[core] Tests for style with unused sources

test/fixtures/resources/style-unused-sources.json

@@ -0,0 +1,36 @@
+{
+  "version": 8,
+  "name": "Test",
+  "sources": {
+    "usedsource": {
+      "url": "test/fixtures/resources/source_vector.json",
+      "type": "vector"
+    },
+    "unusedsource": {
+      "url": "test/fixtures/resources/source_vector.json",
+      "type": "vector"
+    }
+  },
+  "sprite": "test/fixtures/resources/sprite",
+  "glyphs": "test/fixtures/resources/glyphs.pbf",
+  "layers": [{
+    "id": "usedlayer",
+    "type": "symbol",
+    "source": "usedsource"
+  }, {
+    "id":  "unusedlayeropacity",
+    "type": "symbol",
+    "source": "unusedsource",
+    "paint" : {
+        "icon-opacity" : 0,
+        "text-opacity" : 0
+    }
+  }, {
+    "id":  "unusedlayervisibility",
+    "type": "symbol",
+    "source": "unusedsource",
+    "layout" : {
+        "visibility" : "none"
+    }
+  }]
+}

test/style/unused_sources.cpp

@@ -0,0 +1,111 @@
+#include "../fixtures/util.hpp"
+#include "../fixtures/mock_file_source.hpp"
+#include "../fixtures/mock_view.hpp"
+
+#include <mbgl/style/style.hpp>
+#include <mbgl/map/view.hpp>
+#include <mbgl/storage/file_source.hpp>
+#include <mbgl/map/map_data.hpp>
+#include <mbgl/map/transform.hpp>
+#include <mbgl/util/exception.hpp>
+#include <mbgl/util/io.hpp>
+#include <mbgl/util/run_loop.hpp>
+#include <mbgl/util/texture_pool.hpp>
+#include <mbgl/util/thread.hpp>
+
+namespace mbgl {
+
+class MockStyleObserver: public Style::Observer {
+public:
+    using MockStyleObserverCallback = std::function<void(std::exception_ptr, Style*)>;
+
+    MockStyleObserver(View& view_,
+                      FileSource& fileSource_,
+                      const MockStyleObserverCallback& callback_)
+        : data(MapMode::Still, GLContextMode::Unique, view_.getPixelRatio()),
+          style(std::make_unique<Style>(data)),
+          transform(view_, ConstrainMode::HeightOnly),
+          callback(callback_) {
+        util::ThreadContext::setFileSource(&fileSource_);
+
+        transform.resize({{ 1000, 1000 }});
+        transform.setLatLngZoom({0, 0}, 16);
+
+        const std::string style_ = util::read_file("test/fixtures/resources/style-unused-sources.json");
+        style->setJSON(style_, "");
+        style->setObserver(this);
+    }
+
+    ~MockStyleObserver() {
+        cleanup();
+    }
+
+    void cleanup() {
+        style.reset();
+    }
+
+    void update() {
+        const auto now = Clock::now();
+
+        data.setAnimationTime(now);
+        transform.updateTransitions(now);
+
+        style->cascade();
+        style->recalculate(16);
+        style->update(transform.getState(), texturePool);
+    }
+
+    // Style::Observer implementation.
+    void onTileDataChanged() override {
+        update();
+
+        if (style->isLoaded()) {
+            callback(nullptr, style.get());
+        }
+    }
+
+    void onResourceLoadingFailed(std::exception_ptr error) override {
+        callback(error, style.get());
+    }
+
+private:
+    MapData data;
+    std::unique_ptr<Style> style;
+    Transform transform;
+    TexturePool texturePool;
+
+    MockStyleObserverCallback callback;
+};
+
+TEST(Style, UnusedSources) {
+    util::RunLoop loop;
+
+    MockView view;
+    MockFileSource fileSource(MockFileSource::Success, "");
+
+    auto callback = [&loop](std::exception_ptr error, Style* style) {
+        EXPECT_TRUE(error == nullptr);
+        loop.stop();
+
+        Source *usedSource = style->getSource("usedsource");
+        EXPECT_TRUE(usedSource);
+        EXPECT_TRUE(usedSource->isLoaded());
+
+        Source *unusedSource = style->getSource("unusedsource");
+        EXPECT_TRUE(unusedSource);
+        EXPECT_FALSE(unusedSource->isLoaded());
+    };
+
+    std::unique_ptr<util::Thread<MockStyleObserver>> observer(
+        std::make_unique<util::Thread<MockStyleObserver>>(
+            util::ThreadContext{"Map", util::ThreadType::Map, util::ThreadPriority::Regular}, view, fileSource, callback));
+
+    loop.run();
+
+    // Needed because it will make the Map thread
+    // join and cease logging after this point.
+    observer->invoke(&MockStyleObserver::cleanup);
+    observer.reset();
+}
+
+} // namespace mbgl

test/test.gypi

@@ -91,6 +91,7 @@
         'style/pending_resources.cpp',
         'style/resource_loading.cpp',
         'style/style_layer.cpp',
+        'style/unused_sources.cpp',
 
         'sprite/sprite_atlas.cpp',
         'sprite/sprite_image.cpp',