isabella232 / tag-expressions

Cucumber tag expression parser

Tag Expressions

Tag Expressions is a simple query language for tags. The simplest tag expression is simply a single tag, for example:

@smoke

A slightly more elaborate expression may combine tags, for example:

@smoke and not @ui

Tag Expressions are used for two purposes:

1. Run a subset of scenarios (using the --tags expression option of the command line)
2. Specify that a hook should only run for a subset of scenarios (using conditional hooks)

Tag Expressions are boolean expressions of tags with the logical operators and, or and not.

For more complex Tag Expressions you can use parenthesis for clarity, or to change operator precedence:

(@smoke or @ui) and (not @slow)

Escaping

If you need to use one of the reserved characters (, ), \ or (whitespace) in a tag, you can escape it with a \. Examples:

Gherkin Tag	Escaped Tag Expression
@x(y)	@x\(y\)
@x\y	@x\\y

Migrating from old style tags

Older versions of Cucumber used a different syntax for tags. The list below provides some examples illustrating how to migrate to tag expressions.

Old style command line	Cucumber Expressions style command line
--tags @dev	--tags @dev
--tags ~@dev	--tags "not @dev"
--tags @foo,@bar	--tags "@foo or @bar"
--tags @foo --tags @bar	--tags "@foo and bar"
--tags ~@foo --tags @bar,@zap	--tags "not @foo and (@bar or @zap)"