Added template metaprogramming type trait test case

tests/t00034/.clang-uml

@@ -0,0 +1,12 @@
+compilation_database_dir: ..
+output_directory: puml
+diagrams:
+  t00034_class:
+    type: class
+    glob:
+      - ../../tests/t00034/t00034.cc
+    using_namespace:
+      - clanguml::t00034
+    include:
+      namespaces:
+        - clanguml::t00034

tests/t00034/t00034.cc

@@ -0,0 +1,51 @@
+#include <type_traits>
+
+namespace clanguml {
+//
+// Based on https://github.com/facebook/folly/blob/master/folly/Unit.h
+//
+namespace t00034 {
+
+struct Void {
+    constexpr bool operator==(const Void & /* unused */) const { return true; }
+    constexpr bool operator!=(const Void & /* unused */) const { return false; }
+};
+
+constexpr Void void_t{};
+
+template <typename T> struct lift_void {
+    using type = T;
+};
+
+template <> struct lift_void<void> {
+    using type = Void;
+};
+
+//
+// TODO: This is a shortcoming of libclang which parses the type of lift_void_t
+// alias as unexposed, i.e. no actual reference to T can be inferred without
+// manually parsing the string 'typename lift_void<T>::type'
+// For now, this test validates that the visitor does not crash
+//
+template <typename T> using lift_void_t = typename lift_void<T>::type;
+
+template <typename T> struct drop_void {
+    using type = T;
+};
+
+template <> struct drop_void<Void> {
+    using type = void;
+};
+
+template <typename T> using drop_void_t = typename drop_void<T>::type;
+
+struct A {
+};
+
+struct R {
+    lift_void_t<A> *la;
+    lift_void_t<void> *lv;
+};
+
+} // namespace t00034
+} // namespace clanguml

tests/t00034/test_case.h

@@ -0,0 +1,56 @@
+/**
+ * tests/t00034/test_case.cc
+ *
+ * Copyright (c) 2021 Bartek Kryza <bkryza@gmail.com>
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+
+TEST_CASE("t00034", "[test-case][class]")
+{
+    auto [config, db] = load_config("t00034");
+
+    auto diagram = config.diagrams["t00034_class"];
+
+    REQUIRE(diagram->name == "t00034_class");
+
+    REQUIRE(diagram->include.namespaces.size() == 1);
+    REQUIRE_THAT(diagram->include.namespaces,
+        VectorContains(std::string{"clanguml::t00034"}));
+
+    REQUIRE(diagram->exclude.namespaces.size() == 0);
+
+    REQUIRE(diagram->should_include("clanguml::t00034::A"));
+
+    auto model = generate_class_diagram(db, diagram);
+
+    REQUIRE(model.name() == "t00034_class");
+
+    auto puml = generate_class_puml(diagram, model);
+    AliasMatcher _A(puml);
+
+    REQUIRE_THAT(puml, StartsWith("@startuml"));
+    REQUIRE_THAT(puml, EndsWith("@enduml\n"));
+
+    REQUIRE_THAT(puml, IsClassTemplate("lift_void", "T"));
+    REQUIRE_THAT(puml, IsClassTemplate("drop_void", "T"));
+    REQUIRE_THAT(puml, IsClass(_A("Void")));
+    REQUIRE_THAT(puml, IsClass(_A("A")));
+    REQUIRE_THAT(puml, IsClass(_A("R")));
+
+    REQUIRE_THAT(puml, IsInstantiation(_A("lift_void<T>"), _A("lift_void<void>")));
+    REQUIRE_THAT(puml, IsInstantiation(_A("drop_void<T>"), _A("drop_void<Void>")));
+
+    save_puml(
+        "./" + config.output_directory + "/" + diagram->name + ".puml", puml);
+}

tests/test_cases.cc

@@ -139,6 +139,7 @@ using namespace clanguml::test::matchers;
 #include "t00031/test_case.h"
 #include "t00032/test_case.h"
 #include "t00033/test_case.h"
+#include "t00034/test_case.h"
 
 //
 // Sequence diagram tests