Maxi ContieriDon't add IFs checking for production environment.
TL;DR: Avoid adding conditionals related to production
Problems
Fail fast principle violation
Lack of testability
Solutions
- If completely necessary, model environments and test ALL of them.
Context
Sometimes, We need to create different behaviors in development and production.
For example the passwords strength.
In this case, we need to configure the environment with the strength strategy and test the strategy and not the environment itself.
Sample Code
Wrong
def send_welcome_email(email_address, environment):
if ENVIRONMENT_NAME == "production":
print(f"Sending welcome email to {email_address} from Bob Builder <bob@builder.com>")
else:
print("Emails are sent only on production")
send_welcome_email("john@doe.com", "development")
# Emails are sent only on production
send_welcome_email("john@doe.com", "production")
# Sending welcome email to john@doe.com from Bob Builder <bob@builder.com>
Right
class ProductionEnvironment:
FROM_EMAIL = "Bob Builder <bob@builder.com>"
class DevelopmentEnvironment:
FROM_EMAIL = "Bob Builder Development <bob@builder.com>"
#We can unit test environments
#and even implement different sending mechanisms
def send_welcome_email(email_address, environment):
print(f"Sending welcome email to {email_address} from {environment.FROM_EMAIL}")
#We can delegate into a fake sender (and possible logger)
#and unit test it
send_welcome_email("john@doe.com", DevelopmentEnvironment())
# Sending welcome email to john@doe.com from Bob Builder Development <bob@builder.com>
send_welcome_email("john@doe.com", ProductionEnvironment())
# Sending welcome email to john@doe.com from Bob Builder <bob@builder.com>
Detection
[X] Manual
This is a design smell.
We need to create empty development/production configurations and delegate with customizable polymorphic objects.
Tags
- Coupling
Conclusion
Avoid adding untestable conditionals.
Create configurations delegating business rules.
Use abstractions, protocol and interfaces, avoid hard hierarchies.
Relations
More Info
Credits
Photo by Birmingham Museums Trust on Unsplash
This tweet was inspired by @jangiacomelli
Complexity is a sign of technical immaturity. Simplicity of use is the real sign of a well design product whether it is an ATM or a Patriot missile.
Daniel T. Ling
This article is part of the CodeSmell Series.
