Cucumber Tag Expressions

Readable boolean expressions to select features and scenarios marked with tags in Gherkin

# -- SIMPLE TAG-EXPRESSION EXAMPLES:
@a and @b
@a or @b
not @a

# -- MORE TAG-EXPRESSION EXAMPLES:
@a and not @b
(@a or @b) and not @c

Getting Started

Cucumber Tag Expressions is available as cucumber-tag-expressions on PyPI.

pip install cucumber-tag-expressions

Parse tag expressions and evaluate them against a set of tags.

>>> from cucumber_tag_expressions import parse

# Tagged with @fast
>>> fast = parse("@fast")
>>> fast({"@fast", "@wip"})
True
>>> fast({"@performance", "@slow"})
False

# Tagged with @wip and not @slow
>>> wip_not_slow = parse("@wip and not @slow")
>>> wip_not_slow({"@wip", "@home"})
True
>>> wip_not_slow({"wet", "warm", "raining"})
False

# Tagged with both `@fast` and `@integration`
>>> fast_integration = parse("@integration and @fast")
>>> fast_integration({"@integration", "@fast", "@other"})
True
>>> fast_integration({"@system", "@fast"})
False

# Tagged with either @login or @registration
>>> auth_pages = parse("@login or @registration")
>>> auth_pages({"@account", "@login"})
True
>>> auth_pages({"@admin", "@account"})
False

Test Runner Usage

A gherkin test runner (such as behave) uses tag expressions to select scenarios to run.

# -- TAG-EXPRESSION: @one and @two
# EXPECTED: Selects and runs scenario "Three".
$ my_cucumber_test_runner --tags="@one and @two" features/example.feature
...

# -- TAG-EXPRESSION: @one or @two
# EXPECTED: Selects and runs scenarios "One", "Two" and "Three".
$ my_cucumber_test_runner --tags="@one or @two" features/example.feature
...

Such as using the following feature file.

# -- FILE: features/example.feature
Feature: Tag expressions example

  @one
  Scenario: One
    Given a step passes

  @two
  Scenario: Two
    Given another step passes

  @one @two
  Scenario: Three
    Given some step passes

  Scenario: Four
    Given another step passes