Stop 01 · QA & Software Testing FoundationsTopics · 5/9

Testing in the SDLC

In short

If testing only starts after all the code is written, bugs pile up and fixes get expensive. Testing belongs in every stage of building software.

Understanding where testing fits into the broader Software Development Life Cycle — from requirements through design, development, testing, deployment, and maintenance — and how 'shift-left' has moved testing earlier.

The purple blob in a hard hat checks a half-built brick wall with a spirit level.

Think of it like this

Building a house

A good builder checks the plan, then the foundation, then the walls, then the wiring, before handing over the keys. Finding a crooked wall after painting means breaking and redoing it. Software is the same.

Watch it happen

What QA does at each SDLC stage

Requirements

Design

Development

Testing

Deployment

Maintenance

1/6QA reviews requirements for gaps and starts thinking about how each one will be checked.

The big ideas

What you need to know

Later bugs cost more

A wrong requirement fixed in a meeting takes minutes. The same mistake found in production may need code, data fixes and apologies.

The V-model pairs them

In the V-model, each build stage has a matching test level: requirements to acceptance tests, design to integration, code to unit tests.

Shift left

Moving testing activities earlier in the SDLC is called shift-left testing. You'll study it in detail later.

Save yourself the pain

Common mistakes

Oops

Seeing QA as a gate that only opens after development ends.

Do this instead

Involve QA from requirements onwards. Early questions are the cheapest bug fixes you'll ever get.

Oops

Assuming testing is finished once the app is released.

Do this instead

Production smoke tests, bug reproduction and new regression tests continue for as long as the app lives.

Your mission

Map one bug to the stage it came from

~15 min

Quick check

A signup form doesn't say what happens if the email is already registered. When is the cheapest time to catch this?

Go deeper

1Diagram the SDLC and mark where testing traditionally happens versus where shift-left moves it.
2Learn why testing solely at the end of the SDLC is now considered a legacy, riskier approach.
3Understand modern QA is embedded throughout delivery, not a separate final gate.