Tag Expressions¶

Tag-Expressions v2¶

Tag-Expressions v2 are based on cucumber-tag-expressions with some extensions:

Tag-Expressions v2 provide boolean logic expression (with and, or and not operators and parenthesis for grouping expressions)
Tag-Expressions v2 are far more readable and composable than Tag-Expressions v1
Some boolean-logic-expressions where not possible with Tag-Expressions v1
Therefore, Tag-Expressions v2 supersedes the old-style tag-expressions.

TAG-EXPRESSION EXAMPLES¶

# -- EXAMPLE 1: Select features/scenarios that have the tags: @a and @b
@a and @b

# -- EXAMPLE 2: Select features/scenarios that have the tag: @a or @b
@a or @b

# -- EXAMPLE 3: Select features/scenarios that do not have the tag: @a
not @a

# -- EXAMPLE 4: Select features/scenarios that have the tags: @a but not @b
@a and not @b

# -- EXAMPLE 5: Select features/scenarios that have the tags: (@a or @b) but not @c
# HINT: Boolean expressions can be grouped with parenthesis.
(@a or @b) and not @c

COMMAND-LINE EXAMPLE:

USING: Tag-Expressions v2 with behave¶

# -- SELECT-BY-TAG-EXPRESSION (with tag-expressions v2):
# Select all features / scenarios with both "@foo" and "@bar" tags.
$ behave --tags="@foo and @bar" features/

# -- EXAMPLE: Use default_tags from config-file "behave.ini".
# Use placeholder "{config.tags}" to refer to this tag-expression.
# HERE: config.tags = "not (@xfail or @not_implemented)"
$ behave --tags="(@foo or @bar) and {config.tags}" --tags-help
...
CURRENT TAG_EXPRESSION: ((foo or bar) and not (xfail or not_implemented))

# -- EXAMPLE: Uses Tag-Expression diagnostics with --tags-help option
$ behave --tags="(@foo and @bar) or @baz" --tags-help
$ behave --tags="(@foo and @bar) or @baz" --tags-help --verbose

Tag Matching with Tag-Expressions¶

Tag-Expressions v2 support partial string/tag matching with wildcards. This supports tag-expressions:

Tag Matching Idiom	Example 1	Example 2	Description
`tag.starts_with`	`@foo.*`	`foo.*`	Search for tags that start with a `prefix`.
`tag.ends_with`	`@*.one`	`*.one`	Search for tags that end with a `suffix`.
`tag.contains`	`@foo`	`foo`	Search for tags that contain a `part`.

FILE: features/one.feature¶

Feature: Alice

  @foo.one
  Scenario: Alice.1
    ...

  @foo.two
  Scenario: Alice.2
    ...

  @bar
  Scenario: Alice.3
    ...

The following command-line will select all features / scenarios with tags that start with “@foo.”:

USAGE EXAMPLE: Run behave with tag-matching expressions¶

$ behave -f plain --tags="@foo.*" features/one.feature
Feature: Alice

  Scenario: Alice.1
    ...

  Scenario: Alice.2
    ...

# -- HINT: Only Alice.1 and Alice.2 are matched (not: Alice.3).

Note

Filename matching wildcards are supported. See fnmatch (Unix style filename matching).
The tag matching functionality is an extension to cucumber-tag-expressions.

Select the Tag-Expression Version to Use¶

The tag-expression version, that should be used by behave, can be specified in the behave config-file.

This allows a user to select:

Tag-Expressions v1 (if needed)
Tag-Expressions v2 when it is feasible

EXAMPLE:

FILE: behave.ini¶

# SPECIFY WHICH TAG-EXPRESSION-PROTOCOL SHOULD BE USED:
#   SUPPORTED VALUES: v1, v2, auto_detect
#   CURRENT DEFAULT:  auto_detect
[behave]
tag_expression_protocol = v1    # -- Use Tag-Expressions v1.

Tag-Expressions v1¶

Tag-Expressions v1 are becoming deprecated (but are currently still supported). Use Tag-Expressions v2 instead.

Note

Tag-Expressions v1 support will be dropped in behave v1.4.0.