Add convert utilities to tests (copied from example/example_unicode_u…

…til.h)

Add nanodbc::test namespace.
Move TestConfig to nanodbc::test::Config.

example/example_unicode_utils.h

@@ -15,6 +15,8 @@
 #error Examples do not support the iODBC wide strings
 #endif
 
+// TODO: These convert utils need to be extracted to a private
+//       internal library to share with tests
 #ifdef NANODBC_ENABLE_UNICODE
 inline nanodbc::string convert(std::string const& in)
 {

test/base_test_fixture.h

@@ -35,34 +35,90 @@
 #include <sql.h>
 #include <sqlext.h>
 
-struct TestConfig
+namespace nanodbc
 {
-    nanodbc::string get_connection_string() const
-    {
+namespace test
+{
+
+// TODO: These convert utils need to be extracted to a private
+//       internal library to share with tests
 #ifdef NANODBC_ENABLE_UNICODE
-#ifdef NANODBC_ENABLE_BOOST
-        using boost::locale::conv::utf_to_utf;
-        return utf_to_utf<char16_t>(
-            connection_string_.c_str(), connection_string_.c_str() + connection_string_.size());
-// Workaround for confirmed bug in VS2015 and VS2017 too
-// See: https://connect.microsoft.com/VisualStudio/Feedback/Details/1403302
+inline nanodbc::string convert(std::string const& in)
+{
+    static_assert(
+        sizeof(nanodbc::string::value_type) > 1,
+        "NANODBC_ENABLE_UNICODE mode requires wide string");
+    nanodbc::string out;
+#if defined(__GNUC__) && __GNUC__ < 5
+    std::vector<wchar_t> characters(in.length());
+    for (size_t i = 0; i < in.length(); i++)
+        characters[i] = in[i];
+    const wchar_t* source = characters.data();
+    size_t size = wcsnrtombs(nullptr, &source, characters.size(), 0, nullptr);
+    if (size == std::string::npos)
+        throw std::range_error("UTF-16 -> UTF-8 conversion error");
+    out.resize(size);
+    wcsnrtombs(&out[0], &source, characters.size(), out.length(), nullptr);
 #elif defined(_MSC_VER) && (_MSC_VER >= 1900)
-        auto s = std::wstring_convert<std::codecvt_utf8_utf16<int16_t>, int16_t>().from_bytes(
-            connection_string_);
-        auto p = reinterpret_cast<char16_t const*>(s.data());
-        return nanodbc::string(p, p + s.size());
+    // Workaround for confirmed bug in VS2015 and VS2017 too
+    // See: https://connect.microsoft.com/VisualStudio/Feedback/Details/1403302
+    using wide_char_t = nanodbc::string::value_type;
+    auto s =
+        std::wstring_convert<std::codecvt_utf8_utf16<wide_char_t>, wide_char_t>().from_bytes(in);
+    auto p = reinterpret_cast<wide_char_t const*>(s.data());
+    out.assign(p, p + s.size());
 #else
-        return std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t>().from_bytes(
-            connection_string_);
+    out = std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t>().from_bytes(in);
 #endif
+    return out;
+}
+
+inline std::string convert(nanodbc::string const& in)
+{
+    static_assert(sizeof(nanodbc::string::value_type) > 1, "string must be wide");
+    std::string out;
+#if defined(__GNUC__) && __GNUC__ < 5
+    size_t size = mbsnrtowcs(nullptr, in.data(), in.length(), 0, nullptr);
+    if (size == std::string::npos)
+        throw std::range_error("UTF-8 -> UTF-16 conversion error");
+    std::vector<wchar_t> characters(size);
+    const char* source = in.data();
+    mbsnrtowcs(&characters[0], &source, in.length(), characters.size(), nullptr);
+    out.resize(size);
+    for (size_t i = 0; i < in.length(); i++)
+        out[i] = characters[i];
+#elif defined(_MSC_VER) && (_MSC_VER >= 1900)
+    // Workaround for confirmed bug in VS2015 and VS2017 too
+    // See: https://connect.microsoft.com/VisualStudio/Feedback/Details/1403302
+    using wide_char_t = nanodbc::string::value_type;
+    std::wstring_convert<std::codecvt_utf8_utf16<wide_char_t>, wide_char_t> convert;
+    auto p = reinterpret_cast<const wide_char_t*>(in.data());
+    out = convert.to_bytes(p, p + in.size());
 #else
-        return connection_string_;
+    out = std::wstring_convert<std::codecvt_utf8_utf16<char16_t>, char16_t>().to_bytes(in);
+#endif
+    return out;
+}
+#else
+inline nanodbc::string convert(std::string const& in)
+{
+    return in;
+}
 #endif
+
+struct Config
+{
+    nanodbc::string get_connection_string() const
+    {
+        return convert(connection_string_);
     }
 
     std::string connection_string_;
 };
-extern TestConfig cfg;
+
+}} // namespace nanodbc::test
+
+extern nanodbc::test::Config cfg;
 
 struct base_test_fixture
 {

test/main.cpp

@@ -7,20 +7,20 @@
 #include "base_test_fixture.h" // Must be included last!
 // clang-format on
 
-TestConfig cfg;
+nanodbc::test::Config cfg;
 
 int main(int argc, char* argv[])
 {
     try
     {
         // Specify custom command line options
         auto args = Clara::argsToVector(argc, argv);
-        Clara::CommandLine<TestConfig> cli;
+        Clara::CommandLine<nanodbc::test::Config> cli;
         cli["-c"]["--connection-string"]
             .describe("connection string to test database; if not specified, "
                       "an attempt will be made to read it from environment variables: "
                       "NANODBC_TEST_CONNSTR or NANODBC_TEST_CONNSTR_<DB>")
-            .bind(&TestConfig::connection_string_, "string");
+            .bind(&nanodbc::test::Config::connection_string_, "string");
         cli.parseInto(args, cfg);
 
         // Disable custom options to avoid Catch warnings or failures