Add parameterized ShapeContractTest for Shape interface invariants

Verify clone(), getBounds(), and translate() contracts across all Shape implementations (SRectangle, SCircle, STriangle, SText, SCollection) using @ParameterizedTest + @MethodSource. Also adds junit-jupiter-params dependency to pom.xml. Closes #8
2026-03-27 16:13:59 +01:00
parent c51ae8cfbb
commit 7ddef4d8ab
3 changed files with 105 additions and 0 deletions
--- a/src/test/java/ovh/gasser/newshapes/shapes/ShapeContractTest.java
+++ b/src/test/java/ovh/gasser/newshapes/shapes/ShapeContractTest.java
@@ -0,0 +1,73 @@
+package ovh.gasser.newshapes.shapes;
+
+import org.junit.jupiter.params.ParameterizedTest;
+import org.junit.jupiter.params.provider.MethodSource;
+
+import java.awt.Rectangle;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+/**
+ * Parameterized contract tests verifying Shape interface invariants
+ * across all implementations (SRectangle, SCircle, STriangle, SText, SCollection).
+ */
+class ShapeContractTest {
+
+    @ParameterizedTest(name = "{0}")
+    @MethodSource("ovh.gasser.newshapes.shapes.ShapeFactory#allShapes")
+    void cloneReturnsIndependentCopy(Shape shape) {
+        Shape cloned = shape.clone();
+
+        // clone must not be the same instance
+        assertNotSame(shape, cloned, "clone() must return a new instance");
+
+        // clone must have equal bounds
+        assertEquals(shape.getBounds(), cloned.getBounds(),
+                "clone() must preserve bounds");
+
+        // mutating the clone must not affect the original
+        Rectangle originalBounds = shape.getBounds();
+        cloned.translate(999, 999);
+        assertEquals(originalBounds, shape.getBounds(),
+                "Translating the clone must not affect the original's bounds");
+    }
+
+    @ParameterizedTest(name = "{0}")
+    @MethodSource("ovh.gasser.newshapes.shapes.ShapeFactory#allShapes")
+    void getBoundsReturnsCopy(Shape shape) {
+        Rectangle bounds1 = shape.getBounds();
+        Rectangle bounds2 = shape.getBounds();
+
+        // successive calls must return equal bounds
+        assertEquals(bounds1, bounds2,
+                "getBounds() must return consistent values");
+
+        // but not the same object (defensive copy)
+        assertNotSame(bounds1, bounds2,
+                "getBounds() must return a copy, not internal state");
+
+        // mutating the returned Rectangle must not affect the shape
+        bounds1.translate(500, 500);
+        assertEquals(bounds2, shape.getBounds(),
+                "Mutating the returned Rectangle must not affect the shape");
+    }
+
+    @ParameterizedTest(name = "{0}")
+    @MethodSource("ovh.gasser.newshapes.shapes.ShapeFactory#allShapes")
+    void translateMutatesInPlace(Shape shape) {
+        Rectangle before = shape.getBounds();
+        int dx = 7, dy = -3;
+
+        shape.translate(dx, dy);
+
+        Rectangle after = shape.getBounds();
+        assertEquals(before.x + dx, after.x,
+                "translate() must shift x by dx");
+        assertEquals(before.y + dy, after.y,
+                "translate() must shift y by dy");
+        assertEquals(before.width, after.width,
+                "translate() must not change width");
+        assertEquals(before.height, after.height,
+                "translate() must not change height");
+    }
+}