STDOUT and STDERR

Commands-line applications can generate output on to two streams: STDOUT and STDERR. There is no general agreement on which stream is supposed to contain what kind of data, but commonly STDOUT contains the primary output and STDERR contains logs, debug messages, etc. This is also the recommendation of the CLI guidelines.

Scrut, by default, only considers STDOUT when validating output.

You can modify this behavior by using the output_stream configuration directive or the --(no-)combine-output command-line parameters.

tip

While you can configure which output streams Scrut considers when evaluating output expecations, you can also steer this by using stream control bash primitives like some-command 2>&1.

note

The above is true for Markdown test documents. However Cram test documents default to combining STDOUT and STDERR.