Role Guides: Python for SDET, SDE, and SRE

In short: everyone learns the same core Python first. After that, each role uses Python for different jobs, so each role gets its own guide.

How to use this page

1. Find your role in the table below.
2. Finish the core language first (the cheat sheet or Python Fundamentals).
3. Then read your role's two guides in order: the main guide first, the advanced guide second.

The three roles

In short: the job title tells you what you mostly use Python for.

Role	Full name	What you mostly use Python for
SDET	Software Development Engineer in Test	Writing automated tests and test frameworks
SDE	Software Development Engineer	Building applications, services, and APIs
SRE	Site Reliability Engineer	Automating operations and keeping systems running

Which guide to read

Role	Start with	Then
SDET	Python for SDET	Advanced Python for SDET
SDE	Python for SDE	Advanced Python for SDE
SRE	Python for SRE	Advanced Python for SRE

The main guide shows how everyday Python (functions, classes, files, errors) applies to your role. The advanced guide covers the bigger topics you'll meet on the job.

Learning Java instead? SDETs start with Java for SDET after the Java learning path.

Working with databases? After the SQL learning path, SDETs read SQL for SDET.

What everyone learns first

In short: these topics are the same for every role. Learn them once, in this order, before moving to a role guide.

1. Setup — install Python, create a virtual environment, run a script.
2. Values & types — numbers, text, True/False, None.
3. Collections — list, tuple, set, dict, and when to use each.
4. Decisions & loops — if, for, while, comprehensions.
5. Functions — arguments, return values, small lambdas.
6. Classes — objects, dataclasses, inheritance.
7. Handling errors — try / except, raising your own errors.
8. Files & modules — reading and writing files, importing code.
9. Testing & logging — pytest, the logging module.
10. Type hints — describing what types your code expects.
11. Doing several things at once — threads, processes, and async.
12. Talking to web services — sending HTTP requests, building a small API.

The Learning Path turns this list into a week-by-week plan with a mini-project for each step.

What each role adds

In short: after the core, each role goes deeper on a different set of topics.

SDET — testing and automation

• Advanced pytest: fixtures (shared setup), parametrising (one test, many inputs)
• Mocking: replacing slow or external parts, like a real web service, with fakes
• Browser and API automation frameworks
• Running tests automatically on every code change (CI/CD — continuous integration / continuous delivery)
• Testing async code

SDE — building and shipping software

• Packaging your code so others can install it with pip
• Deployment: getting code safely onto servers
• Background jobs and message queues (e.g. Celery), for work that shouldn't make a user wait
• Database design
• Security basics: secrets, input checking, safe dependencies

SRE — running systems reliably

• Automating infrastructure and cloud tasks
• Kubernetes: the system that runs and restarts containers
• Monitoring: metrics, logs, and alerts
• Automating incident response (runbooks as scripts)
• Chaos testing: breaking things on purpose to prove the system recovers

How important each topic is, by role

In short: the same topic can be daily work for one role and occasional for another. Use this to decide what to learn first.

Topic	SDET	SDE	SRE
Advanced testing	Essential	Important	Useful
Mocking	Essential	Essential	Important
CI/CD	Essential	Important	Essential
Packaging	Useful	Essential	Useful
Deployment	Sometimes	Essential	Essential
Message queues	Important	Essential	Important
Security	Important	Essential	Essential
Infrastructure automation	Sometimes	Sometimes	Essential
Monitoring	Important	Important	Essential

Topics shared by all roles

A few advanced topics show up in every role once you work on real systems:

• Testing in production — checking a live system safely.
• Safe releases — rolling out to a few users first (a canary release) or switching between two identical environments (blue-green).
• Rolling back — undoing a bad release quickly.
• Performance testing — measuring speed under load before users notice.

Try it: pick your role, open its main guide, and skim the section headings. Tick off the ones you could already explain to a colleague — the rest is your study list.