Custom output

You can implement your own reporting of specs2 specifications:

• using the Notifier trait which acts like a listener
• using a Printer which gives you more flexibility for reporting exactly what you want
• using a Reporter which allow you to even change the default flow for reporting specifications: selection -> execution -> printing

Notifier

The org.specs2.reporter.Notifier trait can be used to report execution events. It notifies of the following:

Event	Description
specification start	the beginning of a specification, with its name
specification end	the end of a specification, with its name
context start	the beginning of a sub-level when the specification is seen as a tree or Fragments
context end	the end of a sub-level when the specification is seen as a tree or Fragments
text	any Text fragment that needs to be displayed
example start	the beginning of an example
example result	success / failure / error / skipped / pending

All those notifications come with a location (to trace back to the originating fragment in the Specification) and a duration when relevant (i.e. for examples).

You can then using the notifier argument to pass the name of your custom notifier:

sbt> testOnly *BinarySpec* -- notifier org.acme.reporting.FtpNotifier

Printer

The org.specs2.reporter.Printer trait defines how to output each fragment of the specification. The only method to implement is:

def fold(env: Env, spec: SpecStructure): Fold[Fragment]

So what you need to create is a Fold over the executing specification. What is it? A Fold is composed of 3 operations:

trait Fold[R, A, B] {
  type S

  def start: Eff[R, S]
  def fold: (S, A) => S
  def end(s: S): Eff[R, B]
}

• start is an initial state of type S. By using some state you can accumulate information about the execution of the whole specification
• fold is the function calculating the next state based on the current Fragment and the previous state
• end take the last state and returns a computation doing the last action like reporting the final statistics

Once you’ve defined your Printer trait you can use the printer argument like so:

sbt> testOnly *BinarySpec* -- printer org.acme.reporting.LatexPrinter

Reporter

The org.specs2.reporter.Reporter trait defines the full lifecycle for running specifications:

// prepare the environment before any reporting
def prepare(env: Env, printers: List[Printer]): List[SpecStructure] => Action[Unit]

// finalize the reporting (to save overall statistics for example)
def finalize(env: Env, printers: List[Printer]): List[SpecStructure] => Action[Unit]

/**
 * report a spec structure with the given printers
 *
 * The default implementation selects fragments to execute, executes them and uses the printers to
 * display results
 */
def report(env: Env, printers: List[Printer]): SpecStructure => Action[Unit]

Troubleshooting

If your custom Notifier or Printer fails to be instantiated you can re-run the execution with the verbose argument in order to get an error message and a stack trace.