromoteDemote(c *testing.T) {
 		}
 		certs, err := helpers.ParseCertificatesPEM(certBytes)
 		if err == nil && len(certs) > 0 && len(certs[0].Subject.OrganizationalUnit) > 0 {
-			return certs[0].Subject.OrganizationalUnit[0], nil
+			return certs[0].Subject.OrganizationalUnit[0], ""
 		}
 		return "", "could not get organizational unit from certificate"
 	}, checker.Equals, "swarm-worker")
@@ -405,7 +405,7 @@ func (s *DockerSwarmSuite) TestAPISwarmRaftQuorum(c *testing.T) {
 	// d1 will eventually step down from leader because there is no longer an active quorum, wait for that to happen
 	waitAndAssert(c, defaultReconciliationTimeout*2, func(c *testing.T) (interface{}, string) {
 		_, err := cli.ServiceCreate(context.Background(), service.Spec, types.ServiceCreateOptions{})
-		return err.Error(), nil
+		return err.Error(), ""
 	}, checker.Contains, "Make sure more than half of the managers are online.")
 
 	d2.StartNode(c)
@@ -756,7 +756,7 @@ func checkClusterHealth(c *testing.T, cl []*daemon.Daemon, managerCount, workerC
 		for _, n := range d.ListNodes(c) {
 			waitReady := func(c *testing.T) (interface{}, string) {
 				if n.Status.State == swarm.NodeStateReady {
-					return true, nil
+					return true, ""
 				}
 				nn := d.GetNode(c, n.ID)
 				n = *nn
@@ -766,7 +766,7 @@ func checkClusterHealth(c *testing.T, cl []*daemon.Daemon, managerCount, workerC
 
 			waitActive := func(c *testing.T) (interface{}, string) {
 				if n.Spec.Availability == swarm.NodeAvailabilityActive {
-					return true, nil
+					return true, ""
 				}
 				nn := d.GetNode(c, n.ID)
 				n = *nn

integration-cli/docker_cli_daemon_test.go

@@ -2073,7 +2073,7 @@ func (s *DockerDaemonSuite) TestDaemonRestartWithUnpausedRunningContainer(t *tes
 	// the resume event might be received after we do the inspect
 	waitAndAssert(t, defaultReconciliationTimeout, func(*testing.T) (interface{}, string) {
 		result := icmd.RunCommand("kill", "-0", strings.TrimSpace(pid))
-		return result.ExitCode, nil
+		return result.ExitCode, ""
 	}, checker.Equals, 0)
 
 	// restart the daemon

integration-cli/docker_cli_prune_unix_test.go

@@ -27,7 +27,7 @@ func pruneNetworkAndVerify(c *testing.T, d *daemon.Daemon, kept, pruned []string
 		waitAndAssert(c, defaultReconciliationTimeout, func(*testing.T) (interface{}, string) {
 			out, err := d.Cmd("network", "ls", "--format", "{{.Name}}")
 			assert.NilError(c, err)
-			return out, nil
+			return out, ""
 		}, checker.Contains, s)
 	}
 
@@ -35,7 +35,7 @@ func pruneNetworkAndVerify(c *testing.T, d *daemon.Daemon, kept, pruned []string
 		waitAndAssert(c, defaultReconciliationTimeout, func(*testing.T) (interface{}, string) {
 			out, err := d.Cmd("network", "ls", "--format", "{{.Name}}")
 			assert.NilError(c, err)
-			return out, nil
+			return out, ""
 		}, checker.Not(checker.Contains), s)
 	}
 }

integration-cli/docker_cli_restart_test.go

@@ -38,7 +38,7 @@ func (s *DockerSuite) TestRestartRunningContainer(c *testing.T) {
 
 	getLogs := func(c *testing.T) (interface{}, string) {
 		out, _ := dockerCmd(c, "logs", cleanedContainerID)
-		return out, nil
+		return out, ""
 	}
 
 	// Wait 10 seconds for the 'echo' to appear in the logs

integration-cli/docker_cli_service_create_test.go

@@ -25,7 +25,7 @@ func (s *DockerSwarmSuite) TestServiceCreateMountVolume(c *testing.T) {
 	var tasks []swarm.Task
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		tasks = d.GetServiceTasks(c, id)
-		return len(tasks) > 0, nil
+		return len(tasks) > 0, ""
 	}, checker.Equals, true)
 
 	task := tasks[0]
@@ -33,7 +33,7 @@ func (s *DockerSwarmSuite) TestServiceCreateMountVolume(c *testing.T) {
 		if task.NodeID == "" || task.Status.ContainerStatus == nil {
 			task = d.GetTask(c, task.ID)
 		}
-		return task.NodeID != "" && task.Status.ContainerStatus != nil, nil
+		return task.NodeID != "" && task.Status.ContainerStatus != nil, ""
 	}, checker.Equals, true)
 
 	// check container mount config
@@ -139,7 +139,7 @@ func (s *DockerSwarmSuite) TestServiceCreateWithSecretSourceTargetPaths(c *testi
 	var tasks []swarm.Task
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		tasks = d.GetServiceTasks(c, serviceName)
-		return len(tasks) > 0, nil
+		return len(tasks) > 0, ""
 	}, checker.Equals, true)
 
 	task := tasks[0]
@@ -147,7 +147,7 @@ func (s *DockerSwarmSuite) TestServiceCreateWithSecretSourceTargetPaths(c *testi
 		if task.NodeID == "" || task.Status.ContainerStatus == nil {
 			task = d.GetTask(c, task.ID)
 		}
-		return task.NodeID != "" && task.Status.ContainerStatus != nil, nil
+		return task.NodeID != "" && task.Status.ContainerStatus != nil, ""
 	}, checker.Equals, true)
 
 	for testName, testTarget := range testPaths {
@@ -189,7 +189,7 @@ func (s *DockerSwarmSuite) TestServiceCreateWithSecretReferencedTwice(c *testing
 	var tasks []swarm.Task
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		tasks = d.GetServiceTasks(c, serviceName)
-		return len(tasks) > 0, nil
+		return len(tasks) > 0, ""
 	}, checker.Equals, true)
 
 	task := tasks[0]
@@ -197,7 +197,7 @@ func (s *DockerSwarmSuite) TestServiceCreateWithSecretReferencedTwice(c *testing
 		if task.NodeID == "" || task.Status.ContainerStatus == nil {
 			task = d.GetTask(c, task.ID)
 		}
-		return task.NodeID != "" && task.Status.ContainerStatus != nil, nil
+		return task.NodeID != "" && task.Status.ContainerStatus != nil, ""
 	}, checker.Equals, true)
 
 	for _, target := range []string{"target1", "target2"} {
@@ -286,7 +286,7 @@ func (s *DockerSwarmSuite) TestServiceCreateWithConfigSourceTargetPaths(c *testi
 	var tasks []swarm.Task
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		tasks = d.GetServiceTasks(c, serviceName)
-		return len(tasks) > 0, nil
+		return len(tasks) > 0, ""
 	}, checker.Equals, true)
 
 	task := tasks[0]
@@ -294,7 +294,7 @@ func (s *DockerSwarmSuite) TestServiceCreateWithConfigSourceTargetPaths(c *testi
 		if task.NodeID == "" || task.Status.ContainerStatus == nil {
 			task = d.GetTask(c, task.ID)
 		}
-		return task.NodeID != "" && task.Status.ContainerStatus != nil, nil
+		return task.NodeID != "" && task.Status.ContainerStatus != nil, ""
 	}, checker.Equals, true)
 
 	for testName, testTarget := range testPaths {
@@ -336,7 +336,7 @@ func (s *DockerSwarmSuite) TestServiceCreateWithConfigReferencedTwice(c *testing
 	var tasks []swarm.Task
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		tasks = d.GetServiceTasks(c, serviceName)
-		return len(tasks) > 0, nil
+		return len(tasks) > 0, ""
 	}, checker.Equals, true)
 
 	task := tasks[0]
@@ -344,7 +344,7 @@ func (s *DockerSwarmSuite) TestServiceCreateWithConfigReferencedTwice(c *testing
 		if task.NodeID == "" || task.Status.ContainerStatus == nil {
 			task = d.GetTask(c, task.ID)
 		}
-		return task.NodeID != "" && task.Status.ContainerStatus != nil, nil
+		return task.NodeID != "" && task.Status.ContainerStatus != nil, ""
 	}, checker.Equals, true)
 
 	for _, target := range []string{"target1", "target2"} {
@@ -368,7 +368,7 @@ func (s *DockerSwarmSuite) TestServiceCreateMountTmpfs(c *testing.T) {
 	var tasks []swarm.Task
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		tasks = d.GetServiceTasks(c, id)
-		return len(tasks) > 0, nil
+		return len(tasks) > 0, ""
 	}, checker.Equals, true)
 
 	task := tasks[0]
@@ -376,7 +376,7 @@ func (s *DockerSwarmSuite) TestServiceCreateMountTmpfs(c *testing.T) {
 		if task.NodeID == "" || task.Status.ContainerStatus == nil {
 			task = d.GetTask(c, task.ID)
 		}
-		return task.NodeID != "" && task.Status.ContainerStatus != nil, nil
+		return task.NodeID != "" && task.Status.ContainerStatus != nil, ""
 	}, checker.Equals, true)
 
 	// check container mount config
@@ -424,7 +424,7 @@ func (s *DockerSwarmSuite) TestServiceCreateWithNetworkAlias(c *testing.T) {
 	var tasks []swarm.Task
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		tasks = d.GetServiceTasks(c, id)
-		return len(tasks) > 0, nil
+		return len(tasks) > 0, ""
 	}, checker.Equals, true)
 
 	task := tasks[0]
@@ -432,7 +432,7 @@ func (s *DockerSwarmSuite) TestServiceCreateWithNetworkAlias(c *testing.T) {
 		if task.NodeID == "" || task.Status.ContainerStatus == nil {
 			task = d.GetTask(c, task.ID)
 		}
-		return task.NodeID != "" && task.Status.ContainerStatus != nil, nil
+		return task.NodeID != "" && task.Status.ContainerStatus != nil, ""
 	}, checker.Equals, true)
 
 	// check container alias config

integration-cli/docker_cli_service_health_test.go

@@ -41,7 +41,7 @@ func (s *DockerSwarmSuite) TestServiceHealthRun(c *testing.T) {
 	var tasks []swarm.Task
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		tasks = d.GetServiceTasks(c, id)
-		return tasks, nil
+		return tasks, ""
 	}, checker.HasLen, 1)
 
 	task := tasks[0]
@@ -49,14 +49,14 @@ func (s *DockerSwarmSuite) TestServiceHealthRun(c *testing.T) {
 	// wait for task to start
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		task = d.GetTask(c, task.ID)
-		return task.Status.State, nil
+		return task.Status.State, ""
 	}, checker.Equals, swarm.TaskStateRunning)
 	containerID := task.Status.ContainerStatus.ContainerID
 
 	// wait for container to be healthy
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		out, _ := d.Cmd("inspect", "--format={{.State.Health.Status}}", containerID)
-		return strings.TrimSpace(out), nil
+		return strings.TrimSpace(out), ""
 	}, checker.Equals, "healthy")
 
 	// make it fail
@@ -64,13 +64,13 @@ func (s *DockerSwarmSuite) TestServiceHealthRun(c *testing.T) {
 	// wait for container to be unhealthy
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		out, _ := d.Cmd("inspect", "--format={{.State.Health.Status}}", containerID)
-		return strings.TrimSpace(out), nil
+		return strings.TrimSpace(out), ""
 	}, checker.Equals, "unhealthy")
 
 	// Task should be terminated
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		task = d.GetTask(c, task.ID)
-		return task.Status.State, nil
+		return task.Status.State, ""
 	}, checker.Equals, swarm.TaskStateFailed)
 
 	if !strings.Contains(task.Status.Err, container.ErrContainerUnhealthy.Error()) {
@@ -102,7 +102,7 @@ func (s *DockerSwarmSuite) TestServiceHealthStart(c *testing.T) {
 	var tasks []swarm.Task
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		tasks = d.GetServiceTasks(c, id)
-		return tasks, nil
+		return tasks, ""
 	}, checker.HasLen, 1)
 
 	task := tasks[0]
@@ -110,7 +110,7 @@ func (s *DockerSwarmSuite) TestServiceHealthStart(c *testing.T) {
 	// wait for task to start
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		task = d.GetTask(c, task.ID)
-		return task.Status.State, nil
+		return task.Status.State, ""
 	}, checker.Equals, swarm.TaskStateStarting)
 
 	containerID := task.Status.ContainerStatus.ContainerID
@@ -119,7 +119,7 @@ func (s *DockerSwarmSuite) TestServiceHealthStart(c *testing.T) {
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		out, _ := d.Cmd("inspect", "--format={{.State.Health.FailingStreak}}", containerID)
 		failingStreak, _ := strconv.Atoi(strings.TrimSpace(out))
-		return failingStreak, nil
+		return failingStreak, ""
 	}, checker.GreaterThan, 0)
 
 	// task should be blocked at starting status
@@ -132,6 +132,6 @@ func (s *DockerSwarmSuite) TestServiceHealthStart(c *testing.T) {
 	// Task should be at running status
 	waitAndAssert(c, defaultReconciliationTimeout, func(c *testing.T) (interface{}, string) {
 		task = d.GetTask(c, task.ID)
-		return task.Status.State, nil
+		return task.Status.State, ""
 	}, checker.Equals, swarm.TaskStateRunning)
 }

integration-cli/docker_cli_swarm_test.go

@@ -385,7 +385,7 @@ func (s *DockerSwarmSuite) TestSwarmContainerAttachByNetworkId(c *testing.T) {
 	checkNetwork := func(*testing.T) (interface{}, string) {
 		out, err := d.Cmd("network", "ls")
 		assert.NilError(c, err)
-		return out, nil
+		return out, ""
 	}
 
 	waitAndAssert(c, 3*time.Second, checkNetwork, checker.Not(checker.Contains), "testnet")
@@ -546,7 +546,7 @@ func (s *DockerSwarmSuite) TestSwarmTaskListFilter(c *testing.T) {
 	checkNumTasks := func(*testing.T) (interface{}, string) {
 		out, err := d.Cmd("service", "ps", "--filter", filter, name)
 		assert.NilError(c, err, out)
-		return len(strings.Split(out, "\n")) - 2, nil // includes header and nl in last line
+		return len(strings.Split(out, "\n")) - 2, "" // includes header and nl in last line
 	}
 
 	// wait until all tasks have been created
@@ -988,15 +988,15 @@ func checkKeyIsEncrypted(d *daemon.Daemon) func(*testing.T) (interface{}, string
 	return func(c *testing.T) (interface{}, string) {
 		keyBytes, err := ioutil.ReadFile(filepath.Join(d.Folder, "root", "swarm", "certificates", "swarm-node.key"))
 		if err != nil {
-			return fmt.Errorf("error reading key: %v", err), nil
+			return fmt.Errorf("error reading key: %v", err), ""
 		}
 
 		keyBlock, _ := pem.Decode(keyBytes)
 		if keyBlock == nil {
-			return fmt.Errorf("invalid PEM-encoded private key"), nil
+			return fmt.Errorf("invalid PEM-encoded private key"), ""
 		}
 
-		return keyutils.IsEncryptedPEMBlock(keyBlock), nil
+		return keyutils.IsEncryptedPEMBlock(keyBlock), ""
 	}
 }
 
@@ -1220,7 +1220,7 @@ func (s *DockerSwarmSuite) TestSwarmJoinPromoteLocked(c *testing.T) {
 		}
 		certs, err := helpers.ParseCertificatesPEM(certBytes)
 		if err == nil && len(certs) > 0 && len(certs[0].Subject.OrganizationalUnit) > 0 {
-			return certs[0].Subject.OrganizationalUnit[0], nil
+			return certs[0].Subject.OrganizationalUnit[0], ""
 		}
 		return "", "could not get organizational unit from certificate"
 	}, checker.Equals, "swarm-worker")