Add unit tests for func_static creation and rendering

Confirm that func_static renders nothing without a "model" key, then the
expected number of renderables once a model is set.

include/irender.h

@@ -219,8 +219,8 @@ inline std::ostream& operator<< (std::ostream& os, const RendererLight& l)
 }
 
 /**
- * \brief
- * Interface for an object which can test its intersection with a RendererLight.
+ * \brief Interface for an object which can test its intersection with a
+ * RendererLight.
  *
  * Objects which implement this interface define a intersectsLight() function
  * which determines whether the given light intersects the object.

test/Entity.cpp

@@ -329,6 +329,14 @@ namespace
         RenderFixture(bool solid = false): renderSolid(solid)
         {}
 
+        // Convenience method to set render backend and traverse a node and its
+        // children for rendering
+        void renderSubGraph(const scene::INodePtr& node)
+        {
+            node->setRenderSystem(backend);
+            node->traverse(*this);
+        }
+
         // NodeVisitor implementation
         bool pre(const scene::INodePtr& node) override
         {
@@ -434,6 +442,43 @@ TEST_F(EntityTest, RenderLightAsLightSource)
               "lights/biground_torchflicker");
 }
 
+TEST_F(EntityTest, RenderEmptyFuncStatic)
+{
+    auto funcStatic = createByClassName("func_static");
+
+    // Func static without a model key is empty
+    RenderFixture rf;
+    funcStatic->traverse(rf);
+    EXPECT_EQ(rf.collector.lights, 0);
+    EXPECT_EQ(rf.collector.renderables, 0);
+}
+
+TEST_F(EntityTest, RenderFuncStaticWithModel)
+{
+    // Create a func_static with a model key
+    auto funcStatic = createByClassName("func_static");
+    funcStatic->getEntity().setKeyValue("model", "models/moss_patch.ase");
+
+    // We should get one renderable
+    RenderFixture rf;
+    rf.renderSubGraph(funcStatic);
+    EXPECT_EQ(rf.collector.lights, 0);
+    EXPECT_EQ(rf.collector.renderables, 1);
+}
+
+TEST_F(EntityTest, RenderFuncStaticWithMultiSurfaceModel)
+{
+    // Create a func_static with a model key
+    auto funcStatic = createByClassName("func_static");
+    funcStatic->getEntity().setKeyValue("model", "models/torch.lwo");
+
+    // This torch model has 3 renderable surfaces
+    RenderFixture rf;
+    rf.renderSubGraph(funcStatic);
+    EXPECT_EQ(rf.collector.lights, 0);
+    EXPECT_EQ(rf.collector.renderables, 3);
+}
+
 TEST_F(EntityTest, CreateAttachedLightEntity)
 {
     // Create the torch entity which has an attached light