title: ctest cannot run with simple command
body: <p>I have the ctest setting and work fine with all executable I've built for the project. The problem is I want to add some test with a system command, it has nothing to do with program in the solution, I cannot get it run by ctest. </p>
  
  <p>I added a simple test as below, it just run the command <strong>echo</strong>: </p>
  
  <pre><code>add_test(NAME toto_test COMMAND echo bla bla bla)
  </code></pre>
  
  <p>Then the when I run ctest, I got the error</p>
  
  <pre><code>Start  1: toto_test
  Could not find executable echo
  Looked in the following places:
  echo
  echo.exe
  Release/echo
  Release/echo.exe
  Release/echo
  Release/echo.exe
  Unable to find executable: echo
  1/10 Test  #1: toto_test ........................***Not Run   0.00 sec
  
  The following tests FAILED:
        1 - toto_test (Not Run)
  Errors while running CTest
  </code></pre>
  
  <p>And when I run ctest with verbose option, I get</p>
  
  <pre><code>Constructing a list of tests
  Done constructing a list of tests
  Updating test list for fixtures
  Added 0 tests to meet fixture requirements
  Checking test dependency graph...
  Checking test dependency graph end
  test 1
      Start 1: toto_test
  Could not find executable echo
  Looked in the following places:
  echo
  echo.exe
  Release/echo
  Release/echo.exe
  Release/echo
  Release/echo.exe
  
  1: Test command:  "bla" "bla" "bla"
  Unable to find executable: echo
  1/1 Test #1: toto_test ........................***Not Run   0.00 sec
  
  0% tests passed, 1 tests failed out of 1
  
  Total Test time (real) =   0.02 sec
  
  The following tests FAILED:
        1 - toto_test (Not Run)
  Errors while running CTest
  </code></pre>
  
  <p>Can anyone come to help please.
  Thanks a lot</p>