Improve code coverage

src/main/java/org/example/chaosgame/model/chaos/ChaosGameDescription.java

@@ -90,6 +90,9 @@ public class ChaosGameDescription {
    * @param transforms List of transformations to apply to the points
    */
   private void validateTransforms(List<Transform2D> transforms) {
+    if (transforms == null){
+      throw new IllegalArgumentException("Transformations cannot be null");
+    }
     if (transforms.size() > 4 || transforms.isEmpty()) {
       throw new IllegalArgumentException("Number of transformations must be between 1 and 4");
     }
@@ -112,6 +115,7 @@ public class ChaosGameDescription {
   }
 
   public void setTransforms(List<Transform2D> transforms) {
+    validateTransforms(transforms);
     this.transforms = transforms;
   }
 
@@ -128,7 +132,10 @@ public class ChaosGameDescription {
     if (this == o) return true;
     if (o == null || getClass() != o.getClass()) return false;
     ChaosGameDescription that = (ChaosGameDescription) o;
-    return Objects.equals(minCoords, that.minCoords) && Objects.equals(maxCoords, that.maxCoords) && Objects.equals(transforms, that.transforms) && Objects.equals(probabilities, that.probabilities);
+    return Objects.equals(minCoords, that.minCoords)
+            && Objects.equals(maxCoords, that.maxCoords)
+            && Objects.equals(transforms, that.transforms)
+            && Objects.equals(probabilities, that.probabilities);
   }
 
   @Override

src/test/java/org/example/chaosgame/model/chaos/ChaosGameDescriptionTest.java

@@ -66,27 +66,73 @@ class ChaosGameDescriptionTest {
     assertEquals(probabilities, chaosGameDescription.getProbabilities());
   }
 
-  @Test
-  void testSetTransforms() {
-    Matrix2x2 newMatrix = new Matrix2x2(9.9, 9.9, 9.9, 9.9);
-    Vector2D newVector = new Vector2D(9.9, 9.9);
-    List<Transform2D> newTransforms = Arrays.asList(new AffineTransform2D(newMatrix, newVector));
-    chaosGameDescription.setTransforms(newTransforms);
-    assertEquals(newTransforms, chaosGameDescription.getTransforms());
+  @Nested
+  @DisplayName("SetTransforms")
+  class SetTransforms {
+    @Test
+    @DisplayName("Set null transforms")
+    void testSetNullTransforms() {
+      assertThrows(IllegalArgumentException.class, () -> chaosGameDescription.setTransforms(null));
+    }
+
+    @Test
+    @DisplayName("Set empty transforms")
+    void testSetEmptyTransforms() {
+      assertThrows(IllegalArgumentException.class, () -> chaosGameDescription.setTransforms(List.of()));
+    }
+
+    @Test
+    @DisplayName("Set too many transforms")
+    void testSetTooManyTransforms() {
+      List<Transform2D> tooManyTransforms = Arrays.asList(
+              new AffineTransform2D(matrixA, vectorPartA),
+              new AffineTransform2D(matrixB, vectorPartB),
+              new AffineTransform2D(matrixA, vectorPartA),
+              new AffineTransform2D(matrixB, vectorPartB),
+              new AffineTransform2D(matrixA, vectorPartA)
+      );
+      assertThrows(IllegalArgumentException.class, () -> chaosGameDescription.setTransforms(tooManyTransforms));
+    }
+
+    @Test
+    @DisplayName("Set valid transforms")
+    void testSetValidTransforms() {
+      Matrix2x2 newMatrix = new Matrix2x2(9.9, 9.9, 9.9, 9.9);
+      Vector2D newVector = new Vector2D(9.9, 9.9);
+      List<Transform2D> newTransforms = Arrays.asList(new AffineTransform2D(newMatrix, newVector));
+      chaosGameDescription.setTransforms(newTransforms);
+      assertEquals(newTransforms, chaosGameDescription.getTransforms());
+    }
   }
 
-  @Test
-  void testSetMinCoords() {
-    Vector2D newMinCoords = new Vector2D(-1, -1);
-    chaosGameDescription.setMinCoords(newMinCoords);
-    assertEquals(newMinCoords, chaosGameDescription.getMinCoords());
-  }
-
-  @Test
-  void testSetMaxCoords() {
-    Vector2D newMaxCoords = new Vector2D(2, 2);
-    chaosGameDescription.setMaxCoords(newMaxCoords);
-    assertEquals(newMaxCoords, chaosGameDescription.getMaxCoords());
+  @Nested
+  @DisplayName("Set coordinates")
+  class SetCoordinates {
+    @Test
+    @DisplayName("Set min coordinates")
+    void testSetMinCoords() {
+      Vector2D newMinCoords = new Vector2D(-1, -1);
+      chaosGameDescription.setMinCoords(newMinCoords);
+      assertEquals(newMinCoords, chaosGameDescription.getMinCoords());
+    }
+
+    @Test
+    @DisplayName("Set max coordinates")
+    void testSetMaxCoords() {
+      Vector2D newMaxCoords = new Vector2D(2, 2);
+      chaosGameDescription.setMaxCoords(newMaxCoords);
+      assertEquals(newMaxCoords, chaosGameDescription.getMaxCoords());
+    }
+
+    @Test
+    @DisplayName("Set min and max coordinates")
+    void testSetMinAndMaxCoords() {
+      Vector2D newMinCoords = new Vector2D(-99, -99);
+
+      assertThrows(IllegalArgumentException.class, () -> new ChaosGameDescription(newMinCoords, maxCoords, transforms, probabilities));
+      assertThrows(IllegalArgumentException.class, () -> new ChaosGameDescription(maxCoords, minCoords, transforms, probabilities));
+      assertThrows(IllegalArgumentException.class, () -> new ChaosGameDescription(minCoords, minCoords, transforms, probabilities));
+    }
   }
 
   @Test

src/test/java/org/example/chaosgame/model/chaos/ChaosGameTest.java

@@ -17,8 +17,8 @@ class ChaosGameTest {
   private static ChaosGameDescription affineDescriptionWithProb;
   private static ChaosGame instance;
 
-  @BeforeAll
-  static void setUp() {
+  @BeforeEach
+  void init() {
     juliaDescription = new ChaosGameDescription(
             new Vector2D(-1.6, -1),
             new Vector2D(1.6, 1),
@@ -39,11 +39,8 @@ class ChaosGameTest {
                     new AffineTransform2D(new Matrix2x2(-0.15, 0.28, 0.26, 0.24),
                             new Vector2D(0.0, 0.44))
             ), List.of(2, 84, 7, 7));
-  }
-
-  @BeforeEach
-  void init() {
     instance = ChaosGame.getInstance(juliaDescription, 500, 500);
+    instance.setChaosGameDescription(juliaDescription);
     instance.setSteps(0);
     instance.setTotalSteps(0);
   }
@@ -52,8 +49,6 @@ class ChaosGameTest {
   class SingletonTests {
     @Test
     void testSingletonInstanceIsNull() {
-      instance = null;
-      instance = ChaosGame.getInstance(juliaDescription, 500, 500);
       assertNotNull(instance, "The singleton instance should not be null");
     }
 
@@ -152,6 +147,7 @@ class ChaosGameTest {
     void runStepsWithProbabilities() {
       instance.setChaosGameDescription(affineDescriptionWithProb);
       instance.setSteps(10);
+      instance.runSteps();
       assertEquals(10, instance.getSteps());
     }
   }
@@ -181,4 +177,24 @@ class ChaosGameTest {
     assertEquals(new Vector2D(1.6, 1), instance.getDescription().getMaxCoords(), "The max coords should be the same");
   }
 
+  @Test
+  void registerAndNotifyObservers() {
+    Observer observer = () -> assertTrue(true, "Observer should be notified");
+    instance.registerObserver(observer);
+    instance.notifyObservers();
+  }
+
+  @Test
+  void removeObserver() {
+    Observer observer = () -> fail("Observer should not be notified");
+    instance.registerObserver(observer);
+    instance.removeObserver(observer);
+    instance.notifyObservers();
+  }
+
+  @AfterEach
+  void tearDown() {
+    instance = null;
+  }
+
 }
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