merge(3p/immer): Subtree merge at 'ad3e3556d' as 'third_party/immer'

Change-Id: I9636a41ad44b4218293833fd3e9456d9b07c731b

third_party/immer/test/memory/refcounts.cpp

@@ -0,0 +1,62 @@
+//
+// immer: immutable data structures for C++
+// Copyright (C) 2016, 2017, 2018 Juan Pedro Bolivar Puente
+//
+// This software is distributed under the Boost Software License, Version 1.0.
+// See accompanying file LICENSE or copy at http://boost.org/LICENSE_1_0.txt
+//
+
+#include <immer/refcount/no_refcount_policy.hpp>
+#include <immer/refcount/refcount_policy.hpp>
+#include <immer/refcount/unsafe_refcount_policy.hpp>
+
+#include <catch.hpp>
+
+TEST_CASE("no refcount has no data")
+{
+    static_assert(std::is_empty<immer::no_refcount_policy>{}, "");
+}
+
+template <typename RefcountPolicy>
+void test_refcount()
+{
+    using refcount = RefcountPolicy;
+
+    SECTION("starts at one")
+    {
+        refcount elem{};
+        CHECK(elem.dec());
+    }
+
+    SECTION("disowned starts at zero")
+    {
+        refcount elem{immer::disowned{}};
+        elem.inc();
+        CHECK(elem.dec());
+    }
+
+    SECTION("inc dec")
+    {
+        refcount elem{};
+        elem.inc();
+        CHECK(!elem.dec());
+        CHECK(elem.dec());
+    }
+
+    SECTION("inc dec unsafe")
+    {
+        refcount elem{};
+        elem.inc();
+        CHECK(!elem.dec());
+        elem.inc();
+        elem.dec_unsafe();
+        CHECK(elem.dec());
+    }
+}
+
+TEST_CASE("basic refcount") { test_refcount<immer::refcount_policy>(); }
+
+TEST_CASE("thread unsafe refcount")
+{
+    test_refcount<immer::unsafe_refcount_policy>();
+}