Getting started with selenium-grid
What is Selenium Grid?
Selenium-Grid is a configuration of Hub & Node which allows you to run your tests on different machines against different browser combinations in parallel. That is, running multiple tests at the same time against different machines running different browsers on different operating systems. In other words Selenium Grid supports running the tests in Distributed Environment.
When to use it
- To run your tests against multiple browsers, multiple versions of browser, and browsers running on different operating systems. This will ensure that the application you are testing is fully compatible with a wide range of browser-O.S combinations.
- To reduce the time it takes for the test suite to complete a test pass. Lets say you setup your Grid to run 8 tests at a time, your execution would finish 8 times faster as compared to your normal run.
Selenium-Grid is used to speed up the execution of a test by using multiple machines to run tests in parallel.
What is a Hub & Node?
- The Hub is the main engine/central point of the entire configuration, point where all the nodes are connected.
- Hub should run only on a single machine.
- There should only be 1 hub running where all the tests are loaded.
- Tests will be run on the machines where hub is running, but you can see the browsers on the node machines.
- Nodes are the instances (machines) which will execute the tests that are loaded on the hub.
- There are no limitations on Node machines, a user can setup n number of Nodes.
- Nodes can be launched on different machines with different OS and browser combinations.
- Machines running the nodes can be of different/same configurations as of Hub Machine.