Add new BMP tests

unitTests/test_bmpimage.cpp

@@ -0,0 +1,21 @@
+#include <exiv2/bmpimage.hpp>
+
+#include <gtest/gtest.h>
+
+#include <array>
+
+using namespace Exiv2;
+
+TEST(BmpImage, canBeOpenedWithEmptyMemIo)
+{
+    auto memIo = std::make_unique<MemIo>();
+    ASSERT_NO_THROW(BmpImage bmp(std::move(memIo)));
+}
+
+TEST(BmpImage, mimeTypeIsBmp)
+{
+    auto memIo = std::make_unique<MemIo>();
+    BmpImage bmp(std::move(memIo));
+
+    ASSERT_EQ("image/x-ms-bmp", bmp.mimeType());
+}