According to [1], when the outline scenarios are
reported in 'expand' mode, all the outlines will
be expanded to scenarios with their test results.
Also, the step name parameters are filled in.
This is a different mode than without 'expand'
mode[2], where the scenario outlines are reported
so the step names are not filled in and there are
no test results. The "examples" are reported in
this mode.
Since pytest-bdd does report the results of each
step of an outline scenario as separate scenarios,
it looks more like the 'expand' mode, so I've
added the filling in of the parameters in the
step names to make it more compliant.
[1] https://relishapp.com/cucumber/cucumber/docs/formatters/json-output-formatter#scenario-outline-expanded
[2] https://relishapp.com/cucumber/cucumber/docs/formatters/json-output-formatter#scenario-outline