Add a test for the module

test/module-test.cc

@@ -0,0 +1,65 @@
+// Formatting library for C++ - module tests
+//
+// Copyright (c) 2012 - present, Victor Zverovich
+// All rights reserved.
+//
+// For the license information refer to format.h.
+//
+// Copyright (c) 2021 - present, Daniela Engert
+// All Rights Reserved
+// {fmt} module.
+
+import fmt;
+
+// check for macros leaking from BMI
+static bool macro_leaked = 
+#if defined(FMT_CORE_H_) || defined(FMT_FORMAT_H)
+  true;
+#else
+  false;
+#endif
+
+#include "gtest/gtest.h"
+
+// an implicitly exported namespace must be visible [module.interface]/2.2
+TEST(module_test, namespace) {
+  using namespace fmt;
+  ASSERT_TRUE(true);
+}
+
+namespace detail {
+bool oops_detail_namespace_is_visible;
+}
+
+namespace fmt {
+bool namespace_detail_invisible() {
+#if defined(FMT_HIDE_MODULE_BUGS) && \
+  defined(_MSC_FULL_VER) && _MSC_FULL_VER <= 192930036
+  // bug in msvc 16.10-pre4:
+  // the namespace is visible even when it is neither
+  // implicitly nor explicitly exported
+  return true;
+#else
+  using namespace detail;
+  // this fails to compile if fmt::detail is visible
+  return !oops_detail_namespace_is_visible;
+#endif
+}
+} // namespace fmt
+
+// the non-exported namespace 'detail' must be invisible [module.interface]/2
+TEST(module_test, detail_namespace) {
+  EXPECT_TRUE(fmt::namespace_detail_invisible());
+}
+
+// macros must not be imported from a *named* module  [cpp.import]/5.1
+TEST(module_test, macros) {
+#if defined(FMT_HIDE_MODULE_BUGS) && \
+  defined(_MSC_FULL_VER) && _MSC_FULL_VER <= 192930036
+// bug in msvc 16.10-pre4:
+// include-guard macros leak from BMI
+// and even worse: they cannot be #undef-ined
+  macro_leaked = false;
+#endif
+  EXPECT_FALSE(macro_leaked);
+}