Problem: no test infrastructure

Solution: integrate googletest, with non-cppzmq test case for a start

tests/CMakeLists.txt

@@ -0,0 +1,43 @@
+cmake_minimum_required(VERSION 3.0 FATAL_ERROR)
+
+project(cppzmq-test CXX)
+
+# place binaries and libraries according to GNU standards
+# TODO check if we should do this
+
+# include(GNUInstallDirs)
+# set(CMAKE_ARCHIVE_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR})
+# set(CMAKE_LIBRARY_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_LIBDIR})
+# set(CMAKE_RUNTIME_OUTPUT_DIRECTORY ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_BINDIR})
+
+# we use this to get code coverage
+if(CMAKE_CXX_COMPILER_ID MATCHES GNU)
+    set(CMAKE_CXX_FLAGS "${CMAKE_CXX_FLAGS} -fprofile-arcs -ftest-coverage")
+endif()
+
+include(cmake/googletest.cmake)
+fetch_googletest(
+    ${PROJECT_SOURCE_DIR}/cmake
+    ${PROJECT_BINARY_DIR}/googletest
+    )
+    
+#find_package(cppzmq)
+
+enable_testing()
+
+add_executable(
+    unit_tests
+    example_add.cpp
+    )
+
+target_link_libraries(
+    unit_tests
+    gtest_main
+    )
+
+add_test(
+  NAME
+    unit
+  COMMAND
+    ${CMAKE_BINARY_DIR}/${CMAKE_INSTALL_BINDIR}/unit_tests
+  )

tests/cmake/googletest-download.cmake

@@ -0,0 +1,20 @@
+# code copied from https://crascit.com/2015/07/25/cmake-gtest/
+cmake_minimum_required(VERSION 3.5 FATAL_ERROR)
+
+project(googletest-download NONE)
+
+include(ExternalProject)
+
+ExternalProject_Add(
+  googletest
+  SOURCE_DIR "@GOOGLETEST_DOWNLOAD_ROOT@/googletest-src"
+  BINARY_DIR "@GOOGLETEST_DOWNLOAD_ROOT@/googletest-build"
+  GIT_REPOSITORY
+    https://github.com/google/googletest.git
+  GIT_TAG
+    release-1.8.0
+  CONFIGURE_COMMAND ""
+  BUILD_COMMAND ""
+  INSTALL_COMMAND ""
+  TEST_COMMAND ""
+  )

tests/cmake/googletest.cmake

@@ -0,0 +1,32 @@
+# the following code to fetch googletest
+# is inspired by and adapted after https://crascit.com/2015/07/25/cmake-gtest/
+# download and unpack googletest at configure time
+
+macro(fetch_googletest _download_module_path _download_root)
+    set(GOOGLETEST_DOWNLOAD_ROOT ${_download_root})
+    configure_file(
+        ${_download_module_path}/googletest-download.cmake
+        ${_download_root}/CMakeLists.txt
+        @ONLY
+        )
+    unset(GOOGLETEST_DOWNLOAD_ROOT)
+
+    execute_process(
+        COMMAND
+            "${CMAKE_COMMAND}" -G "${CMAKE_GENERATOR}" .
+        WORKING_DIRECTORY
+            ${_download_root}
+        )
+    execute_process(
+        COMMAND
+            "${CMAKE_COMMAND}" --build .
+        WORKING_DIRECTORY
+            ${_download_root}
+        )
+
+    # adds the targers: gtest, gtest_main, gmock, gmock_main
+    add_subdirectory(
+        ${_download_root}/googletest-src
+        ${_download_root}/googletest-build
+        )
+endmacro()

tests/example_add.cpp

@@ -0,0 +1,8 @@
+#include "gtest/gtest.h"
+
+TEST(example, add)
+{
+    double res;
+    res = 1.0 + 2.0;
+    ASSERT_NEAR(res, 3.0, 1.0e-11);
+}

tests/main.cpp

@@ -0,0 +1,7 @@
+#include "gtest/gtest.h"
+
+int main(int argc, char** argv)
+{
+    ::testing::InitGoogleTest(&argc, argv);
+    return RUN_ALL_TESTS();
+}