Cucumber is a tool that executes plain-text functional descriptions as automated tests. The language that Cucumber understands is called Gherkin. Here is an example:
Feature: Search courses In order to ensure better utilization of courses Potential students should be able to search for courses Scenario: Search by topic Given there are 240 courses which do not have the topic "biology" And there are 2 courses A001, B205 that each have "biology" as one of the topics When I search for "biology" Then I should see the following courses: | Course code | | A001 | | B205 |
While Cucumber can be thought of as a “testing” tool, the intent of the tool is to support BDD. This means that the “tests” (plain text feature descriptions with scenarios) are typically written before anything else and verified by business analysts, domain experts, etc. non technical stakeholders. The production code is then written outside-in, to make the stories pass.