Added unit test for header sizes

Test/BmpHeader.cpp

@@ -0,0 +1,27 @@
+#include <BmpHeader.h>
+#include "Catch2.h"
+
+using namespace Leonetienne::BmpPP;
+
+// Tests that the reported header sizes are correct
+TEST_CASE(__FILE__"/DoHeaderSizesMatch", "[Header]")
+{
+    BmpHeader header;
+
+    SECTION("DibHeader size") {
+        REQUIRE(header.dibHeader.dibHeaderSize == header.dibHeader.NBYTES);
+        REQUIRE(header.dibHeader.dibHeaderSize == 40);
+    }
+
+    SECTION("FileHeader size") {
+        REQUIRE(header.fileHeader.NBYTES == 14);
+    }
+
+    SECTION("RenderedHeader size") {
+        const std::vector<std::uint8_t> headerBytes = header.ToBytes();
+
+        REQUIRE(headerBytes.size() == header.fileHeader.NBYTES + header.dibHeader.NBYTES);
+    }
+
+    return;
+}