Debugger entered--Lisp error: (wrong-type-argument stringp nil)
  file-name-directory(nil)
  (nose-find-test-runner-in-dir-named (file-name-directory buffer-file-name) runner)
  nose-find-test-runner-names("eco/bin/test")
  mapcar(nose-find-test-runner-names ("eco/bin/test"))
  (reduce (quote (lambda ... ...)) (mapcar (quote nose-find-test-runner-names) nose-project-names))
  (let ((result ...)) (if result result nose-global-name))
  (message (let (...) (if result result nose-global-name)))
  nose-find-test-runner()
  (let* ((nose ...) (where ...) (args ...) (tnames ...)) (funcall (if debug ... ...) (format ... ... args where where tnames)))
  run-nose(nil nil nil)
  nosetests-all()
  eval((nosetests-all))
  eval-expression((nosetests-all) nil)
  call-interactively(eval-expression t nil)
  execute-extended-command(nil)
  call-interactively(execute-extended-command nil nil)
  recursive-edit()