1 files changed, 51 insertions, 0 deletions
diff --git a/libcxx/test/std/containers/unord/next_prime.pass.cpp b/libcxx/test/std/containers/unord/next_prime.pass.cpp
new file mode 100644
index 00000000000..266d7f1f9d1
--- /dev/null
+++ b/libcxx/test/std/containers/unord/next_prime.pass.cpp
@@ -0,0 +1,51 @@
+//===----------------------------------------------------------------------===//
+//
+//                     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.
+//
+//===----------------------------------------------------------------------===//
+//
+// REQUIRES: long_tests
+
+// Not a portable test
+
+// <__hash_table>
+
+// size_t __next_prime(size_t n);
+
+// If n == 0, return 0, else return the lowest prime greater than or equal to n
+
+#include <__hash_table>
+#include <cassert>
+
+bool
+is_prime(size_t n)
+{
+    switch (n)
+    {
+    case 0:
+    case 1:
+        return false;
+    }
+    for (size_t i = 2; i*i <= n; ++i)
+    {
+        if (n % i == 0)
+            return false;
+    }
+    return true;
+}
+
+int main()
+{
+    assert(std::__next_prime(0) == 0);
+    for (std::size_t n = 1; n <= 100000; ++n)
+    {
+        std::size_t p = std::__next_prime(n);
+        assert(p >= n);
+        for (std::size_t i = n; i < p; ++i)
+            assert(!is_prime(i));
+        assert(is_prime(p));
+    }
+}