Renamed some of the newly added tests. No functional change

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@305453 91177308-0d34-0410-b5e6-96231b3b80d8

test/std/numerics/numeric.ops/reduce/reduce.pass.cpp

@@ -0,0 +1,63 @@
+//===----------------------------------------------------------------------===//
+//
+//                     The LLVM Compiler Infrastructure
+//
+// This file is dual licensed under the MIT and the University of Illinois Open
+// Source Licenses. See LICENSE.TXT for details.
+//
+//===----------------------------------------------------------------------===//
+
+// <numeric>
+// UNSUPPORTED: c++98, c++03, c++11, c++14
+
+// template<class InputIterator>
+//     typename iterator_traits<InputIterator>::value_type
+//     reduce(InputIterator first, InputIterator last);
+
+#include <numeric>
+#include <cassert>
+
+#include "test_iterators.h"
+
+template <class Iter, class T>
+void
+test(Iter first, Iter last, T x)
+{
+    static_assert( std::is_same_v<typename std::iterator_traits<decltype(first)>::value_type,
+                                decltype(std::reduce(first, last))> );
+    assert(std::reduce(first, last) == x);
+}
+
+template <class Iter>
+void
+test()
+{
+    int ia[] = {1, 2, 3, 4, 5, 6};
+    unsigned sa = sizeof(ia) / sizeof(ia[0]);
+    test(Iter(ia), Iter(ia), 0);
+    test(Iter(ia), Iter(ia+1), 1);
+    test(Iter(ia), Iter(ia+2), 3);
+    test(Iter(ia), Iter(ia+sa), 21);
+}
+
+template <typename T>
+void test_return_type()
+{
+    T *p = nullptr;
+    static_assert( std::is_same_v<T, decltype(std::reduce(p, p))> );
+}
+
+int main()
+{
+    test_return_type<char>();
+    test_return_type<int>();
+    test_return_type<unsigned long>();
+    test_return_type<float>();
+    test_return_type<double>();
+
+    test<input_iterator<const int*> >();
+    test<forward_iterator<const int*> >();
+    test<bidirectional_iterator<const int*> >();
+    test<random_access_iterator<const int*> >();
+    test<const int*>();
+}