gherkin: Scenario Outline variable subsitution not working for variables that contain special regex characters

[ghost]

It was suggested to me in cucumber/cucumber-js#1322 that I create an issue here instead.

Summary

We often use phrases like "is triggered" and "is not triggered". In scenario outlines. We phrase it as "the thing <is (not) triggered>". But when running the tests with cucumber-js, the step is not found because the variable is not replaced properly due to its parenthesis. I did not test any further but I reckon that all special regex characters will produce this problem.

Here an example:

  Scenario Outline: Parenthesis
    Given the thing <is (not) triggered> and has <value>

    Examples: Thing
      | is (not) triggered | value |
      | is triggered       | foo   |
      | is not triggered   | bar   |
      | is triggered       | baz   |

Expected Behavior

The variable should be replaced properly. It works in the python behave package.

Current Behavior

The variable does not get replaced.

Possible Solution

In the other issue we found out that https://github.com/cucumber/cucumber/blob/master/gherkin/javascript/src/pickles/compile.ts#L218 is probably the culprit. The variable name is used directly inside the search RegEx, but it should be be escaped before. See https://developer.mozilla.org/en-US/docs/Web/JavaScript/Guide/Regular_Expressions#Escaping

Your Environment

Versions:
Ubuntu 18.04.4 LTS
cucumber-js: 6.0.5
node: v10.20.1