Types of Testing

Acceptance testing

This type of testing is done to determine if a feature or system meets the customer expectations and requirements. This type of testing generally involves the customer’s cooperation or feedback, being a validation activity that answers the question:

Are we building the right product?

For web applications, the automation of this testing can be done directly with Selenium by simulating user expected behaviour. This simulation could be done by record/playback or through the different supported languages as explained in this documentation. Note: Acceptance testing is a subtype of functional testing, which some people might also refer to.

Functional testing

This type of testing is done to determine if a feature or system functions properly without issues. It checks the system at different levels to ensure that all scenarios are covered and that the system does what it’s supposed to do. It’s a verification activity that answers the question:

Are we building the product right?

This generally includes: the tests work without errors (404, exceptions…), in a usable way (correct redirections),
in an accessible way and matching its specifications (see acceptance testing above).

For web applications, the automation of this testing can be done directly with Selenium by simulating expected returns.
This simulation could be done by record/playback or through the different supported languages as explained in this documentation.

Performance testing

As its name indicates, performance tests are done to measure how well an application is performing.

There are two main sub-types for performance testing:

Load testing

Load testing is done to verify how well the application works under different defined loads (usually a particular number of users connected at once).

Stress testing

Stress testing is done to verify how well the application works under stress (or above the maximum supported load).

Generally, performance tests are done by executing some Selenium written tests simulating different users hitting a particular function on the web app and retrieving some meaningful measurements.

This is generally done by other tools that retrieve the metrics. One such tool is JMeter.

For a web application, details to measure include throughput, latency, data loss, individual component loading times…

Note 1: All browsers have a performance tab in their developers’ tools section (accessible by pressing F12)

Note 2: is a subtype of non-functional testing as this is generally measured per system and not per function/feature.

Regression testing

This testing is generally done after a change, fix or feature addition.

To ensure that the change has not broken any of the existing functionality, some already executed tests are executed again.

The set of re-executed tests can be full or partial and can include several different types, depending on the application and development team.

Test driven development (TDD)

Rather than a test type per se, TDD is an iterative development methodology in which tests drive the design of a feature.

Each cycle starts by creating a set of unit tests that the feature should eventually pass (they should fail their first time executed).

After this, development takes place to make the tests pass. The tests are executed again, starting another cycle and this process continues until all tests are passing.

This aims to speed up the development of an application based on the fact that defects are less costly the earlier they are found.

Behavior-driven development (BDD)

BDD is also an iterative development methodology based on the above TDD, in which the goal is to involve all the parties in the development of an application.

Each cycle starts by creating some specifications (which should fail). Then create the failing unit tests (which should also fail) and then do the development.

This cycle is repeated until all types of tests are passing.

In order to do so, a specification language is used. It should be understandable by all parties and simple, standard and explicit. Most tools use Gherkin as this language.

The goal is to be able to detect even more errors than TDD, by targeting potential acceptance errors too and make communication between parties smoother.

A set of tools are currently available to write the specifications and match them with code functions, such as Cucumber or SpecFlow.

A set of tools are built on top of Selenium to make this process even faster by directly transforming the BDD specifications into executable code. Some of these are JBehave, Capybara and Robot Framework.