Add hash_unordered_multimap_test

test/Jamfile.v2

@@ -93,3 +93,4 @@ run hash_multimap_test.cpp ;
 run hash_unordered_range_test.cpp ;
 
 run hash_unordered_multiset_test.cpp ;
+run hash_unordered_multimap_test.cpp ;

test/hash_unordered_multimap_test.cpp

@@ -0,0 +1,58 @@
+// Copyright 2021, 2022 Peter Dimov.
+// Distributed under the Boost Software License, Version 1.0.
+// https://www.boost.org/LICENSE_1_0.txt
+
+#if defined(__GNUC__) && __GNUC__ == 8
+# pragma GCC diagnostic ignored "-Wsign-conversion"
+#endif
+
+#include <boost/container_hash/hash.hpp>
+#include <boost/core/lightweight_test.hpp>
+#include <boost/config.hpp>
+#include <boost/config/pragma_message.hpp>
+
+#if defined(BOOST_NO_CXX11_HDR_UNORDERED_MAP)
+
+BOOST_PRAGMA_MESSAGE( "Test skipped, BOOST_NO_CXX11_HDR_UNORDERED_MAP is defined" )
+int main() {}
+
+#else
+
+#include <unordered_map>
+
+template<class T> void test()
+{
+    typedef std::unordered_multimap<T, T> map;
+    typedef boost::hash<map> hash;
+
+    int const N = 32;
+
+    std::size_t h[ N ];
+
+    map v;
+
+    for( int i = 0; i < N; ++i )
+    {
+        h[ i ] = hash()( v );
+
+        BOOST_TEST_EQ( h[ i ], hash()( v ) );
+
+        for( int j = 0; j < i; ++j )
+        {
+            BOOST_TEST_NE( h[ j ], h[ i ] );
+        }
+
+        v.insert( std::pair<T const, T>() );
+    }
+}
+
+int main()
+{
+    test<int>();
+    test<float>();
+    test<double>();
+
+    return boost::report_errors();
+}
+
+#endif