Below is a list of useful regular expressions (regex) for annotating SpecFlow bindings. I’m treating this post as a reference and will be updating it with new items from time to time.
Singular or Plural
Support singular or plural wording.
Filter for Enum Values
If your binding takes an enumeration for an argument, you can limit the inputs from the Gherkin to just the valid values. In the snippets below, the possible values for the SortOrder argument are limited by the regex (ascending|descending) thus avoiding any runtime exeptions due to a bad value.
Step Argument Transformations
If the ascending/descending text feels a little awkward in the Gherkin, you can take the previous example one step further and add a step argument transformation to handle less technical wording. The regex in the step definition becomes (.*), and the regex in the step argument transform becomes from (A-Z|Z-A). The transform takes the more readable text “from A-Z” or “from Z-A” and converts it into a SortOrder value.
Convert 1st, 2nd, 3rd, etc to Integer
Have you ever come across awkward Gherkin like this?
When I remove the item at index 10
As it’s written, the index value 10 is easy to extract into an argument, but the wording isn’t very human friendly. Instead, you can update the wording to indicate the ordinal position without sacrificing readability and use a regex to extract the integral value.
Make “I” Optional
Repeating pronouns at the beginning of each step can get tedious. The previous example can be tweaked to remove the repetative “I"s.