From a9daedd8bee1b5620a933b612c3335b90bde263d Mon Sep 17 00:00:00 2001
From: Magnus Jacobsson <Magnus.Jacobsson@berotec.se>
Date: Mon, 5 Jul 2021 11:44:15 +0200
Subject: [PATCH] add optional ctest & catch2 based test infrastructure

This commit adds a CMakeLists.txt in the tests directory containing
the foundation for easily creating new test executables. It includes
creation of a shared library that the individual test executables can
be linked to, allowing them to be as small as possible.

The tests are optional and can be enabled with the CMake option
with_cxx_tests.

Also added is a first simple test case that always passes to show how
to create test cases.
---
 CMakeLists.txt        |  7 +++++++
 tests/CMakeLists.txt  | 30 ++++++++++++++++++++++++++++++
 tests/catch2_main.cpp |  3 +++
 tests/test_simple.cpp |  4 ++++
 4 files changed, 44 insertions(+)
 create mode 100644 tests/CMakeLists.txt
 create mode 100644 tests/catch2_main.cpp
 create mode 100644 tests/test_simple.cpp

diff --git a/CMakeLists.txt b/CMakeLists.txt
index bd8a27d5b..1df011e2f 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -11,6 +11,7 @@ option(with_ortho      "ORTHO features in neato layout engine." ON )
 option(with_sfdp       "sfdp layout engine." ON )
 option(with_smyrna     "SMYRNA large graph viewer (disabled by default - experimental)" OFF)
 option(use_sanitizers  "enables using address and undefined behavior sanitizer" OFF)
+option(with_cxx_tests  "enables building the C++ tests" OFF)
 
 if (enable_ltdl)
         add_definitions(-DENABLE_LTDL)
@@ -224,10 +225,16 @@ include(InstallRequiredSystemLibraries)
 include(package_info)
 include(CPack)
 
+# ==================================== Test ====================================
+Include(CTest)
+
 # ======================= Specify subdirectories to build ======================
 add_subdirectory(lib)
 add_subdirectory(plugin)
 add_subdirectory(cmd)
+if (with_cxx_tests)
+    add_subdirectory(tests)
+endif()
 
 MATH(EXPR GRAPHVIZ_PLUGIN_VERSION "${GRAPHVIZ_PLUGIN_VERSION}+1")
 set(GVPLUGIN_VERSION "${GRAPHVIZ_PLUGIN_VERSION}")
diff --git a/tests/CMakeLists.txt b/tests/CMakeLists.txt
new file mode 100644
index 000000000..5d87a4463
--- /dev/null
+++ b/tests/CMakeLists.txt
@@ -0,0 +1,30 @@
+cmake_minimum_required (VERSION 3.12 FATAL_ERROR)
+
+find_package(Catch2 REQUIRED)
+
+enable_testing()
+
+if (NOT ${CMAKE_CXX_COMPILER_ID} STREQUAL MSVC)
+    add_compile_options(-Wextra)
+endif()
+
+# for convenience, make a library that depends on everything so each
+# separate test can be as small as possible
+add_library(test_common STATIC
+            catch2_main.cpp
+    )
+set_target_properties(test_common PROPERTIES CXX_STANDARD 20)
+set_target_properties(test_common PROPERTIES CXX_STANDARD_REQUIRED ON)
+target_link_libraries(test_common PUBLIC Catch2::Catch2)
+
+macro(create_test testname)
+    add_executable(test_${testname} test_${testname}.cpp)
+    set_target_properties(test_${testname} PROPERTIES CXX_STANDARD 20)
+    set_target_properties(test_${testname} PROPERTIES CXX_STANDARD_REQUIRED ON)
+    add_test(NAME test_${testname} COMMAND test_${testname})
+    target_link_libraries(test_${testname} PRIVATE
+        test_common
+    )
+endmacro()
+
+create_test(simple)
diff --git a/tests/catch2_main.cpp b/tests/catch2_main.cpp
new file mode 100644
index 000000000..f481b16fe
--- /dev/null
+++ b/tests/catch2_main.cpp
@@ -0,0 +1,3 @@
+#define CATCH_CONFIG_MAIN
+
+#include <catch2/catch.hpp>
diff --git a/tests/test_simple.cpp b/tests/test_simple.cpp
new file mode 100644
index 000000000..f01f5c41c
--- /dev/null
+++ b/tests/test_simple.cpp
@@ -0,0 +1,4 @@
+#include <catch2/catch.hpp>
+
+TEST_CASE("always pass") {
+}
-- 
2.40.0