About @cucumber/tag-expressions
The "@cucumber/tag-expressions" npm package is a powerful tool designed for developers who use the Cucumber testing framework. This node module simplifies the management of tag expressions used in Cucumber to select specific scenarios for execution based on their tagged attributes. The primary purpose of the "@cucumber/tag-expressions" package is to provide a robust parser that interprets complex expressions involving tags, allowing for more flexible and targeted testing strategies. It supports logical operators such as "and", "or", and "not", enabling testers to create comprehensive expressions that precisely define which tests to run. This capability significantly enhances test suite management, making it easier to execute targeted tests that align with specific testing goals or requirements.
To start using "@cucumber/tag-expressions" in your project, you can simply run the command `npm install @cucumber/tag-expressions` in your terminal. This command installs the package and integrates it seamlessly with your existing Cucumber setup. Once installed, the package allows for the evaluation of tag expressions directly within your test environment, streamlining the process of scenario selection based on predefined criteria. By using "@cucumber/tag-expressions", developers can avoid manual filtering of scenarios, automate their testing workflows more effectively, and ensure that only relevant tests are executed during the development cycle. This not only saves time but also increases the efficiency of the testing process.
The benefits of integrating "@cucumber/tag-expressions" into your development workflow are substantial. It reduces the complexity of managing large test suites and helps maintain a high level of accuracy in testing outcomes. With its intuitive syntax and powerful parsing capabilities, "@cucumber/tag-expressions" makes it easier for teams to implement sophisticated testing frameworks that can handle complex requirements and scenarios. This npm package is an essential tool for any team looking to optimize their use of Cucumber and enhance their overall testing efficiency.
Documentation
A README file for the @cucumber/tag-expressions code repository. View Code
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:
- Run a subset of scenarios (using the
--tags expressionoption of the command line) - 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)" |