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_init.pass.cpp

@@ -0,0 +1,67 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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, class T>
+//   T reduce(InputIterator first, InputIterator last, T init);
+
+#include <numeric>
+#include <cassert>
+
+#include "test_iterators.h"
+
+template <class Iter, class T>
+void
+test(Iter first, Iter last, T init, T x)
+{
+    static_assert( std::is_same_v<T, decltype(std::reduce(first, last, init))> );
+    assert(std::reduce(first, last, init) == 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, 0);
+    test(Iter(ia), Iter(ia), 1, 1);
+    test(Iter(ia), Iter(ia+1), 0, 1);
+    test(Iter(ia), Iter(ia+1), 2, 3);
+    test(Iter(ia), Iter(ia+2), 0, 3);
+    test(Iter(ia), Iter(ia+2), 3, 6);
+    test(Iter(ia), Iter(ia+sa), 0, 21);
+    test(Iter(ia), Iter(ia+sa), 4, 25);
+}
+
+template <typename T, typename Init>
+void test_return_type()
+{
+    T *p = nullptr;
+    static_assert( std::is_same_v<Init, decltype(std::reduce(p, p, Init{}))> );
+}
+
+int main()
+{
+    test_return_type<char, int>();
+    test_return_type<int, int>();
+    test_return_type<int, unsigned long>();
+    test_return_type<float, int>();
+    test_return_type<short, float>();
+    test_return_type<double, char>();
+    test_return_type<char, 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*>();
+}