rostest file layout- can't find/tries to compile/no rule to make target, existing .test file

edit

If I compile my test bench using rosbuild_add_gtest then roscore is normally not running, and the test fails to connect. Which is why I'm trying to setup an rostest file.

I have written a differential_drive.test file in differential_drive/smurf/ ie. differential_drive/smurf/differential_drive.test

FYI smurf directory name used to differentiate values, only for testing/debugging.

Just FYI ls output from differential_drive dir:

$ ls
bin  build  CMakeLists.txt  launch  lib  mainpage.dox  Makefile  manifest.xml  msg  msg_gen  smurf  src  test

I can successfully run this test using:

$ rostest smurf/differential_drive.test
... logging to /home/tobor/.ros/log/rostest-meltybrain-17188.log
[ROSUNIT] Outputting test results to /home/tobor/.ros/test_results/differential_drive/rostest-smurf_differential_drive.xml
testdifferential_drive_ros_tests ... ok

[ROSTEST]-----------------------------------------------------------------------

...

SUMMARY
 * RESULT: SUCCESS
 * TESTS: 6
 * ERRORS: 0
 * FAILURES: 0

rostest log file is in /home/tobor/.ros/log/rostest-meltybrain-17188.log

However I am having trouble setting up the CMakeLists.txt file to run this automatically.

Here are the relevent CMakeLists.txt lines:

rosbuild_add_executable(
  test_2/differential_drive_ros_tests
  TestRunner.cpp
...
)
rosbuild_add_gtest_build_flags(test_2/differential_drive_ros_tests)
rosbuild_add_rostest(smurf/differential_drive.test)

Some make test output:

[100%] Built target test_2/differential_drive_ros_tests
[100%] Built target tests
make[3]: *** No rule to make target '../test/smurf/differential_drive.test', needed by 'test/CMakeFiles/rostest_smurf_differential_drive.test'.  Stop.
make[2]: *** [test/CMakeFiles/rostest_smurf_differential_drive.test.dir/all] Error 2

Any ideas?