FSM issue iluwatar#203

Author: Wessam100

FiniteStateMachine/pom.xml

@@ -17,4 +17,46 @@
         <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     </properties>
 
-</project>
+    <dependencies>
+        <!-- Mockito dependency for mocking objects -->
+        <dependency>
+            <groupId>org.mockito</groupId>
+            <artifactId>mockito-core</artifactId>
+            <version>5.5.0</version> <!-- Specify the version for Mockito -->
+            <scope>test</scope>
+        </dependency>
+
+        <!-- JUnit 5 for unit testing -->
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <version>5.8.2</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <version>5.8.2</version>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <build>
+        <plugins>
+            <!-- JaCoCo for code coverage -->
+            <plugin>
+                <groupId>org.jacoco</groupId>
+                <artifactId>jacoco-maven-plugin</artifactId>
+                <version>0.8.7</version>
+                <executions>
+                    <execution>
+                        <goals>
+                            <goal>prepare-agent</goal>
+                            <goal>report</goal>
+                        </goals>
+                    </execution>
+                </executions>
+            </plugin>
+        </plugins>
+    </build>
+</project>

FiniteStateMachine/src/main/java/com/iluwatar/TrafficLightFsm.java

@@ -5,6 +5,7 @@
  * implementation using a traffic light system.
  */
 public class TrafficLightFsm {
+
   /**
    * State interface for traffic light states.
    */
@@ -75,6 +76,14 @@ public void setState(TrafficLightState newState) {
     public void handleEvent() {
       currentState.handleEvent(this);
     }
+
+    /**
+     * Gets the current state of the traffic light.
+     * This can be useful for testing purposes.
+     */
+    public TrafficLightState getCurrentState() {
+      return currentState;
+    }
   }
 
   /**
@@ -94,3 +103,4 @@ public static void main(String[] args) {
 }
 
 
+

FiniteStateMachine/src/main/java/com/iluwatar/TrafficLightFsmTest.java

@@ -0,0 +1,70 @@
+package com.iluwatar;
+
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+
+import static org.mockito.Mockito.*;
+
+class TrafficLightFsmTest {
+
+  private TrafficLightContext context;
+  private TrafficLightState redState;
+  private TrafficLightState greenState;
+  private TrafficLightState yellowState;
+
+  @BeforeEach
+  void setUp() {
+    // Set up the initial states for testing
+    redState = mock(RedLightState.class);
+    greenState = mock(GreenLightState.class);
+    yellowState = mock(YellowLightState.class);
+
+    // Initialize the context with the Red state
+    context = new TrafficLightContext(redState);
+  }
+
+  @Test
+  void testRedToGreenStateTransition() {
+    // Mock the behavior of handleEvent for red state
+    context.handleEvent();  // Expected transition to green state
+    verify(redState).handleEvent(context); // Verify that handleEvent was called
+    assert context.getCurrentState() instanceof GreenLightState; // Assert the next state is Green
+  }
+
+  @Test
+  void testGreenToYellowStateTransition() {
+    // Change to green state manually
+    context.setState(greenState);
+    context.handleEvent();  // Expected transition to yellow state
+    verify(greenState).handleEvent(context); // Verify the handleEvent for green state
+    assert context.getCurrentState() instanceof YellowLightState; // Assert the next state is Yellow
+  }
+
+  @Test
+  void testYellowToRedStateTransition() {
+    // Change to yellow state manually
+    context.setState(yellowState);
+    context.handleEvent();  // Expected transition to red state
+    verify(yellowState).handleEvent(context); // Verify the handleEvent for yellow state
+    assert context.getCurrentState() instanceof RedLightState; // Assert the next state is Red
+  }
+
+  @Test
+  void testStateTransitionOrder() {
+    // Test the full cycle: Red -> Green -> Yellow -> Red
+    context = new TrafficLightContext(new RedLightState());
+
+    // Red to Green
+    context.handleEvent();
+    assert context.getCurrentState() instanceof GreenLightState;
+
+    // Green to Yellow
+    context.handleEvent();
+    assert context.getCurrentState() instanceof YellowLightState;
+
+    // Yellow to Red
+    context.handleEvent();
+    assert context.getCurrentState() instanceof RedLightState;
+  }
+}
+