1 files changed, 121 insertions, 0 deletions
diff --git a/test/std/strings/string.view/string.view.ops/substr.pass.cpp b/test/std/strings/string.view/string.view.ops/substr.pass.cpp
new file mode 100644
index 0000000000000..5f9a60067b438
--- /dev/null
+++ b/test/std/strings/string.view/string.view.ops/substr.pass.cpp
@@ -0,0 +1,121 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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_view>
+
+// constexpr basic_string_view substr(size_type pos = 0, size_type n = npos) const;
+
+// Throws: out_of_range if pos > size().
+// Effects: Determines the effective length rlen of the string to reference as the smaller of n and size() - pos.
+// Returns: basic_string_view(data()+pos, rlen).
+
+#include <string_view>
+#include <algorithm>
+#include <stdexcept>
+#include <cassert>
+
+#include "test_macros.h"
+
+template<typename CharT>
+void test1(std::basic_string_view<CharT> sv, size_t n, size_t pos) {
+    std::basic_string_view<CharT> sv1;
+#ifdef TEST_HAS_NO_EXCEPTIONS
+    if (pos > sv.size())
+        return ;  // would throw if exceptions were enabled
+    sv1 = sv.substr(pos, n);
+#else
+    try {
+        sv1 = sv.substr(pos, n);
+        assert(pos <= sv.size());
+    }
+    catch (const std::out_of_range&) {
+        assert(pos > sv.size());
+        return ;
+    }
+#endif
+    const size_t rlen = std::min(n, sv.size() - pos);
+    assert (sv1.size() == rlen);
+    for (size_t i = 0; i < rlen; ++i)
+        assert(sv[pos+i] == sv1[i]);
+}
+
+
+template<typename CharT>
+void test ( const CharT *s ) {
+    typedef std::basic_string_view<CharT> string_view_t;
+
+    string_view_t sv1 ( s );
+
+    test1(sv1,  0, 0);
+    test1(sv1,  1, 0);
+    test1(sv1, 20, 0);
+    test1(sv1, sv1.size(), 0);
+
+    test1(sv1,   0, 3);
+    test1(sv1,   2, 3);
+    test1(sv1, 100, 3);
+
+    test1(sv1, 0, string_view_t::npos);
+    test1(sv1, 2, string_view_t::npos);
+    test1(sv1, sv1.size(), string_view_t::npos);
+
+    test1(sv1, sv1.size() + 1, 0);
+    test1(sv1, sv1.size() + 1, 1);
+    test1(sv1, sv1.size() + 1, string_view_t::npos);
+}
+
+int main () {
+    test ( "ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE" );
+    test ( "ABCDE");
+    test ( "a" );
+    test ( "" );
+
+    test ( L"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE" );
+    test ( L"ABCDE" );
+    test ( L"a" );
+    test ( L"" );
+
+#if TEST_STD_VER >= 11
+    test ( u"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE" );
+    test ( u"ABCDE" );
+    test ( u"a" );
+    test ( u"" );
+
+    test ( U"ABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDEABCDE" );
+    test ( U"ABCDE" );
+    test ( U"a" );
+    test ( U"" );
+#endif
+
+#if TEST_STD_VER > 11
+    {
+    constexpr std::string_view sv1 { "ABCDE", 5 };
+
+    {
+    constexpr std::string_view sv2 = sv1.substr ( 0, 3 );
+    static_assert ( sv2.size() == 3, "" );
+    static_assert ( sv2[0] == 'A', "" );
+    static_assert ( sv2[1] == 'B', "" );
+    static_assert ( sv2[2] == 'C', "" );
+    }
+
+    {
+    constexpr std::string_view sv2 = sv1.substr ( 3, 0 );
+    static_assert ( sv2.size() == 0, "" );
+    }
+
+    {
+    constexpr std::string_view sv2 = sv1.substr ( 3, 3 );
+    static_assert ( sv2.size() == 2, "" );
+    static_assert ( sv2[0] == 'D', "" );
+    static_assert ( sv2[1] == 'E', "" );
+    }
+    }
+#endif
+}