title: ctest complains "No test configuration file found!"
body: <p>With <strong>CMake</strong> I try to execute a simple test using <strong>CTest</strong>. I have this configuration all in one directory (${CMAKE_SOURCE_DIR}):</p>
  <pre><code>~$ cat hello.cpp
  #include &lt;iostream&gt;
  
  int main() {
      std::cout &lt;&lt; &quot;hello world\n&quot;;
      return(0);
  }
  
  ~$ cat CMakeLists.txt
  cmake_minimum_required(VERSION 3.18)
  project(TEST_CTEST)
  
  enable_testing()
  add_executable(test_ctest hello.cpp)
  add_test(my_test ./build/test_ctest)
  </code></pre>
  <p>Then I execute:</p>
  <pre><code>~$ rm -rf Testing/ build/
  ~$ cmake -S . -B build
  ~$ cmake --build build
  ~$ ./build/test_ctest
  hello world
  
  ~$ ctest
  *********************************
  No test configuration file found!
  *********************************
  Usage
  
    ctest [options]
  </code></pre>
  <p>The only hint I have found in other Q&amp;A is to place <code>enable_testing()</code> into the root <code>CMakeLists.txt</code>. I feel like I just missed a little thing, but I can't find what.</p>
  <p>How do I run a test with CTest?</p>