Friday, May 6, 2016

Design patterns in QA Automation - PoC




    Following the example of Anton Angelov's "Design Patterns in Automation Testing" Series, I have  put together some of the PoC projects that I have prepared in the past. Some of the patterns were purely for the fun of learning, others did convince the team in their benefits and actually made it to the Big league projects. Many of the patterns in this list were introduced in a refactorings of existing Automation solutions, so we had to double check the value which they would bring to the Project in a real-life and everyday usage.
    Here is the list of the patterns I have managed to re-create again:

  •  Blackboard
Building a software system for WebElements' image recognition.
Input is screenshot recorded as image and output is accessible WebElement.
  • ChainOfResponsibility
Using this pattern we encapsulates the test steps inside a "pipeline" abstraction 
and have scripts "launch and leave" their requests at the entrance of the pipeline.
  • Composite
Helps us to create Page Objects by forming a tree structure and ask each node in the tree structure to perform a task (loading, verifing itself). 
  • Flyweight
  • Interpreter
Can be used as rules engine to support business logic in tests or on creation of their fixtures.
  • LazyInitialization
Provides delayed execution of certain tasks. Good example is a Shared fixture scenario or 
DB sandboxing.
  • Mediator
Since it encapsulates how a set of objects interact, we can use it to share test execution data
and analysis between Reporting systems.
  • Module
Extensibility modules let us consolidate our plug-ins into a centralized place. Good fit for this case
are the different Reporting systems we use.
  • Multiton
Helps us to manage a map of named instances as key-value pairs. Also simplifies retrieval 
of shared objects (fixtures).
  • ObjectPool
Uses a set of initialized objects kept ready to use, rather than allocating and destroying them on demand. 
Such expensive objects could be our test fixtures which we would like to re-use, but only one at a time 
between multiple parallel tests.
  • Observer
Since it define a one-to-many dependency between objects so that when one (test) object changes state,
all its dependents are notified and updated automatically. Good fit are the Reporting systems 
that needs to be notified of test's status.
  • PageLoader
Encapsilates navigation logic over site's pages via Bidirected and  Cyclic graph.
  • RAII  
By holding a resource tied to object lifetime, we can destroy all of them at the end. Good examples are Transaction roll-back and DB cleaning.
  • Servant  
Shared code for a group of classes, that appears in only one class without defining that functionality in each of them. Typical example is REST RequestSender that takes care of the multiple Contracts between the APIs.
  • State
Allow an object (fixtures) to alter its behavior when its internal state changes, so our tests could make use of it.

    The implementations are mainly focused and do represent Automation testing perspective. A good example is the Observer  pattern used to show how we could notify different systems for the test run output results. 

    You can find the GitHub repo here...

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