Regex to find the last instance of a string

Question

I am trying to use REGEX to parse a gherkin file. I have successfully split it into multiple REGEX's to accomplish what I want, but I am having a problem getting the last instance of one of the Values.

(?s)(?P<Then>Then.*?)Scenario:|$ returns all instances except the last from

# This is a sample .feature file
Feature: Authorized Logins

Users will have individual logins, gated by passwords.


Scenario: Invalid login credentials are entered

    Given Default Database is loaded
    And App is available and running
    When User enters invalid login
    Then Application should deny login

Scenario: Valid login credentials are entered

    Given Default Database is loaded
    And App is available and running
    When User enters valid login
    And display test case selection screen
    Then Application should grant login
    And display test case selection screen

Scenario: No database connection
    Given Database is stopped
    And App is available and running
    When User enters valid login
    Then Application will deny login
    And inform of no connection

The last

Then Application will deny login
    And inform of no connection

Doesn't get selected. I have tried various things, but can't seem to get it. Any suggestions?

https://regex101.com/r/iiM5X5/2

Answer 1

Brief

Right now your regex is saying: Match either (?P<Then>Then.*?)Scenario: or $ , you need to group all options together as shown below.

Code

See regex in use here

(?P<Then>Then.*?)(?:Scenario:|$)

You can also use the s modifier ( re.DOTALL ) instead of placing it in the regex as (?s) .

Answer 2

Regular expressions is a very tempting tool when it comes to parsing data. But, some data has a pre-defined structure and format rules. And, most importantly, existing parsers.

In your case, these are the BDD Gherkin feature files. behave library has an already existing parser - install behave , import and use it, sample:

from behave.parser import Parser

filename = "test.feature"
with open(filename) as f:
    feature = Parser().parse(f.read(), filename)

    print(feature.name)
    for scenario in feature.scenarios:
        print(scenario.name)
        print("-----")
        for step in scenario.steps:
            print(step.keyword, step.name)
        print("--------")