🧩Test Design & Analysis – Turning Requirements into Test Cases

Welcome back to The QA Vibe! In this chapter, we’re diving deep into one of the most critical phases of testing — transforming requirements into meaningful, executable test cases. If test planning sets the stage, test design delivers the performance.

🧠 What Is Test Design & Why It Matters

Test design is the art of creating a blueprint for validating whether a system behaves as expected. It bridges the gap between "what should happen" (requirements) and "what we actually check" (test cases).

A well-designed test case does more than just catch bugs — it ensures that we’re testing the right things, in the right way, at the right time.

📍 In an HR platform I worked on, poor test design led to missed validation on employee shift patterns. After redesigning our test cases with real user scenarios, we caught 3 major logic issues before release.

🔍 Analyzing Requirements Before You Test

Before you write a single test case, you must understand what you're testing — and that starts with requirement analysis.

Key things to look for:

• Are the requirements clear, complete, and testable?

• Are there any ambiguities or assumptions?

• Can you map the requirement to specific actions or validations?

📍 In a yard management solution, a vague requirement like “optimize vehicle queue” wasn’t testable until we worked with BAs to define what “optimize” meant: reduced wait time, first-in-first-out logic, and time slot accuracy.

🧪 Test Design Techniques

In software testing, designing test cases effectively is crucial for uncovering defects and validating system behavior. The diagram below summarizes the three primary categories of test design techniques:

1. Black Box Test Design

Focus: Functionality of the software without looking at internal code.
Testers design test cases based on input/output behavior.

Key Techniques:

• Equivalence Partitioning: Divide input data into valid and invalid partitions and test one from each.

• Boundary Value Analysis: Test the edges of input ranges (e.g., min/max values).

• Decision Table Testing: Use tables to model complex business rules.

📌 Example: Testing a login form with correct and incorrect credentials without knowing how the authentication is coded.

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2. White Box Test Design

Focus: Internal structure and logic of the code.
Typically used by developers or automation testers.

Key Techniques:

• Statement Coverage: Ensure every line of code is executed at least once.

• Branch Coverage: Ensure each decision (e.g., if/else) is evaluated both ways.

• Path Coverage: Ensure all possible code paths are tested.

📌 Example: Testing that every conditional and loop in a function executes with specific data inputs.

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3. Experience-Based Test Design

Focus: Tester’s domain knowledge and intuition.
Ideal when documentation is limited or time is tight.

Key Techniques:

• Error Guessing: Based on experience, guess where the system might fail.

• Exploratory Testing: Simultaneously learning, designing, and executing tests.

• Checklist-Based Testing: Use predefined checklists to ensure consistent coverage.

📌 Example: While testing a finance app, a tester may guess that entering a negative number in a balance field could cause a crash — even if not documented.

Let’s break down a few core techniques testers use to write effective test cases:

✅ Equivalence Partitioning

Group inputs that are expected to be treated the same.
🧾 Example: For a field that accepts 1–100, test one value from within the range (e.g., 50), and one outside (e.g., 0 or 101).

✅ Boundary Value Analysis

Focus on the values at the edges — this is where bugs often hide.
🧾 In a student grading app, we tested 74, 75, and 76 to confirm grade boundaries (C to B).

✅ Decision Table Testing

Used when multiple conditions and rules apply.
🧾 In a payroll system, we built decision tables to test salary calculations with various combinations of tax, bonus, and leave deductions.

✅ State Transition Testing

Great for apps with workflows or user states.
🧾 In a school admin system, we mapped test cases for a student’s lifecycle: enrolled → active → suspended → graduated.

✅ Use Case Testing

Based on real user interactions and journeys.
🧾 For an HR portal, we tested the entire “Apply Leave” process as a single test case: from request → approval → calendar update.

✅ Error Guessing

Based on intuition and experience.
🧾 We guessed a login form might fail if someone used special characters in a username — and we were right!

🛠️ Domain-Specific Test Design Examples

📦 Yard Management:

• Tested GPS-based tracking with mock truck movements

• Designed test cases for rerouting when bays were full

💸 Finance:

• Tested edge cases in interest rounding and loan maturity

• Validated decimal precision in currency conversions

🎓 Education:

• Designed calendar tests for overlapping exam dates

• Tested score inputs with boundary values for pass/fail

👩‍💼 Employee Tools:

• Designed access control tests across roles (Employee, HR, Admin)

• Tested workflows like onboarding, leave approval, and resignation

✍️ Writing Strong, Maintainable Test Cases

Tips to keep your test cases clean and scalable:

• One test case = one goal

• Keep preconditions and steps clear

• Use consistent language and formats

• Include expected results — not just “it works”

• Prioritize by risk, business impact, and frequency of use

• Maintain traceability back to requirements (especially in tools like TestRail or Jira)

📍 I usually design with a mix of high-risk and high-use scenarios first. In one finance project, 20% of our test cases covered 80% of user actions.

⚠️ Common Mistakes to Avoid

• Writing overly broad test cases

• Skipping boundary and negative tests

• Testing only “happy paths”

• Not reviewing requirements with stakeholders

• Creating duplicate or redundant scenarios

• Ignoring user roles and permissions

💬 Final Thoughts

Test design isn’t just about filling in a test case template — it’s about thinking critically, understanding users, predicting risks, and making sure the system delivers value. The better the test design, the better the quality coverage.

🔜 Up Next in The QA Vibe:

Chapter 5: Managing Test Activities – Planning, Monitoring & Reporting
We’ll go behind the scenes of QA management: how to plan a test cycle, track progress, report bugs effectively, and close sprints confidently.