[core] Fix flickering caused by regression in #7586

It should be safe to invoke GeometryTileWorker::setData multiple times without invoking GeometryTileWorker::setLayers. Therefore GeometryTileWorker::redoLayout() must not consume the layers.

1 files changed, 22 insertions, 0 deletions

diff --git a/test/src/mbgl/test/stub_tile_observer.hpp b/test/src/mbgl/test/stub_tile_observer.hpp
new file mode 100644
index 0000000000..43ae4d8360
--- /dev/null
+++ b/test/src/mbgl/test/stub_tile_observer.hpp
@@ -0,0 +1,22 @@
+#pragma once
+
+#include <mbgl/tile/tile_observer.hpp>
+
+using namespace mbgl;
+
+/**
+ * An implementation of TileObserver that forwards all methods to dynamically-settable lambas.
+ */
+class StubTileObserver : public TileObserver {
+public:
+    void onTileChanged(Tile& tile) override {
+        if (tileChanged) tileChanged(tile);
+    }
+
+    void onTileError(Tile& tile, std::exception_ptr error) override {
+        if (tileError) tileError(tile, error);
+    }
+
+    std::function<void (Tile&)> tileChanged;
+    std::function<void (Tile&, std::exception_ptr)> tileError;
+};