test: add ColorAttributes unit tests

Add 16 tests covering constructor behavior, fill/stroke flags and colors,
null color handling, ID constant, Attributes interface, toString output,
and instance independence.

Closes #7

src/test/java/ovh/gasser/newshapes/attributes/ColorAttributesTest.java

@@ -0,0 +1,129 @@
+package ovh.gasser.newshapes.attributes;
+
+import org.junit.jupiter.api.Test;
+
+import java.awt.*;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class ColorAttributesTest {
+
+    @Test
+    void testConstructorStoresFilledFlag() {
+        ColorAttributes attrs = new ColorAttributes(true, false, Color.RED, Color.BLACK);
+        assertTrue(attrs.filled, "filled flag should be true when constructed with true");
+    }
+
+    @Test
+    void testConstructorStoresStrokedFlag() {
+        ColorAttributes attrs = new ColorAttributes(false, true, Color.RED, Color.BLACK);
+        assertTrue(attrs.stroked, "stroked flag should be true when constructed with true");
+    }
+
+    @Test
+    void testConstructorStoresFilledColor() {
+        ColorAttributes attrs = new ColorAttributes(true, false, Color.BLUE, Color.BLACK);
+        assertEquals(Color.BLUE, attrs.filledColor, "filledColor should match the constructor argument");
+    }
+
+    @Test
+    void testConstructorStoresStrokedColor() {
+        ColorAttributes attrs = new ColorAttributes(false, true, Color.RED, Color.GREEN);
+        assertEquals(Color.GREEN, attrs.strokedColor, "strokedColor should match the constructor argument");
+    }
+
+    @Test
+    void testFilledAndStrokedBothTrue() {
+        ColorAttributes attrs = new ColorAttributes(true, true, Color.RED, Color.BLUE);
+        assertTrue(attrs.filled);
+        assertTrue(attrs.stroked);
+    }
+
+    @Test
+    void testFilledAndStrokedBothFalse() {
+        ColorAttributes attrs = new ColorAttributes(false, false, Color.RED, Color.BLUE);
+        assertFalse(attrs.filled);
+        assertFalse(attrs.stroked);
+    }
+
+    @Test
+    void testNullFilledColor() {
+        ColorAttributes attrs = new ColorAttributes(true, false, null, Color.BLACK);
+        assertNull(attrs.filledColor, "filledColor should accept null");
+    }
+
+    @Test
+    void testNullStrokedColor() {
+        ColorAttributes attrs = new ColorAttributes(false, true, Color.RED, null);
+        assertNull(attrs.strokedColor, "strokedColor should accept null");
+    }
+
+    @Test
+    void testBothColorsNull() {
+        ColorAttributes attrs = new ColorAttributes(false, false, null, null);
+        assertNull(attrs.filledColor);
+        assertNull(attrs.strokedColor);
+    }
+
+    @Test
+    void testGetIDReturnsCorrectValue() {
+        ColorAttributes attrs = new ColorAttributes(false, false, Color.RED, Color.BLACK);
+        assertEquals(ColorAttributes.ID, attrs.getID());
+    }
+
+    @Test
+    void testIDConstant() {
+        assertEquals("COLOR_ATTRS", ColorAttributes.ID);
+    }
+
+    @Test
+    void testImplementsAttributes() {
+        ColorAttributes attrs = new ColorAttributes(false, false, Color.RED, Color.BLACK);
+        assertInstanceOf(Attributes.class, attrs);
+    }
+
+    @Test
+    void testToStringContainsAllFields() {
+        ColorAttributes attrs = new ColorAttributes(true, false, Color.RED, Color.BLUE);
+        String str = attrs.toString();
+        assertTrue(str.contains("filled=true"), "toString should contain filled value");
+        assertTrue(str.contains("stroked=false"), "toString should contain stroked value");
+        assertTrue(str.contains("filledColor"), "toString should contain filledColor");
+        assertTrue(str.contains("strokedColor"), "toString should contain strokedColor");
+    }
+
+    @Test
+    void testToStringWithNullColors() {
+        ColorAttributes attrs = new ColorAttributes(false, false, null, null);
+        String str = attrs.toString();
+        assertNotNull(str, "toString should not throw with null colors");
+        assertTrue(str.contains("filledColor=null"), "toString should show null filledColor");
+        assertTrue(str.contains("strokedColor=null"), "toString should show null strokedColor");
+    }
+
+    @Test
+    void testTwoInstancesAreIndependent() {
+        ColorAttributes attrs1 = new ColorAttributes(true, false, Color.RED, Color.BLACK);
+        ColorAttributes attrs2 = new ColorAttributes(false, true, Color.BLUE, Color.GREEN);
+
+        assertTrue(attrs1.filled);
+        assertFalse(attrs2.filled);
+        assertFalse(attrs1.stroked);
+        assertTrue(attrs2.stroked);
+        assertEquals(Color.RED, attrs1.filledColor);
+        assertEquals(Color.BLUE, attrs2.filledColor);
+    }
+
+    @Test
+    void testFieldsAreImmutable() {
+        Color fillColor = Color.RED;
+        Color strokeColor = Color.BLACK;
+        ColorAttributes attrs = new ColorAttributes(true, true, fillColor, strokeColor);
+
+        // Since fields are final, verify they retain their values
+        assertEquals(Color.RED, attrs.filledColor);
+        assertEquals(Color.BLACK, attrs.strokedColor);
+        assertTrue(attrs.filled);
+        assertTrue(attrs.stroked);
+    }
+}