diff --git a/test/test_collate.cpp b/test/test_collate.cpp
index e63ee85..50bdad2 100644
--- a/test/test_collate.cpp
+++ b/test/test_collate.cpp
@@ -12,12 +12,15 @@
 #include <iostream>
 
 template<typename Char>
-void test_comp(std::locale l, std::basic_string<Char> left, std::basic_string<Char> right, int ilevel, int expected)
+void test_comp(const std::locale& l,
+               const std::basic_string<Char>& left,
+               const std::basic_string<Char>& right,
+               const boost::locale::collate_level level,
+               const int expected)
 {
     typedef std::basic_string<Char> string_type;
-    boost::locale::collate_level level = static_cast<boost::locale::collate_level>(ilevel);
     TEST_EQ(boost::locale::comparator<Char>(l, level)(left, right), expected < 0);
-    if(ilevel == 4) {
+    if(level == boost::locale::collate_level::identical) {
         const std::collate<Char>& coll = std::use_facet<std::collate<Char>>(l);
         string_type lt = coll.transform(left.c_str(), left.c_str() + left.size());
         string_type rt = coll.transform(right.c_str(), right.c_str() + right.size());
@@ -57,11 +60,15 @@ void test_comp(std::locale l, std::basic_string<Char> left, std::basic_string<Ch
 
 #define TEST_COMP(c, _l, _r) test_comp<c>(l, _l, _r, level, expected)
 
-void compare(std::string left, std::string right, int level, int expected)
+void compare(const std::string left,
+             const std::string right,
+             const boost::locale::collate_level level,
+             const int expected)
 {
+    using boost::locale::collate_level;
     boost::locale::generator gen;
     std::locale l = gen("en_US.UTF-8");
-    if(level == 4)
+    if(level == collate_level::identical)
         TEST_EQ(l(left, right), (expected < 0));
     TEST_COMP(char, left, right);
     TEST_COMP(wchar_t, to<wchar_t>(left), to<wchar_t>(right));
@@ -72,31 +79,33 @@ void compare(std::string left, std::string right, int level, int expected)
     TEST_COMP(char32_t, to<char32_t>(left), to<char32_t>(right));
 #endif
     l = gen("en_US.ISO8859-1");
-    if(level == 4)
+    if(level == collate_level::identical)
         TEST_EQ(l(to<char>(left), to<char>(right)), (expected < 0));
     TEST_COMP(char, to<char>(left), to<char>(right));
 }
 
 void test_collate()
 {
-    int primary = 0, secondary = 1, tertiary = 2, quaternary = 3, identical = 4;
-    int le = -1, gt = 1, eq = 0;
+    constexpr int le = -1, gt = 1, eq = 0;
+    using boost::locale::collate_level;
 
-    compare("a", "A", primary, eq);
-    compare("a", "A", secondary, eq);
-    compare("A", "a", tertiary, gt);
-    compare("a", "A", tertiary, le);
-    compare("a", "A", quaternary, le);
-    compare("A", "a", quaternary, gt);
-    compare("a", "A", identical, le);
-    compare("A", "a", identical, gt);
-    compare("a", "ä", primary, eq);    //  a , ä
-    compare("a", "ä", secondary, le);  //  a , ä
-    compare("ä", "a", secondary, gt);  //  a , ä
-    compare("a", "ä", quaternary, le); //  a , ä
-    compare("ä", "a", quaternary, gt); //  a , ä
-    compare("a", "ä", identical, le);  //  a , ä
-    compare("ä", "a", identical, gt);  //  a , ä
+    compare("a", "A", collate_level::primary, eq);
+    compare("a", "A", collate_level::secondary, eq);
+    compare("A", "a", collate_level::tertiary, gt);
+    compare("a", "A", collate_level::tertiary, le);
+    compare("a", "A", collate_level::quaternary, le);
+    compare("A", "a", collate_level::quaternary, gt);
+    compare("a", "A", collate_level::identical, le);
+    compare("A", "a", collate_level::identical, gt);
+    compare("a", "ä", collate_level::primary, eq);
+    compare("a", "ä", collate_level::secondary, le);
+    compare("ä", "a", collate_level::secondary, gt);
+    compare("a", "ä", collate_level::quaternary, le);
+    compare("ä", "a", collate_level::quaternary, gt);
+    compare("a", "ä", collate_level::identical, le);
+    compare("ä", "a", collate_level::identical, gt);
+    compare("a", "a", collate_level::identical, eq);
+    compare("ä", "ä", collate_level::identical, eq);
 }
 
 BOOST_LOCALE_DISABLE_UNREACHABLE_CODE_WARNING
diff --git a/test/test_posix_collate.cpp b/test/test_posix_collate.cpp
index fbc8d15..0f16307 100644
--- a/test/test_posix_collate.cpp
+++ b/test/test_posix_collate.cpp
@@ -56,12 +56,13 @@ void test_char()
     std::cout << "- Testing at least C" << std::endl;
     std::locale l = gen("C.UTF-8");
     test_one<CharType>(l, "a", "b", -1);
+    test_one<CharType>(l, "b", "a", 1);
     test_one<CharType>(l, "a", "a", 0);
 
 #if !defined(__APPLE__) && !defined(__FreeBSD__)
     for(const std::string locale_name : {"en_US.UTF-8", "en_US.ISO8859-1"}) {
         if(!has_posix_locale(locale_name))
-            std::cout << "- " << locale_name << " not supported, skipping" << std::endl;
+            std::cout << "- " << locale_name << " not supported, skipping" << std::endl; // LCOV_EXCL_LINE
         else {
             std::cout << "- Testing " << locale_name << std::endl;
             l = gen(locale_name);
diff --git a/test/test_std_collate.cpp b/test/test_std_collate.cpp
index 8e1b39a..f4cc080 100644
--- a/test/test_std_collate.cpp
+++ b/test/test_std_collate.cpp
@@ -57,6 +57,7 @@ void test_char()
     std::locale l = gen("en_US.UTF-8");
 
     test_one<CharType>(l, "a", "b", -1);
+    test_one<CharType>(l, "b", "a", 1);
     test_one<CharType>(l, "a", "a", 0);
 
 #if defined(_LIBCPP_VERSION) && (defined(__APPLE__) || defined(__FreeBSD__))
@@ -76,7 +77,7 @@ void test_char()
                 test_one<CharType>(l, "ängel", "år", info.language() == "sv" ? 1 : -1);
             }
         } else
-            std::cout << "- " << name << " not supported, skipping" << std::endl;
+            std::cout << "- " << name << " not supported, skipping" << std::endl; // LCOV_EXCL_LINE
     }
 #endif
 }
diff --git a/test/test_winapi_collate.cpp b/test/test_winapi_collate.cpp
index b470ae4..a05eb5e 100644
--- a/test/test_winapi_collate.cpp
+++ b/test/test_winapi_collate.cpp
@@ -12,12 +12,15 @@
 #include <iomanip>
 
 template<typename Char>
-void test_comp(std::locale l, std::basic_string<Char> left, std::basic_string<Char> right, int ilevel, int expected)
+void test_comp(const std::locale& l,
+               const std::basic_string<Char>& left,
+               const std::basic_string<Char>& right,
+               const boost::locale::collate_level level,
+               const int expected)
 {
     typedef std::basic_string<Char> string_type;
-    boost::locale::collate_level level = static_cast<boost::locale::collate_level>(ilevel);
     TEST_EQ(boost::locale::comparator<Char>(l, level)(left, right), (expected < 0));
-    if(ilevel == 4) {
+    if(level == boost::locale::collate_level::identical) {
         const std::collate<Char>& coll = std::use_facet<std::collate<Char>>(l);
         string_type lt = coll.transform(left.c_str(), left.c_str() + left.size());
         string_type rt = coll.transform(right.c_str(), right.c_str() + right.size());
@@ -57,36 +60,47 @@ void test_comp(std::locale l, std::basic_string<Char> left, std::basic_string<Ch
 
 #define TEST_COMP(c, _l, _r) test_comp<c>(l, _l, _r, level, expected)
 
-void compare(std::string left, std::string right, int level, int expected)
+void compare(const std::string left,
+             const std::string right,
+             const boost::locale::collate_level level,
+             const int expected)
 {
     boost::locale::generator gen;
     std::locale l = gen("en_US.UTF-8");
-    if(level == 4)
+    if(level == boost::locale::collate_level::identical)
         TEST_EQ(l(left, right), (expected < 0));
     TEST_COMP(char, left, right);
     TEST_COMP(wchar_t, to<wchar_t>(left), to<wchar_t>(right));
+#ifdef BOOST_LOCALE_ENABLE_CHAR16_T
+    TEST_COMP(char16_t, to<char16_t>(left), to<char16_t>(right));
+#endif
+#ifdef BOOST_LOCALE_ENABLE_CHAR32_T
+    TEST_COMP(char32_t, to<char32_t>(left), to<char32_t>(right));
+#endif
 }
 
 void test_collate()
 {
-    int primary = 0, secondary = 1, tertiary = 2, quaternary = 3, identical = 4;
-    int le = -1, gt = 1, eq = 0;
+    constexpr int le = -1, gt = 1, eq = 0;
+    using boost::locale::collate_level;
 
-    compare("a", "A", primary, eq);
-    compare("a", "A", secondary, eq);
-    compare("A", "a", tertiary, gt);
-    compare("a", "A", tertiary, le);
-    compare("a", "A", quaternary, le);
-    compare("A", "a", quaternary, gt);
-    compare("a", "A", identical, le);
-    compare("A", "a", identical, gt);
-    compare("a", "ä", primary, eq);    //  a , ä
-    compare("a", "ä", secondary, le);  //  a , ä
-    compare("ä", "a", secondary, gt);  //  a , ä
-    compare("a", "ä", quaternary, le); //  a , ä
-    compare("ä", "a", quaternary, gt); //  a , ä
-    compare("a", "ä", identical, le);  //  a , ä
-    compare("ä", "a", identical, gt);  //  a , ä
+    compare("a", "A", collate_level::primary, eq);
+    compare("a", "A", collate_level::secondary, eq);
+    compare("A", "a", collate_level::tertiary, gt);
+    compare("a", "A", collate_level::tertiary, le);
+    compare("a", "A", collate_level::quaternary, le);
+    compare("A", "a", collate_level::quaternary, gt);
+    compare("a", "A", collate_level::identical, le);
+    compare("A", "a", collate_level::identical, gt);
+    compare("a", "ä", collate_level::primary, eq);
+    compare("a", "ä", collate_level::secondary, le);
+    compare("ä", "a", collate_level::secondary, gt);
+    compare("a", "ä", collate_level::quaternary, le);
+    compare("ä", "a", collate_level::quaternary, gt);
+    compare("a", "ä", collate_level::identical, le);
+    compare("ä", "a", collate_level::identical, gt);
+    compare("a", "a", collate_level::identical, eq);
+    compare("ä", "ä", collate_level::identical, eq);
 }
 
 BOOST_LOCALE_DISABLE_UNREACHABLE_CODE_WARNING