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SDLC Infographic

1️⃣ The "Golden Rule": Early Testing

Key Concept: Testing is an activity, not just a phase. If you wait until the code is finished to start testing, you are too late.

📉 The Cost of Fixing Defects

The later a bug is found, the more expensive it is to fix. This is known as the Cost of Change Curve.

Requirements $1
Cheap to fix text on paper
Development $10
Rewriting functions takes time
Production $100+
Hotfixes, lost trust, corruption
💡 Pro Tip: Your job as a tester isn't just to find bugs in the software; it's to find bugs in the ideas before they become software.

2️⃣ The Big Picture: SDLC & Testing Alignment

SDLC Phase Development Goal Tester's Role (Validation)
Requirements What are we building? Static Testing: Do these requirements make sense?
Design How will we build it? Logical Review: Does this flow handle errors?
Development Build the solution. Preparation: Writing test cases & data.
Testing Verify the solution. Execution: Running tests & reporting defects.
Deployment Release to users. Sanity Check: Is the release safe?
Maintenance Keep it running. Regression: Did we break anything old?

3️⃣ Phase 1: Requirements Analysis

The Goal: Ensure requirements are clear, complete, and testable.

🕵️‍♀️ Your Job (Static Testing)

You are reviewing documentation, not code. You are looking for Ambiguity.

  • Review & Walkthrough: Read the Business Requirement Document (BRD).
  • Identify Gaps: Ask "What happens if the user loses internet here?"
  • Define Acceptance Criteria: What exactly determines "Success"?

📌 Real World Example

❌ Bad Requirement ✅ Testable Requirement
"The page should load fast." "The page must load in under 2 seconds with 4G connection."
"The password should be strong." "The password must have 8+ characters, 1 number, and 1 symbol."

4️⃣ Phase 2: Design

The Goal: Ensure the technical design supports the business needs.

🕵️‍♀️ Your Job

You are the voice of the user during architectural discussions.

  • Design Review: Look at the wireframes or UI designs.
  • Data Flow Analysis: If a user saves data here, does it show up there?
  • Risk Analysis: Where is this feature most likely to break?
🧠 Critical Thinking: If the design shows a "Upload Photo" button, ask: "What is the maximum file size? What format? What happens if the file is corrupt?"

5️⃣ Phase 3: Development (Coding)

The Goal: Build the software.

🕵️‍♀️ Your Job (Preparation)

While developers are writing code, you are NOT idle. This is your busiest preparation time.

  1. Write Test Cases: Create the step-by-step instructions you will run later.
  2. Prepare Test Data: Create dummy users, fake credit card numbers, or sample files.
  3. Review Unit Tests: (Advanced) Check if developers have covered the basics.

6️⃣ Phase 4: The Testing Phase

The Goal: Validate the system end-to-end.

🕵️‍♀️ Your Job (Execution)

This is "Dynamic Testing"—running the software.

  • Smoke Testing: The "Health Check." Does the app launch? If no, reject the build.
  • Functional Testing: Testing specific features against requirements.
  • Regression Testing: Re-testing unchanged parts to ensure new code didn't break old code.
  • Bug Reporting: Logging clear, reproducible defects.

7️⃣ Phase 5: Deployment

Goal: Release safely.

  • Sanity Testing: A quick check in Staging/Production.
  • Release Verification: Confirm versioning.

⚠️ Warning: Never do "Destructive Testing" (like deleting data) in Production!

8️⃣ Phase 6: Maintenance

Goal: Stability & Evolution.

  • Regression Testing: Check patches.
  • Incident Analysis: Reproduce user bugs.

🔁 Summary Concept: Shift-Left Testing

Shift-Left simply means moving testing activities to the left side of the timeline (earlier in the SDLC).

Requirements ➔ Design ➔ Code ➔ TEST (Too Late!)
✅ TEST Req ➔ ✅ TEST Design ➔ ✅ TEST Code ➔ Verify

Benefits:
  1. Faster Feedback: Devs know about bugs immediately.
  2. Lower Cost: Preventing a bug is cheaper than fixing it.
  3. Better Quality: Quality is built in, not inspected in.

📝 Quick Quiz

(Self-reflection: Try to answer these before moving to the next module)

  1. Which phase is the most expensive to fix a bug in?
  2. What is the manual tester doing during the Development Phase?
  3. What is the difference between Smoke Testing and Regression Testing?
Last modified: Friday, 23 January 2026, 11:53 AM