Designing Acceptance Tests

Test Techniques for Acceptance Testing 

In a requirements-based approach to acceptance testing, the tester derives test cases from the acceptance criteria related to each requirement or user story using black-box techniques such as equivalence partitioning or boundary value analysis

Acceptance testing may be augmented with other test techniques or approaches:

• Business process-based testing, possibly combined with decision table testing, validates business processes and rules
• Experience-based testing leverages the tester’s experience, knowledge and intuition  
  
• Risk-based testing is based on risk types and levels. Prioritization and thoroughness of testing depends on previously identified product risks.
• Model-based testing uses graphical (or textual) models to obtain acceptance tests
  

Acceptance criteria should be verified by acceptance tests and traceability between the requirements / user story and related test cases should be managed.

Exploratory testing is an experience-based test technique that is not based on detailed predefined test procedures. The testers are domain experts. They are familiar with user needs, requirements and business processes, but they are not necessarily familiar with the product under test.

During an exploratory testing session, the tester accomplishes the following:

• Learns how to work with the product
• Designs the tests
• Performs the tests
• Interprets the results

It is a good practice in exploratory testing to use a test charter. The test charter is prepared prior to the testing session (possibly jointly by the business analyst and the tester) and is used by the person in charge of the exploratory session (either a business analyst, tester or another stakeholder). It includes information about the purpose, target, and scope of the exploratory session, the test setup, the duration of the session, and possibly some tactics to be used during the session (such as the type of user that shall be simulated during the exploratory session). Time-boxed sessions help to control the time and effort dedicated to the exploratory session. It is also good practice to perform exploratory testing in pairs or as team work.

In Agile development, exploratory test sessions can be conducted during an iteration by the product owner and/or the testers for acceptance testing of user stories assigned to the iteration.

Exploratory testing should be used to complement other more formal techniques in acceptance testing. For example, it may be used to provide rapid feedback on new features before methodical testing is applied.

Using the Gherkin Language to Write Test Cases

In ATDD and BDD, acceptance tests are often formulated in a structured language, referred to as the Gherkin language. Using the Gherkin language, test cases are phrased declaratively using a standardized pattern:

• Given [a situation]
• When [an action on the system]
• Then [the expected result]

The pattern allows business analysts, testers and developers to write test cases in a way that is easily shared with stakeholders and may be translated into automated tests.

The “Given” block aims to put the test object in a state before performing test actions in the “When” block. The "Then" block specifies the consequences that can be observed from the actions defined in the "When" block. Test cases written in Gherkin do not refer to user interface elements but rather to user actions on the system. They are structured natural language test cases that can be understood by all relevant stakeholders.

In addition, the structure “Given – When – Then” can be parsed in an automated way.

This allows automated test script creation using a keyword-driven testing approach.

Initially, Gherkin was specific to some software tools supporting BDD, but it is now synonymous with the “Given – When – Then” acceptance test design pattern.