003: The Data Collector

The “Data Collector” code smell occurs within your “Given” steps in Gherkin scenarios. It’s related to the use of the Builder pattern, where you set the values of fields incrementally across multiple steps. By passing data piece by piece, this pattern leads to long scripts with individual steps for each field.

Impact

Harder Maintenance

Any change to the domain object requires updating multiple steps.

Increased Complexity

Readers must follow a sequence of steps to understand the complete data setup.

Increased Coupling

The coupling between scenarios and step implementation increases, especially when the order of steps matters. Changes in one step may ripple through others, affecting the entire scenario.

Inconsistent Data

The user of the scenarion must not omit any mandatory Given steps. If all required steps are not executed, it may result in inconsistent or uninitialized data.

Increased Script Length

The scenario becomes verbose due to numerous steps dedicated to setting field values.

Required Action

Replace multiple Given steps with a single step that passes the entire data object (from the same domain) at once. If required introduce a new step that initializes a domain object with all parameters required in a single step.

Code Examples

Gherkin

Customer.feature

Scenario: Should successfully create new customer
    Given the customer first name is "Max"
    And the customer last name is "Mustermann"
# (1)!
    When the customer is created
    Then the customer creation should be successful

The data for a customer is collected in two different steps. Merge the steps to pass the data at once instead.