DOC: readme for building the tests

README_SETUP.md

@@ -35,9 +35,18 @@ If you encounter something like `protobufConfig.cmake` when doing `cmake ..` you
 
 ## Unit Tests
 
+### Build
+
+For the tests there is a slightly different setup required (with option `-D CMAKE_BUILD_TYPE=Debug`)
+
+1. `mkdir build && cd build/`
+2. `cmake -B . -D CMAKE_BUILD_TYPE=Debug ..`
+3. `cmake --build .`
+
+
 ### Run
 
-Build tests as described above. In the build directory, run `ctest`
+In the build directory, run `ctest`
 
 ### Framework