make it compile with cmake.

tests/CMakeLists.txt

@@ -0,0 +1,21 @@
+# Testing library
+FetchContent_Declare(
+  catch
+  GIT_REPOSITORY https://github.com/catchorg/Catch2.git
+  GIT_TAG v2.13.6)
+FetchContent_MakeAvailable(catch)
+# Adds Catch2::Catch2
+
+
+# Tests need to be added as executables first
+add_executable(testlib tests.cpp)
+
+# I'm using C++17 in the test
+target_compile_features(testlib PRIVATE cxx_std_17)
+
+# Should be linked to the main library, as well as the Catch2 testing library
+target_link_libraries(testlib PRIVATE inc Catch2::Catch2)
+
+# If you register a test, then ctest and make test will run it.
+# You can also run examples and check the output, as well.
+add_test(NAME testlibtest COMMAND testlib) # Command can be a target

tests/tests.cpp

@@ -1 +1,2 @@
-#include "tests.h"
+#define CATCH_CONFIG_MAIN
+#include <catch2/catch.hpp>