Add new tests to Dag (#1763)

Test that killing a dag in certain state such as killing won't have
any effect.

With this change, the DAG class has 100% code coverage.

Also make ImmutableSet in the Status enum more strongly typed.

azkaban-exec-server/src/main/java/azkaban/dag/Status.java

@@ -32,22 +32,24 @@ enum Status {
   KILLED; // explicitly killed by a user
 
   // The states that will not transition to other states
-  private static final ImmutableSet TERMINAL_STATES = ImmutableSet.of(DISABLED, SUCCESS, FAILURE,
+  static final ImmutableSet<Status> TERMINAL_STATES = ImmutableSet.of(DISABLED, SUCCESS, FAILURE,
       CANCELED, KILLED);
 
   boolean isTerminal() {
     return TERMINAL_STATES.contains(this);
   }
 
   // The states that are considered as success effectively
-  private static final ImmutableSet EFFECTIVE_SUCCESS_STATES = ImmutableSet.of(DISABLED, SUCCESS);
+  private static final ImmutableSet<Status> EFFECTIVE_SUCCESS_STATES = ImmutableSet.of(DISABLED,
+      SUCCESS);
 
   boolean isSuccessEffectively() {
     return EFFECTIVE_SUCCESS_STATES.contains(this);
   }
 
   // The states that are possible before a node ever starts to run or be killed or canceled
-  private static final ImmutableSet PRE_RUN_STATES = ImmutableSet.of(DISABLED, READY, BLOCKED);
+  private static final ImmutableSet<Status> PRE_RUN_STATES = ImmutableSet
+      .of(DISABLED, READY, BLOCKED);
 
   boolean isPreRunState() {
     return PRE_RUN_STATES.contains(this);

azkaban-exec-server/src/test/java/azkaban/dag/DagTest.java

@@ -17,7 +17,10 @@
 package azkaban.dag;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.any;
 import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.never;
+import static org.mockito.Mockito.verify;
 
 import org.junit.Test;
 
@@ -28,7 +31,8 @@
  */
 public class DagTest {
 
-  private final Dag testFlow = new Dag("fa", mock(DagProcessor.class));
+  private final DagProcessor mockDagProcessor = mock(DagProcessor.class);
+  private final Dag testFlow = new Dag("fa", this.mockDagProcessor);
 
   @Test
   public void dag_finish_with_only_disabled_nodes() {
@@ -49,6 +53,30 @@ public void running_nodes_can_be_killed() {
     assertThat(this.testFlow.getStatus()).isEqualTo(Status.KILLING);
   }
 
+  @Test
+  public void kill_node_in_terminal_state_should_have_no_effect() {
+    for (final Status status : Status.TERMINAL_STATES) {
+      kill_dag_in_this_state_should_have_no_effect(status);
+    }
+  }
+
+  @Test
+  public void kill_node_in_killing_state_should_have_no_effect() {
+    kill_dag_in_this_state_should_have_no_effect(Status.KILLING);
+  }
+
+  private void kill_dag_in_this_state_should_have_no_effect(final Status status) {
+    // given
+    this.testFlow.setStatus(status);
+
+    // when
+    this.testFlow.kill();
+
+    // then
+    assertThat(this.testFlow.getStatus()).isEqualTo(status);
+    verify(this.mockDagProcessor, never()).changeStatus(any(), any());
+  }
+
   /**
    * Tests ready nodes are canceled when the dag is killed.
    */