1 files changed, 116 insertions, 0 deletions
diff --git a/composeApp/src/commonTest/kotlin/coffee/liz/ecs/EntityTest.kt b/composeApp/src/commonTest/kotlin/coffee/liz/ecs/EntityTest.kt
new file mode 100644
index 0000000..e807bd2
--- /dev/null
+++ b/composeApp/src/commonTest/kotlin/coffee/liz/ecs/EntityTest.kt
@@ -0,0 +1,116 @@
+package coffee.liz.ecs
+
+import kotlin.test.*
+
+// Test components
+data class Position(val x: Float, val y: Float) : Component
+data class Velocity(val dx: Float, val dy: Float) : Component
+data class Health(val value: Int) : Component
+
+class EntityTest {
+
+    @Test
+    fun `entity has unique id`() {
+        val entity1 = Entity(1)
+        val entity2 = Entity(2)
+
+        assertNotEquals(entity1.id, entity2.id)
+    }
+
+    @Test
+    fun `can add component to entity`() {
+        val entity = Entity(0)
+        val position = Position(10f, 20f)
+
+        entity.add(position)
+
+        assertTrue(entity.has<Position>())
+        assertEquals(position, entity.get<Position>())
+    }
+
+    @Test
+    fun `can remove component from entity`() {
+        val entity = Entity(0)
+        entity.add(Position(10f, 20f))
+
+        entity.remove<Position>()
+
+        assertFalse(entity.has<Position>())
+        assertNull(entity.get<Position>())
+    }
+
+    @Test
+    fun `add returns entity for chaining`() {
+        val entity = Entity(0)
+
+        val result = entity
+            .add(Position(10f, 20f))
+            .add(Velocity(1f, 2f))
+
+        assertSame(entity, result)
+        assertTrue(entity.has<Position>())
+        assertTrue(entity.has<Velocity>())
+    }
+
+    @Test
+    fun `can replace component by adding same type`() {
+        val entity = Entity(0)
+        entity.add(Position(10f, 20f))
+        entity.add(Position(30f, 40f))
+
+        val position = entity.get<Position>()
+
+        assertNotNull(position)
+        assertEquals(30f, position.x)
+        assertEquals(40f, position.y)
+    }
+
+    @Test
+    fun `hasAll returns true when entity has all components`() {
+        val entity = Entity(0)
+        entity.add(Position(10f, 20f))
+        entity.add(Velocity(1f, 2f))
+
+        assertTrue(entity.hasAll(Position::class, Velocity::class))
+    }
+
+    @Test
+    fun `hasAll returns false when entity missing component`() {
+        val entity = Entity(0)
+        entity.add(Position(10f, 20f))
+
+        assertFalse(entity.hasAll(Position::class, Velocity::class))
+    }
+
+    @Test
+    fun `componentTypes returns all component types`() {
+        val entity = Entity(0)
+        entity.add(Position(10f, 20f))
+        entity.add(Velocity(1f, 2f))
+        entity.add(Health(100))
+
+        val types = entity.componentTypes()
+
+        assertEquals(3, types.size)
+        assertTrue(types.contains(Position::class))
+        assertTrue(types.contains(Velocity::class))
+        assertTrue(types.contains(Health::class))
+    }
+
+    @Test
+    fun `entities with same id are equal`() {
+        val entity1 = Entity(1)
+        val entity2 = Entity(1)
+
+        assertEquals(entity1, entity2)
+        assertEquals(entity1.hashCode(), entity2.hashCode())
+    }
+
+    @Test
+    fun `entities with different id are not equal`() {
+        val entity1 = Entity(1)
+        val entity2 = Entity(2)
+
+        assertNotEquals(entity1, entity2)
+    }
+}