CMake Error at .*/Modules/ExternalData.cmake:[0-9]+ \(message\):
  Data file referenced by argument

    DATA{MissingData.txt}

  corresponds to source tree path

    MissingData.txt

  that does not exist as a file \(with or without an extension\)!
Call Stack \(most recent call first\):
  .*
  MissingData.cmake:2 \(ExternalData_Add_Test\)
  CMakeLists.txt:3 \(include\)