ENH use variadic templates args in scatter and figure

.gitignore

@@ -33,6 +33,13 @@
 
 # Build
 /examples/build/*
+/contrib/unittests_catch2/build/*
+/contrib/unittests_catch2/cmake-
+/contrib/unittests_catch2/build/*
+/contrib/unittests_catch2/cmake-*
 
 # vim temp files
 *.sw*
+
+# IDE directories
+.idea

contrib/README.md

@@ -30,3 +30,15 @@ The `WinBuild.cmd` will set up temporal ENV variables and build binaries in (mat
 
 3. Find exe files in examples/build/Release
 Note: platforms folder is necessary to make qt works.
+
+## Unit Tests
+
+```cmd
+> cd contrib/unittests_catch2
+> cmake -S . -B "./build"
+> cd build
+> make
+> ./run_MatplotlibcppTests
+```
+See `unittests_catch/2README` for more details.
+

contrib/unittests_catch2/CMakeLists.txt

@@ -0,0 +1,101 @@
+# From this directory:
+# *WARNING* if you use a virtual python environment, you must have activated it before.
+# ./configure
+# then follow instructions
+# cmake -S . -B /tmp --build doit aussi fonctionner
+
+cmake_minimum_required(VERSION 3.15)
+
+project(MatplotlibcppTests
+        DESCRIPTION "matplotlibcpp unit tests"
+        LANGUAGES CXX)
+
+if(${USE_VIRTUEL_ENV})
+    set(ENV{PATH} "$ENV{VIRTUAL_ENV}/bin:$ENV{PATH}")
+endif()
+
+set(PROJECT_VERSION_MAJOR  0)
+set(PROJECT_VERSION_MINOR 0)
+set(PROJECT_VERSION_PATCH 0)
+set(PROJECT_VERSION_TWEAK 1)
+set(PROJECT_VERSION ${PROJECT_VERSION_MAJOR}.${PROJECT_VERSION_MINOR}.${PROJECT_VERSION_PATCH}.${PROJECT_VERSION_TWEAK})
+
+# -----------------------------------------------
+# -- CMake's variables
+set(CMAKE_VERBOSE_MAKEFILE ON CACHE BOOL "Verbose Makefile" FORCE)
+set(CMAKE_INCLUDE_CURRENT_DIR ON)
+
+# -----------------------------------------------
+# -- Catch
+set(CATCH_MAIN ON)
+option(BUILD_TESTING "Build nemesis-cpp testing" ${CATCH_MAIN}) 
+
+# Prepare "Catch" library for other executables
+add_library(Catch INTERFACE)
+target_include_directories(Catch INTERFACE ${PROJECT_SOURCE_DIR})
+
+# -----------------------------------------------
+# -- Python
+set(PYTHON_VERSION "3.7")
+find_package (Python3 COMPONENTS Interpreter Development)
+# Valable pour un environnement python dans un python, dans un environnement virtuel ou dans un env spack,
+set(SITE_PACKAGES "${Python3_SITELIB}")
+set(NUMPY_INCLUDE_DIR "${SITE_PACKAGES}/numpy/core/include/numpy")
+set(NUMPY_LIB_DIR "${SITE_PACKAGES}/numpy/core")
+
+# -----------------------------------------------
+# -- the project
+set(PRJ_FILES "./tu_main.cpp;./tu_matplotlibcpp.cpp")
+message(STATUS "PRJ_FILES = ${PRJ_FILES}")
+set(TU_EXE "run_${PROJECT_NAME}")
+
+set(MPLCPP_INCLUDE "${CMAKE_CURRENT_SOURCE_DIR}/../../")
+message(STATUS "MPLCPP_INCLUDE = ${MPLCPP_INCLUDE}")
+# -----------------------------------------------
+# -- rpath ...
+
+# If your compiler is not in a standard path of your OS
+if(${USE_CUSTOM_COMPILER})
+    execute_process(COMMAND bash "-c" "LANG=C ${CMAKE_CXX_COMPILER} -print-search-dirs | sed -n 's/libraries: =//gp' | tr -s ':' ';'"
+    OUTPUT_VARIABLE GNU_LIBRARIES_SEARCH_DIR)
+
+    find_library(STDCPP_LIB stdc++ PATHS ${GNU_LIBRARIES_SEARCH_DIR})
+    get_filename_component(_COMPILER_LIB_DIR ${STDCPP_LIB} DIRECTORY)
+    set(COMPILER_RPATH_FLAGS "-Wl,-rpath,${_COMPILER_LIB_DIR}")
+endif()
+
+# -----------------------------------------------
+# -- build executable
+add_executable(${TU_EXE} ${PRJ_FILES})
+add_test(NAME matplotlibcpp_tests
+         COMMAND ${TU_EXE})
+
+target_compile_features(${TU_EXE}
+        PRIVATE
+            cxx_std_17
+            )
+target_compile_definitions(${TU_EXE}
+        PRIVATE
+            USE_VARIADIC_TEMPLATES_ARGS
+            CATCH_UNIT_TESTS)
+target_compile_options(${TU_EXE}
+            PRIVATE
+            -fconcepts
+            )
+target_include_directories(${TU_EXE}
+        PRIVATE
+            ${Python3_INCLUDE_DIRS}
+            ${NUMPY_INCLUDE_DIR}
+            ${MPLCPP_INCLUDE}
+            ${CMAKE_BINARY_DIR}
+            )
+target_link_libraries(${TU_EXE}
+        PRIVATE
+            ${Python3_LIBRARIES}
+            -lstdc++fs
+            )
+target_link_options(${TU_EXE}
+        PRIVATE
+            ${COMPILER_RPATH_FLAGS}
+            )
+

contrib/unittests_catch2/README.md

@@ -0,0 +1,14 @@
+# Tests with Catch2
+
+Here some tests using [Catch2](https://github.com/catchorg/Catch2).
+
+Only tested on Ubuntu and CentOS 7, with `gcc` 6.2, 6.3 and 8.3.
+
+**warning** I force `Qt5Agg` backend. But it should work with other backend, except 'Agg'.
+
+For running the tests :
+
+    cd <matplotlibcpp_home>/contrib/tests_catch2
+    cmake -S . -B "./build"
+    cd build
+    make