Add Map.VolatileSource unit test

test/map/map.test.cpp

@@ -1529,3 +1529,36 @@ TEST(Map, PlacedSymbolData) {
 
     EXPECT_TRUE(test.frontend.getRenderer()->getPlacedSymbolsData().empty());
 }
+
+TEST(Map, VolatileSource) {
+    MapTest<> test{1, MapMode::Continuous};
+
+    std::atomic_int requestedTiles(0);
+    bool isVolatile = true;
+    test.fileSource->tileResponse = [&](const Resource& resource) {
+        auto expectedPolicy = isVolatile ? Resource::StoragePolicy::Volatile : Resource::StoragePolicy::Permanent;
+        EXPECT_EQ(expectedPolicy, resource.storagePolicy);
+        ++requestedTiles;
+        Response res;
+        res.noContent = true;
+        return res;
+    };
+
+    test.map.getStyle().loadJSON(R"STYLE({
+      "version": 8,
+      "layers": [{
+        "id": "water",
+        "type": "fill",
+        "source": "vector",
+        "source-layer": "water"
+      }]
+    })STYLE");
+    auto source = std::make_unique<VectorSource>("vector", Tileset{{"a/{z}/{x}/{y}"}});
+    source->setVolatile(isVolatile);
+    test.map.getStyle().addSource(std::move(source));
+
+    test.map.jumpTo(CameraOptions().withZoom(16.0));
+    test.observer.didFinishLoadingMapCallback = [&] { test.runLoop.stop(); };
+    test.runLoop.run();
+    EXPECT_EQ(8, requestedTiles);
+}