[WIP] Introduced CMake based build procedure and first unit/funcitonal tests created

.circleci/config.yml

@@ -310,6 +310,17 @@ jobs:
           build_kind: 'cmake'
           generate: 'false'
 
+      - run:
+          name: "Execute the C++ tests"
+          command: |
+            # compile the tests (it would probably would be better to do this when
+            # compiling the rest of Grackle)
+            cmake -DGRACKLE_BUILD_TESTS=ON -Bbuild
+            cmake --build build
+            # execute the tests
+            cd build
+            ctest
+
 # TODO: once we merge in GH-#208, we need to issue a new gold standard, and then we should
 #       issue a followup PR where we uncomment the remainder of this test
   test-standalone-pygrackle:

CMakeLists.txt

@@ -22,6 +22,12 @@ endif()
 cmake_minimum_required(VERSION 3.16)
 cmake_policy(SET CMP0077 NEW)
 cmake_policy(SET CMP0082 NEW)
+
+if (CMAKE_VERSION VERSION_GREATER_EQUAL 3.24)
+  cmake_policy(SET CMP0135 NEW) # makes automatic dependency downloads more
+                                # robust (& addresses noisy warnings)
+endif()
+
 project(Grackle VERSION ${_GRACKLE_VERSION_NO_DEVTAG} LANGUAGES C CXX Fortran)
 
 # Specify that `./cmake` contains cmake modules defining useful functionality
@@ -184,6 +190,21 @@ endif()
 # -----
 # (this is where we will add targets for integration tests)
 
+# Add BUILD_TESTS option available
+option(GRACKLE_BUILD_TESTS "build Grackle tests using GoogleTest" OFF)
+
+# if desired, setup Grackle's tests that use GoogleTest (this has no impact on
+# the tests run via pytest, those are handled outside of cmake)
+if(GRACKLE_BUILD_TESTS)
+  # setup GoogleTest framework (search for an installed copy on the machine
+  # OR download it & add its compilation to the rest of the build procedure)
+  include(setup_GTest)
+  # load CMake's built-in module that defines functions to registering unit
+  # tests implemented with GoogleTest into CMake's test-runner, CTest
+  include(GoogleTest)
+  enable_testing() # enable the test-runner, CTest
+  add_subdirectory(tests) # declare the recipes for each test
+endif()
 
 # Packaging
 # ---------

cmake/setup_GTest.cmake

@@ -0,0 +1,35 @@
+# This file includes logic for setting up GoogleTest
+find_package(GTest)
+
+if (NOT GTest_FOUND)
+    message(STATUS
+    "Preparing to download GTest from GitHub & configure its build. Don't "
+    "worry about any mentions of Python in the following text -- that is "
+    "only used internally by the Google test build"
+    )
+
+    # NOTE: it is idiomatic to use FetchContent with a git hash rather than the
+    # name of a tag or branch (since the latter 2 can freely change). If we use
+    # the name of a tag/branch, then CMake will query GitHub on every
+    # subsequent build to check whether the tag/branch is still the same
+
+    include(FetchContent)
+    FetchContent_Declare(
+      googletest # the url contains the hash for v1.13.0
+      URL https://github.com/google/googletest/archive/b796f7d44681514f58a683a3a71ff17c94edb0c1.zip
+    )
+
+    # For Windows: Prevent overriding the parent project's compiler/linker settings
+    set(gtest_force_shared_crt ON CACHE BOOL "" FORCE)
+    FetchContent_MakeAvailable(googletest)
+
+elseif("${CMAKE_VERSION}" VERSION_LESS "3.20")
+    # CMake's built-in `FindGTest` module imported targets have different names
+    # in earlier CMake versions
+    add_library(GTest::gtest ALIAS GTest::GTest)
+    add_library(GTest::gtest_main ALIAS GTest::Main)
+endif()
+
+if (NOT TARGET GTest::gtest_main)
+    message("Target GTest:: stuff MISSING")
+endif()

src/CMakeLists.txt

@@ -0,0 +1,2 @@
+add_subdirectory(clib)
+add_subdirectory(example)

src/clib/CMakeLists.txt

@@ -141,6 +141,9 @@ add_library(Grackle_Grackle
   phys_constants.h
   utils.h
 
+  # C wrappers
+  c_wrappers/wrap_interpolators_g.c
+
   # Fortran public headers
   ../include/grackle.def
   ../include/grackle_fortran_interface.def