Add test for including unguarded windows.h

If you do this, you are wrong, but apparently people expect libraries
to work around intrusive lower cased macros. Oh well.

projects/ExtraTests/CMakeLists.txt

@@ -126,6 +126,16 @@ set_tests_properties(
     PASS_REGULAR_EXPRESSION "benchmark name                                  samples       iterations    estimated"
 )
 
+# This test touches windows.h, so it should only be compiled under msvc
+if (MSVC)
+    # This test fails if it does not compile and succeeds otherwise
+    add_executable(WindowsHeader ${TESTS_DIR}/X90-WindowsHeaderInclusion.cpp)
+    set_property( TARGET WindowsHeader PROPERTY CXX_STANDARD 11 )
+    set_property( TARGET WindowsHeader PROPERTY CXX_STANDARD_REQUIRED ON )
+    set_property( TARGET WindowsHeader PROPERTY CXX_EXTENSIONS OFF )
+    target_include_directories( WindowsHeader PRIVATE ${SINGLE_INCLUDE_PATH} )
+    add_test(NAME WindowsHeader COMMAND WindowsHeader -r compact)
+endif()
 
 set( EXTRA_TEST_BINARIES
     PrefixedMacros
@@ -145,3 +155,4 @@ foreach( test ${EXTRA_TEST_BINARIES} )
     target_include_directories( ${test} PRIVATE ${SINGLE_INCLUDE_PATH} )
 endforeach()
 
+

projects/ExtraTests/X90-WindowsHeaderInclusion.cpp

@@ -0,0 +1,12 @@
+// X90-WindowsHeaderInclusion.cpp
+// Test that the Catch2 header compiles even after including windows.h
+// without defining NOMINMAX first. As an FYI, if you do that, you are
+// wrong.
+
+#include <windows.h>
+#define CATCH_CONFIG_MAIN
+#include <catch2/catch.hpp>
+
+TEST_CASE("Catch2 did survive compilation with windows.h", "[compile-test]") {
+    SUCCEED();
+}