ISTQB Technical Test Analyst (CTAL-TTA v4.0) Skill

ISTQB Technical Test Analyst (CTAL-TTA v4.0) Skill

Knowledge Areas

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Quick Decision Trees

Which White-Box Technique?

Is the system safety-critical (aerospace, automotive, medical)?
├── YES → Check IEC 61508 SIL level:
│         SIL 1 → Statement + Branch coverage
│         SIL 2 → Branch coverage
│         SIL 3 → MC/​DC (recommended)
│         SIL 4 → MC/​DC (highly recommended)
└── NO  → Check applicable factors:
          Contract/​regulatory requirement? → Use required technique
          Complex boolean conditions?      → MC/​DC or Multiple Condition
          Simple control flow?             → Decision/​Branch coverage
          Minimum baseline needed?         → Statement coverage
          All condition combos needed?     → Multiple Condition (2^N)

Coverage Subsumption Hierarchy

Multiple Condition Testing  (strongest — 2^N combinations)
         ↑ subsumes
    MC/​DC Testing           (N+1 minimum tests)
         ↑ subsumes
   Decision/​Branch Testing  (all TRUE/​FALSE outcomes)
         ↑ subsumes
   Statement Testing        (weakest — baseline only)

Higher coverage subsumes all lower levels. Choose the lowest level that satisfies your risk/​safety requirement.

Which Quality Characteristic Test?

Does the threat involve unauthorized access or data breach?  → security-testing
Is the concern about system uptime, MTBF, failover?         → reliability-testing
Is the concern about response time, throughput, or load?    → performance-testing
Is the concern about code structure, coupling, modifiability?→ maintainability-testing
Is the concern about install, run on multiple platforms?    → portability-testing
Is the concern about shared environment, resource conflicts? → compatibility-testing

Non-Functional Test Planning

1. Identify quality characteristics from stakeholder requirements
2. Benchmark existing system (if available)
3. Plan production-like test environment
4. Acquire specialized tools
5. Address data security/​privacy constraints
6. Write test specifications using operational profiles

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Common Patterns

Operational Profile Usage

• Define user types and frequency of operations
• Generate pseudo-random test inputs weighted by usage frequency
• Apply to both reliability testing (MTBF estimation) and performance testing (realistic load)
• Tools can automate test case generation from profiles

Risk-Based Technique Selection

• High technical risk (complex logic, high change rate, defect history) → stronger coverage technique
• TTA contributes probability assessment; TA contributes business impact assessment
• Risk level determines minimum coverage target and technique selection

MC/​DC Minimum Test Count

• N unique atomic conditions → minimum N+1 test cases
• Each condition must independently affect the decision outcome
• Watch for short-circuit evaluation (compiler may not evaluate all conditions)

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Anti-Patterns

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Rule Reference Index