Test environment is the is physically or logically isolated and distinct from the production environment . Sometimes, others want to have one environment for testing and production, for example, to save costs, resources or time. However, we have to always consider following benefits of having the separated test environment that allows to:
- analyze the changes separately from the production environment before the implementation in it, looking for impacts on security and business processes.
- ensure that activities in the test environment do not impact operational activities in the production environment and vice versa.
- eliminate unauthorized access to the production data.
Various international bodies recommends to separate test environment from the production environment, such as:
- National Institute of Standards and Technology (NIST) 
- International Organization for Standardization (ISO) 
- Information Systems Audit and Control Association (ISACA) 
- Center of Internet Security (CIS) 
- Open Security Architecture (OSA)
- https://linuxtogether.org/why-should-we-have-separate-development-testing-and-production-environments/ – Why should we have separate development, testing, and production environments?
- https://nvd.nist.gov/800-53/Rev4/control/CM-4 – NIST Special Publication 800-53 (Rev. 4), CM-4 SECURITY IMPACT ANALYSIS
- https://www.isms.online/iso-27001/annex-a-12-operations-security/ – ISO 27001 Annex A.12.1
- https://community.mis.temple.edu/mis5202online2018/files/2018/08/COBIT5-Enabling-English.pdf, BAI07 – COBIT Enabling Processes
- https://controls-assessment-specification.readthedocs.io/en/latest/control-18/control-18.9.html – CIS Control 18: Application Software Security » 18.9: Separate Production and Non-Production Systems
- https://www.opensecurityarchitecture.org/cms/library/0802control-catalogue/155-08-02-cm-04 – OSA, CM-04 Monitoring Configuration Changes