From 3c6fdc98a249ec032466317fef181ba5e469e85e Mon Sep 17 00:00:00 2001
From: Matthias Maier <tamiko@43-1.org>
Date: Fri, 27 Oct 2023 02:00:17 -0500
Subject: [PATCH] tests: add more tests for Lazy<T>

 - verify that we can call the interface in const context
 - add another test that checks whether we do the right thing with
   concurrent threads
---
 tests/base/lazy_02.cc               |  2 +-
 tests/base/lazy_03.cc               | 58 +++++++++++++++++++++++++++++
 tests/base/lazy_03.output           |  2 +
 tests/base/lazy_04.cc               | 55 +++++++++++++++++++++++++++
 tests/base/lazy_04.threads=4.output |  4 ++
 5 files changed, 120 insertions(+), 1 deletion(-)
 create mode 100644 tests/base/lazy_03.cc
 create mode 100644 tests/base/lazy_03.output
 create mode 100644 tests/base/lazy_04.cc
 create mode 100644 tests/base/lazy_04.threads=4.output

diff --git a/tests/base/lazy_02.cc b/tests/base/lazy_02.cc
index 2130279a27..bb00243cb4 100644
--- a/tests/base/lazy_02.cc
+++ b/tests/base/lazy_02.cc
@@ -1,6 +1,6 @@
 // ---------------------------------------------------------------------
 //
-// Copyright (C) 2005 - 2021 by the deal.II authors
+// Copyright (C) 2023 by the deal.II authors
 //
 // This file is part of the deal.II library.
 //
diff --git a/tests/base/lazy_03.cc b/tests/base/lazy_03.cc
new file mode 100644
index 0000000000..48c7734ad1
--- /dev/null
+++ b/tests/base/lazy_03.cc
@@ -0,0 +1,58 @@
+// ---------------------------------------------------------------------
+//
+// 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.
+//
+// ---------------------------------------------------------------------
+
+//
+// Use Lazy<T> in const context:
+//
+
+#include <deal.II/base/lazy.h>
+
+#include <iostream>
+
+#include "../tests.h"
+
+using namespace dealii;
+
+class Container
+{
+public:
+  int
+  get() const
+  {
+    lazy_integer.ensure_initialized([]() { return 42; });
+
+    if (lazy_integer.has_value())
+      return lazy_integer.value();
+
+    // unreachable
+    return lazy_integer.value_or_initialize([]() { return 43; });
+  }
+
+private:
+  Lazy<int> lazy_integer;
+};
+
+int
+main()
+{
+  initlog();
+
+  Container foo;
+
+  foo.get();
+
+  deallog << "OK!" << std::endl;
+  return 0;
+}
diff --git a/tests/base/lazy_03.output b/tests/base/lazy_03.output
new file mode 100644
index 0000000000..5cfb783b8f
--- /dev/null
+++ b/tests/base/lazy_03.output
@@ -0,0 +1,2 @@
+
+DEAL::OK!
diff --git a/tests/base/lazy_04.cc b/tests/base/lazy_04.cc
new file mode 100644
index 0000000000..96db2318cc
--- /dev/null
+++ b/tests/base/lazy_04.cc
@@ -0,0 +1,55 @@
+// ---------------------------------------------------------------------
+//
+// 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.
+//
+// ---------------------------------------------------------------------
+
+//
+// Use Lazy<T> concurrently
+//
+
+#include <deal.II/base/lazy.h>
+
+#include <iostream>
+
+#include "../tests.h"
+
+using namespace dealii;
+
+int
+main()
+{
+  initlog();
+
+  Lazy<int> lazy_integer;
+
+  const auto foo = [&]() {
+    lazy_integer.ensure_initialized([&]() {
+      deallog << "... [ initialized ] ... " << std::endl;
+      return 42;
+    });
+  };
+
+  Threads::Task<> t1 = Threads::new_task(foo);
+  Threads::Task<> t2 = Threads::new_task(foo);
+  Threads::Task<> t3 = Threads::new_task(foo);
+  Threads::Task<> t4 = Threads::new_task(foo);
+  t4.join();
+  t3.join();
+  t2.join();
+  t1.join();
+
+  deallog << "Object: " << lazy_integer.value() << std::endl;
+
+  deallog << "OK!" << std::endl;
+  return 0;
+}
diff --git a/tests/base/lazy_04.threads=4.output b/tests/base/lazy_04.threads=4.output
new file mode 100644
index 0000000000..879d648677
--- /dev/null
+++ b/tests/base/lazy_04.threads=4.output
@@ -0,0 +1,4 @@
+
+DEAL::... [ initialized ] ... 
+DEAL::Object: 42
+DEAL::OK!
-- 
2.39.5