Added concept of 'Backout' in workflow steps

- A workflow step can define a 'backout'; i.e. a step to call if
   something goes wrong. This is important for steps that are dealing with
   an open connection as any open connections must be closed.

src/main/java/io/linuxserver/davos/schedule/workflow/FilterFilesWorkflowStep.java

@@ -19,7 +19,9 @@ public class FilterFilesWorkflowStep extends WorkflowStep {
     private static final Logger LOGGER = LoggerFactory.getLogger(FilterFilesWorkflowStep.class);
 
     public FilterFilesWorkflowStep() {
+        
         this.nextStep = new DownloadFilesWorkflowStep();
+        this.backoutStep = new DisconnectWorkflowStep();
     }
 
     @Override
@@ -54,6 +56,9 @@ public class FilterFilesWorkflowStep extends WorkflowStep {
 
             LOGGER.error("Unable to filter files. Error message was: {}", e.getMessage());
             LOGGER.debug("Stacktrace", e);
+            
+            LOGGER.info("Backing out of this run.");
+            backoutStep.runStep(schedule);
         }
     }
 

src/main/java/io/linuxserver/davos/schedule/workflow/WorkflowStep.java

@@ -3,6 +3,7 @@ package io.linuxserver.davos.schedule.workflow;
 public abstract class WorkflowStep {
 
     protected WorkflowStep nextStep;
+    protected WorkflowStep backoutStep;
 
     abstract public void runStep(ScheduleWorkflow schedule);
 }

src/test/java/io/linuxserver/davos/schedule/workflow/ConnectWorkflowStepTest.java

@@ -34,9 +34,12 @@ public class ConnectWorkflowStepTest {
     @Mock
     private Client mockClient;
 
-    @Mock
+    @Mock(name = "nextStep")
     private WorkflowStep mockNextStep;
-
+    
+    @Mock(name = "backoutStep")
+    private WorkflowStep mockBackoutStep;
+    
     @Before
     public void setUp() {
 

src/test/java/io/linuxserver/davos/schedule/workflow/DownloadFilesWorkflowStepTest.java

@@ -32,9 +32,12 @@ public class DownloadFilesWorkflowStepTest {
     @InjectMocks
     private DownloadFilesWorkflowStep workflowStep = new DownloadFilesWorkflowStep();
 
-    @Mock
+    @Mock(name = "nextStep")
     private WorkflowStep mockNextStep;
 
+    @Mock(name = "backoutStep")
+    private WorkflowStep mockBackoutStep;
+    
     @Mock
     private Connection mockConnection;
 

src/test/java/io/linuxserver/davos/schedule/workflow/FilterFilesWorkflowStepTest.java

@@ -27,8 +27,11 @@ public class FilterFilesWorkflowStepTest {
     @InjectMocks
     private FilterFilesWorkflowStep workflowStep = new FilterFilesWorkflowStep();
 
-    @Mock
+    @Mock(name = "nextStep")
     private DownloadFilesWorkflowStep mockNextStep;
+    
+    @Mock(name = "backoutStep")
+    private DisconnectWorkflowStep mockBackupStep;
 
     @Mock
     private Connection mockConnection;
@@ -207,7 +210,7 @@ public class FilterFilesWorkflowStepTest {
     }
 
     @Test
-    public void ifListingFilesIsUnsuccessfulThenDoNotCallNextStep() {
+    public void ifListingFilesIsUnsuccessfulThenDoNotCallNextStepAndCallBackupStepInstead() {
 
         ScheduleConfiguration config = new ScheduleConfiguration(null, null, null, 0, null, "remote/", "local/",
                 FileTransferType.FILES_ONLY);
@@ -220,5 +223,6 @@ public class FilterFilesWorkflowStepTest {
         workflowStep.runStep(schedule);
 
         verify(mockNextStep, never()).runStep(schedule);
+        verify(mockBackupStep).runStep(schedule);
     }
 }