Added unit tes of runCommand().

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
Changed error message.

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>
Added unit test of Error().

Signed-off-by: Kouhei Maeda <mkouhei@palmtb.net>