The second phase of creating a production deployment focuses on testing. This phase is important, because it enables you to identify any changes to the environment or configuration that must be completed before you deploy into production.
You use a test environment to test the deployment to ensure that it meets the requirements of the production deployment. The test environment should match the production environment as closely as possible. In the test environment, perform comprehensive testing of the deployment against the final requirements with a selection of the users and a sample data set.