In software engineering, a design pattern is a general, reusable solution to a commonly occurring problem within a given context in software design. It is not a finished design that can be transformed directly into source or machine code. Rather, it is a template for how to solve a problem that can be used in many different situations.

Few months ago, I read the book Selenium Design Patterns and Best Practices by author Dima Kovalenko. The author has explained various design patterns and best practices that can be used while working with Selenium Webdriver.

Design Patterns :

1. Spaghetti pattern:

It is one of the anti patterns.

Tests in this pattern depends on the execution order of all the tests. Each test is not self sufficient and independent, and thus needs previously run tests to set up the test environment.

Tight coupling is present among the tests

Disadvantages :

• Cannot run tests in parallel

• A test failed will halt execution of the following test cases

2. DRY pattern:

DRY stand for Don’t Repeat Yourself, a basic principle of software development aimed at reducing repetition of information. This principle is stated as, “Every piece of knowledge or logic must have a single, unambiguous representation within a system.”

Advantages :

• Modular tests

• Reduces duplicate code

• Faster code updates as the updation needs to be done at a single place

Disadvantages :

• Needs programming skills

• Constantly looking for places where this principle can be applied

3. Hermetic test pattern :

It states that each test should be completely independent and self-sufficient. Any dependency on other tests or third-party services that cannot be controlled should be avoided.

Advantages :

• Modular tests

• No tests skip in case any prior test fails

• Tests can be run in random order

• Can run tests in parallel

Disadvantages :

• Time required to write tests increases

• Runtime increases as env setup needs to be done before every test. *Designing of test cases take time as test can’t reuse data from other tests

4. Black Hole Proxy Pattern :

Modern web has many things like social networking buttons, images coming from CDNs, tracking pixels, analytics. All these items can destabilise our tests at any point. Black Hole Proxy takes all HTTP requests going to third-party websites and blocks them, as if the request was sucked into a black hole.

Advantages :

• It tries to reduce test instability by getting rid of as many third-party uncertainties as possible.

• It helps in reducing test execution time & in increasing test stability.

5. BDD pattern :

BDD (Behaviour Driven Development) is an agile testing methodology.

Advantages :

• It encourages collaboration between business users, developers and testers.

• At its heart, BDD has parameterisation and data tables built in.

• Feature files are written in Gherkin language which is quite simple to read & understand by everyone in the team

Disadvantages :

• Time Overhead

• Structuring all your feature files, scenarios and executable specifications requires some careful planning.

• Good communication is required between the person writing the feature files and the person developing the automation code

6. Page Object Model pattern :

Locatorsand their methods are separately written for each screen of the UI. Tests are allowed to use these methods, without worrying about the internal implementation.

Advantages :

• Code becomes modular

• Code becomes reusable (ex SigninPage methods are used in most of test classes)

• When any locator changes, refactoring is needed only in its page class

Disadvantages :

Complexity increases (framework needs to be created)

Time consuming

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