Add extended state variable change into test plan

- Add missing test method for testing variable change events.
- This may also contribute to make tests more reliable when
  testing variable values.
- Should contribute to #76 also.

spring-statemachine-test/src/main/java/org/springframework/statemachine/test/StateMachineTestPlan.java

@@ -101,7 +101,8 @@ public class StateMachineTestPlan<S, E> {
 						step.expectTransitionStarted != null ? step.expectTransitionStarted : 0,
 						step.expectTransitionEnded != null ? step.expectTransitionEnded : 0,
 						step.expectStateMachineStarted != null ? step.expectStateMachineStarted : 0,
-						step.expectStateMachineStopped != null ? step.expectStateMachineStopped : 0);
+						step.expectStateMachineStopped != null ? step.expectStateMachineStopped : 0,
+						step.expectExtendedStateChanged != null ? step.expectExtendedStateChanged : 0);
 			}
 
 			if (step.expectStateMachineStarted != null) {
@@ -212,6 +213,13 @@ public class StateMachineTestPlan<S, E> {
 				}
 			}
 
+			if (step.expectExtendedStateChanged != null) {
+				for (LatchStateMachineListener<S, E> listener : listeners.values()) {
+					assertThat(listener.getExtendedStateChangedLatch().await(defaultAwaitTime, TimeUnit.SECONDS), is(true));
+					assertThat(listener.getExtendedStateChanged().size(), is(step.expectExtendedStateChanged));
+				}
+			}
+
 			if (!step.expectVariableKeys.isEmpty()) {
 				for (StateMachine<S, E> stateMachine : stateMachines.values()) {
 					Map<Object, Object> variables = stateMachine.getExtendedState().getVariables();

spring-statemachine-test/src/main/java/org/springframework/statemachine/test/StateMachineTestPlanBuilder.java

@@ -124,6 +124,7 @@ public class StateMachineTestPlanBuilder<S, E> {
 		Integer expectTransitionEnded;
 		Integer expectStateMachineStarted;
 		Integer expectStateMachineStopped;
+		Integer expectExtendedStateChanged;
 		final Collection<Object> expectVariableKeys = new ArrayList<Object>();
 		final Map<Object, Object> expectVariables = new HashMap<Object, Object>();
 
@@ -381,6 +382,21 @@ public class StateMachineTestPlanBuilder<S, E> {
 			return this;
 		}
 
+		/**
+		 * Expect state machine extended state variables changing {@code count} times.
+		 *
+		 * @param count the count
+		 * @return the state machine test plan step builder
+		 */
+		public StateMachineTestPlanStepBuilder expectExtendedStateChanged(int count) {
+			if (count < 0) {
+				throw new IllegalArgumentException("Expected count cannot be negative, was " + count);
+			}
+			this.expectExtendedStateChanged = count;
+			return this;
+		}
+
+
 		/**
 		 * Add a new step and return {@link StateMachineTestPlanBuilder}
 		 * for chaining.
@@ -391,7 +407,7 @@ public class StateMachineTestPlanBuilder<S, E> {
 			steps.add(new StateMachineTestPlanStep<S, E>(sendEvent, sendMessage, sendEventMachineId, sendEventToAll,
 					expectStates, expectStateChanged, expectStateEntered, expectStateExited, expectEventNotAccepted,
 					expectTransition, expectTransitionStarted, expectTransitionEnded, expectStateMachineStarted,
-					expectStateMachineStopped, expectVariableKeys, expectVariables));
+					expectStateMachineStopped, expectVariableKeys, expectVariables, expectExtendedStateChanged));
 			return StateMachineTestPlanBuilder.this;
 		}
 
@@ -412,6 +428,7 @@ public class StateMachineTestPlanBuilder<S, E> {
 		Integer expectTransitionEnded;
 		Integer expectStateMachineStarted;
 		Integer expectStateMachineStopped;
+		Integer expectExtendedStateChanged;
 		final Collection<Object> expectVariableKeys;
 		final Map<Object, Object> expectVariables;
 
@@ -420,7 +437,7 @@ public class StateMachineTestPlanBuilder<S, E> {
 				Integer expectStateEntered, Integer expectStateExited, Integer expectEventNotAccepted,
 				Integer expectTransition, Integer expectTransitionStarted, Integer expectTransitionEnded,
 				Integer expectStateMachineStarted, Integer expectStateMachineStopped,
-				Collection<Object> expectVariableKeys, Map<Object, Object> expectVariables) {
+				Collection<Object> expectVariableKeys, Map<Object, Object> expectVariables, Integer expectExtendedStateChanged) {
 			this.sendEvent = sendEvent;
 			this.sendMessage = sendMessage;
 			this.sendEventMachineId = sendEventMachineId;
@@ -437,6 +454,7 @@ public class StateMachineTestPlanBuilder<S, E> {
 			this.expectStateMachineStopped = expectStateMachineStopped;
 			this.expectVariableKeys = expectVariableKeys;
 			this.expectVariables = expectVariables;
+			this.expectExtendedStateChanged = expectExtendedStateChanged;
 		}
 
 	}

spring-statemachine-test/src/main/java/org/springframework/statemachine/test/support/LatchStateMachineListener.java

@@ -48,6 +48,7 @@ public class LatchStateMachineListener<S, E> extends StateMachineListenerAdapter
 	private volatile CountDownLatch transitionEndedLatch = new CountDownLatch(1);
 	private volatile CountDownLatch stateMachineStartedLatch = new CountDownLatch(1);
 	private volatile CountDownLatch stateMachineStoppedLatch = new CountDownLatch(1);
+	private volatile CountDownLatch extendedStateChangedLatch = new CountDownLatch(1);
 
 	private final List<StateChangedWrapper<S, E>> stateChanged = new ArrayList<StateChangedWrapper<S, E>>();
 	private final List<State<S, E>> stateEntered = new ArrayList<State<S, E>>();
@@ -58,6 +59,7 @@ public class LatchStateMachineListener<S, E> extends StateMachineListenerAdapter
 	private final List<Transition<S, E>> transitionEnded = new ArrayList<Transition<S, E>>();
 	private final List<StateMachine<S, E>> stateMachineStarted = new ArrayList<StateMachine<S, E>>();
 	private final List<StateMachine<S, E>> stateMachineStopped = new ArrayList<StateMachine<S, E>>();
+	private final List<ExtendedStateChangedWrapper> extendedStateChanged = new ArrayList<ExtendedStateChangedWrapper>();
 
 	@Override
 	public void stateChanged(State<S, E> from, State<S, E> to) {
@@ -131,9 +133,17 @@ public class LatchStateMachineListener<S, E> extends StateMachineListenerAdapter
 		}
 	}
 
+	@Override
+	public void extendedStateChanged(Object key, Object value) {
+		synchronized (lock) {
+			this.extendedStateChanged.add(new ExtendedStateChangedWrapper(key, value));
+			this.extendedStateChangedLatch.countDown();
+		}
+	}
+
 	public void reset(int stateChangedCount, int stateEnteredCount, int stateExitedCount, int eventNotAcceptedCount,
 			int transitionCount, int transitionStartedCount, int transitionEndedCount, int stateMachineStartedCount,
-			int stateMachineStoppedCount) {
+			int stateMachineStoppedCount, int extendedStateChangedCount) {
 		synchronized (lock) {
 			this.stateChangedLatch = new CountDownLatch(stateChangedCount);
 			this.stateEnteredLatch = new CountDownLatch(stateEnteredCount);
@@ -144,6 +154,7 @@ public class LatchStateMachineListener<S, E> extends StateMachineListenerAdapter
 			this.transitionEndedLatch = new CountDownLatch(transitionEndedCount);
 			this.stateMachineStartedLatch = new CountDownLatch(stateMachineStartedCount);
 			this.stateMachineStoppedLatch = new CountDownLatch(stateMachineStoppedCount);
+			this.extendedStateChangedLatch = new CountDownLatch(extendedStateChangedCount);
 			this.stateChanged.clear();
 			this.stateEntered.clear();
 			this.stateExited.clear();
@@ -153,6 +164,7 @@ public class LatchStateMachineListener<S, E> extends StateMachineListenerAdapter
 			this.transitionEnded.clear();
 			this.stateMachineStarted.clear();
 			this.stateMachineStopped.clear();
+			this.extendedStateChanged.clear();
 		}
 	}
 
@@ -192,6 +204,10 @@ public class LatchStateMachineListener<S, E> extends StateMachineListenerAdapter
 		return stateMachineStoppedLatch;
 	}
 
+	public CountDownLatch getExtendedStateChangedLatch() {
+		return extendedStateChangedLatch;
+	}
+
 	public List<StateChangedWrapper<S, E>> getStateChanged() {
 		return stateChanged;
 	}
@@ -228,6 +244,10 @@ public class LatchStateMachineListener<S, E> extends StateMachineListenerAdapter
 		return stateMachineStopped;
 	}
 
+	public List<ExtendedStateChangedWrapper> getExtendedStateChanged() {
+		return extendedStateChanged;
+	}
+
 	public static class StateChangedWrapper<S, E> {
 		final State<S, E> from;
 		final State<S, E> to;
@@ -239,4 +259,15 @@ public class LatchStateMachineListener<S, E> extends StateMachineListenerAdapter
 
 	}
 
+	public static class ExtendedStateChangedWrapper {
+		final Object key;
+		final Object value;
+
+		public ExtendedStateChangedWrapper(Object key, Object value) {
+			this.key = key;
+			this.value = value;
+		}
+
+	}
+
 }

spring-statemachine-zookeeper/src/test/java/org/springframework/statemachine/zookeeper/ZookeeperStateMachineTests.java

@@ -374,6 +374,7 @@ public class ZookeeperStateMachineTests extends AbstractZookeeperTests {
 					.step()
 						.sendEvent(message, machine1)
 						.expectTransition(1)
+						.expectExtendedStateChanged(1)
 						.expectVariable("testVariable", "x1")
 						.and()
 					.build();