test: Rename string_op+= to string_op_plus_equal. Windows git doesn't like it.

git-svn-id: https://llvm.org/svn/llvm-project/libcxx/trunk@121265 91177308-0d34-0410-b5e6-96231b3b80d8

test/strings/basic.string/string.modifiers/string_op_plus_equal/char.pass.cpp

@@ -0,0 +1,33 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+
+// <string>
+
+// basic_string<charT,traits,Allocator>& operator+=(charT c);
+
+#include <string>
+#include <cassert>
+
+template <class S>
+void
+test(S s, typename S::value_type str, S expected)
+{
+    s += str;
+    assert(s.__invariants());
+    assert(s == expected);
+}
+
+int main()
+{
+    typedef std::string S;
+    test(S(), 'a', S("a"));
+    test(S("12345"), 'a', S("12345a"));
+    test(S("1234567890"), 'a', S("1234567890a"));
+    test(S("12345678901234567890"), 'a', S("12345678901234567890a"));
+}