Target name adjusted.

test/CMakeLists.txt

 target_include_directories(Catch INTERFACE "catch")
 
 
-add_library(testmain TestMain.cpp)
-target_link_libraries(testmain Catch)
+add_library(TestMain TestMain.cpp)
+target_link_libraries(TestMain Catch)
 
 
 function(add_test_suite name)
     add_executable(${name} ${name}.cpp)
-    target_link_libraries(${name} testmain)
+    target_link_libraries(${name} TestMain)
     add_test(NAME ${name} COMMAND ${name})
 endfunction()