Test case that would previously run in quadratic complexity

diff --git a/tests/base/index_set_33.cc b/tests/base/index_set_33.cc
new file mode 100644 (file)
index 0000000..1e41ce0
--- /dev/null
+++ b/tests/base/index_set_33.cc
@@ -0,0 +1,48 @@
+// ---------------------------------------------------------------------
+//
+// Copyright (C) 2023 by the deal.II authors
+//
+// This file is part of the deal.II library.
+//
+// The deal.II library is free software; you can use it, redistribute
+// it, and/or modify it under the terms of the GNU Lesser General
+// Public License as published by the Free Software Foundation; either
+// version 2.1 of the License, or (at your option) any later version.
+// The full text of the license can be found in the file LICENSE.md at
+// the top level directory of deal.II.
+//
+// ---------------------------------------------------------------------
+
+
+// Test that IndexSet::add_index runs in linear complexity when adding the
+// same indices many times
+
+#include <deal.II/base/index_set.h>
+
+#include "../tests.h"
+
+
+void
+test()
+{
+  IndexSet set(20);
+
+  // Choose a large number of entries, which would time-out for quadratic
+  // complexity
+  for (unsigned int t = 0; t < 200000; ++t)
+    for (unsigned int i = 4; i < 15; ++i)
+      set.add_index(i);
+
+  set.compress();
+  deallog << "OK" << std::endl;
+}
+
+
+
+int
+main()
+{
+  initlog();
+
+  test();
+}

diff --git a/tests/base/index_set_33.output b/tests/base/index_set_33.output
new file mode 100644 (file)
index 0000000..0fd8fc1
--- /dev/null
+++ b/tests/base/index_set_33.output
@@ -0,0 +1,2 @@
+
+DEAL::OK