CTFL Chapter 4
Test Techniques Deep-Dive
Chapter 4 is the most important exam chapter for junior testers. Every technique has K3 learning objectives — you must be able to apply them, not just recall them.
What junior testers must master for CTFL
The CTFL exam expects you to apply test techniques to scenarios. The most commonly examined areas are:
- Identify equivalence partitions from a specification
- Apply 2-value and 3-value BVA to boundary conditions
- Build a decision table from business rules
- Achieve all-transition coverage on a state diagram
- Distinguish between experience-based techniques
Chapter 4 applied — technique cheat sheet
| Partition | EP representative | BVA boundary values | Expected |
|---|---|---|---|
| Below minimum | 10 | 17 (below), 18 (at min) | Rejected / Accepted |
| Valid range | 40 | 18 (min), 19 (above min), 64 (below max), 65 (max) | Accepted |
| Above maximum | 80 | 65 (at max), 66 (above) | Accepted / Rejected |
| Condition / Action | Rule 1 | Rule 2 | Rule 3 | Rule 4 |
|---|---|---|---|---|
| Valid username? | Y | Y | N | N |
| Valid password? | Y | N | Y | N |
| Logged in? | Yes | No | No | No |
| Error shown? | No | Yes | Yes | Yes |
Practice questions
These are CTFL-style questions. Answer them before checking the key.
Q1. A booking system accepts passengers aged 12–75 with a 2-value BVA approach. Which test inputs cover all boundaries?
A) 10, 12, 75, 76 B) 11, 12, 75, 76 C) 12, 13, 74, 75 D) 12, 75
Q2. You have 3 boolean conditions in a decision table. How many rules (columns) does the full table have?
A) 3 B) 6 C) 8 D) 9
Q3. State transition testing that exercises every valid transition at least once achieves which coverage level?
A) 0-switch B) 1-switch C) 2-switch D) All-state
Q4. A use case has a basic flow, two alternate flows, and one exception flow. Which flow should be tested FIRST and why?
A) Exception flow — errors are most likely to contain bugs B) Basic flow — it is the most common path and if it fails nothing else matters C) Alternate flows — they cover more scenarios D) All flows simultaneously using combinatorial testing
Q5. A tester writes: “Explore the registration form using invalid email formats to discover how the system handles malformed input.” What testing approach does this describe?
A) Regression testing B) Decision table testing C) Exploratory testing with a charter D) Ad hoc testing
Q6. A system has states: Locked, Unlocked, Alarm. From Locked, entering the correct PIN → Unlocked. From Locked, entering wrong PIN 3× → Alarm. From Alarm, admin reset → Locked. How many transitions must be covered for all-transitions (1-switch) coverage?
A) 3 B) 4 C) 5 D) 6
Q7 (NZ scenario). A tester is checking a New Zealand address form. The postcode field accepts exactly 4 digits (NZ postcodes are 4 digits). Using equivalence partitioning, which THREE partitions should she test?
A) Valid 4-digit NZ postcode / fewer than 4 digits / more than 4 digits B) Valid postcode / invalid postcode C) Numbers only / letters only D) Empty / filled
Answer key: Q1: B (just below the lower boundary = 11, then 12, 75, then just above = 76). Q2: C (2^3 = 8). Q3: B (all transitions = 1-switch coverage). Q4: B (the basic flow is tested first — if the core happy path is broken, alternate and exception flows cannot be meaningfully tested). Q5: C (this is an exploratory testing charter: Explore [target] using [approach] to discover [information] — with a time box it becomes a formal session). Q6: A (3 transitions exist: Locked→Unlocked, Locked→Alarm, Alarm→Locked; all-transitions coverage requires each transition executed once). Q7: A (EP identifies three partitions: valid 4-digit codes, codes with fewer digits, codes with more digits — one representative from each. This covers the valid partition and both invalid boundary partitions).
Exam tips specific to Chapter 4
- BVA always uses the same partition boundaries as EP — define EP first, then apply BVA to the partition edges.
- Invalid partitions matter — the exam always tests both valid AND invalid partitions. Don’t skip them.
- 3-value BVA = 3 values per boundary — for a range of 18–65, the lower boundary test set is 17, 18, 19 (not just 17 and 18).
- Decision tables: 2N columns for N binary conditions, before merging.
- Exploratory testing is NOT unstructured — know the charter + time box + session report structure.
After CTFL — the next step
CTFL qualifies you for junior and mid-level QA roles. The natural progression:
- 1–2 years experience applying CTFL techniques
- CTFL-AT (Agile Tester) extension if you work in Agile teams
- CTAL-TA (Test Analyst) at senior level — see the guide