Practical ISTQB Interview Questions

Identifying and prioritising test conditions is test analysis. Creating test data, arranging test procedures and assembling test suites is test implementation. Running tests and comparing actual with expected results is test execution. Archiving testware, handing it over and recording lessons learned is test completion. Exams often mix design and implementation: designing test cases is test design, while preparing them to run is implementation.

Read the test basis and list testable aspects. Conditions: a transfer within the limit succeeds; a transfer of exactly 50,000 succeeds; a transfer above 50,000 is rejected with a clear message; several transfers in one day are added together against the limit; the limit resets the next day; zero or negative amounts are rejected. Prioritise them by risk, then design test cases with exact amounts using boundary value analysis.

Collect the failure details and logs, reproduce the issue and identify the defect. Then ask 'why' repeatedly until you reach a process cause. Example: a wrong discount was shown; why? the code used an old rule; why? the requirement changed without notice; why? there was no change review step. Action: add change notifications and a review step. Fixing root causes prevents whole families of similar defects.

Identify changed items from commits and change requests; use traceability to find affected requirements, components and interfaces; check dependency maps and defect history; rank the affected areas by risk; select automated regression for broad coverage plus targeted manual tests for high-risk flows; and document what is excluded and why. Impact analysis can also help decide whether a risky change should be made at all.

Is it written as 'As a [role], I want [goal], so that [benefit]'? Does it follow INVEST: independent, negotiable, valuable, estimable, small and testable? Are acceptance criteria clear, measurable and testable? Are error flows and edge cases covered? Are terms consistent with the glossary? Are dependencies and non-functional needs stated? Are vague words like 'quickly' or 'etc.' present? Log each anomaly with location, description and a suggestion.

Plan: define scope, objective and exit criteria and choose reviewers with the right expertise. Initiate: share the document, checklist and timeline. Individual review: each reviewer logs anomalies in a shared tool. Communication and analysis: the moderator runs the meeting, the team discusses anomalies and agrees actions. Fixing and reporting: the author updates the document, defects are tracked, and results are checked against exit criteria.

Check that inputs are validated and errors handled; comparisons at boundaries are correct, such as less than versus less than or equal; variables are initialised before use; there are no hard-coded passwords or secrets; logs avoid personal data; duplicated code is removed; complexity is reasonable; and unit tests cover new logic and edge cases. Combine manual review with static analysis tools for routine checks.

There are three partitions: below 18 (invalid), 18 to 60 (valid) and above 60 (invalid). Pick one value from each, for example 10, 35 and 70. So three test cases give 100 percent EP coverage. Test invalid partitions one at a time so that one invalid value does not hide another, and confirm with the specification whether non-numeric input forms another invalid partition.

The valid partition is 1 to 100, with invalid partitions below and above it. For each boundary, take the boundary and its closest neighbour in the adjacent partition. Lower boundary: 0 and 1. Upper boundary: 100 and 101. So 2-value BVA needs four values: 0, 1, 100 and 101, and four test cases give 100 percent 2-value boundary coverage.

In 3-value BVA, each boundary gives the boundary value plus both neighbours. Lower boundary 5 gives 4, 5 and 6. Upper boundary 15 gives 14, 15 and 16. So the six values are 4, 5, 6, 14, 15 and 16. Compared with 2-value BVA (4, 5, 15, 16), the extra values 6 and 14 help detect mistakes in comparison operators inside the range.

Each Choice coverage needs every partition from each input used at least once, and one test can cover one partition of each input at the same time. So the minimum equals the largest number of partitions: 3. Example tests: card with new, UPI with existing, wallet with new. Covering all combinations would need 3 x 2 = 6 tests, which is not required for Each Choice.

A full table has 2 to the power 3 = 8 columns. When A is false, the other two conditions do not matter, so those four columns merge into one column with dashes for B and C. When A is true, the four combinations of B and C remain. The minimised table has 4 + 1 = 5 columns, so 5 tests give full coverage, if all columns are feasible.

A state table lists states as rows and events as columns, and each cell shows the resulting state or marks the transition as invalid. Example: a document workflow with states Draft, Review and Published, and events submit, approve and reject. Draft with approve is invalid. Valid cells are coverage items for valid transitions coverage; invalid cells are tested for all transitions coverage, one per test case.

The partitions by length are 0 to 7 (invalid), 8 to 16 (valid) and 17 or more (invalid). 2-value BVA takes each boundary and its closest neighbour: 7 and 8 for the lower boundary, 16 and 17 for the upper boundary. So test passwords of length 7, 8, 16 and 17 characters, keeping other rules such as character types valid so only the length varies.

EP coverage = exercised partitions / identified partitions x 100 = 4 / 6 x 100 = 66.7 percent. Adding another test in an already covered partition does not increase coverage, because coverage counts partitions, not tests. To reach 100 percent you need tests in the two missing partitions. Exams often include such distractors to see if you count tests instead of coverage items.

The closest neighbour depends on the precision, here 0.01. Lower boundary: 0.00 (invalid) and 0.01 (valid). Upper boundary: 999.99 (valid) and 1000.00 (invalid). So the four test values are 0.00, 0.01, 999.99 and 1000.00. Always confirm the precision from the specification, because with whole numbers the neighbour would be 1, and with three decimals it would be 0.001.

Valid partitions: 0-39, 40-59 and 60-100, plus two invalid partitions: below 0 and above 100, so 5 partitions. Boundaries in 2-value BVA: -1, 0, 39, 40, 59, 60, 100 and 101, which is 8 values. Five tests give 100 percent EP coverage, and eight tests give 100 percent 2-value boundary coverage. Note that output partitions like fail, pass and distinction also guide the partitioning.

Partitions: 0 or less is invalid, 1 to 498 pays 40, and 499 or more ships free. EP tests: 0 rejected, 250 pays 40, 800 free. 2-value BVA adds 0 and 1 at the lower edge and 498 and 499 at the free shipping boundary. Combined minimal set: 0, 1, 250, 498, 499 and 800, each with the expected fee clearly stated.

When conditions are not Boolean, multiply the number of values of each condition. Customer type has 3 values and the order condition has 2, so the full table has 3 x 2 = 6 rules. Each rule becomes one test case for 100 percent decision table coverage. If, for example, platinum always gets the same discount regardless of amount, those two columns can be merged, giving 5.

Statement coverage = 8 / 10 x 100 = 80 percent. Branch coverage = 3 / 4 x 100 = 75 percent. To raise them, look at the control flow graph to see which statements and which branch outcome were missed, then design inputs that force execution down those paths. Coverage tools in CI pipelines report these numbers automatically for each build.

Charter: Explore the checkout page with different coupon and payment combinations to discover pricing and rounding errors. Time box: 60 minutes. Focus areas: coupon stacking, expired coupons, quantity changes after applying a coupon, currency rounding, and using the browser back button. Record test ideas, defects, questions and areas covered. Debrief with the test lead after the session to agree next charters.

List likely failures and design tests for each: empty file; file just above the size limit; very large file; wrong extension; correct extension with wrong content; file names with spaces, Unicode or very long names; duplicate names; upload interrupted by network loss; many uploads at once; malicious files such as scripts; and uploads without login or with an expired session. Prioritise by risk.

This is estimation based on ratios. Test effort = development effort x 2 / 3 = 600 x 2 / 3 = 400 person-days. The ratio must come from similar past projects in the same organisation, because it changes with domain, risk and process maturity. I would also cross-check with another technique, such as Wideband Delphi, before committing to the number.

A has the highest priority but depends on C, so C must run first, followed by A. Next come the priority 2 tests: B, then D, because D depends on B. The execution order is C, A, B, D. ISTQB exams often include such questions; always satisfy dependencies first, then follow priority, and run the highest priority test as early as its dependencies allow.

Score each risk for likelihood and impact on a scale such as 1 to 5, and multiply to get the risk level. Example: wrong interest calculation, likelihood 3 and impact 5, level 15; slow report export, likelihood 4 and impact 2, level 8; spelling errors, 4 and 1, level 4. Test the highest levels first and most deeply, using more rigorous techniques and earlier test execution.

Include: summary of testing done and the scope; evaluation of product quality against the test plan and exit criteria; deviations from plan in schedule, effort or scope; impediments faced; metrics such as tests run, passed, failed, coverage and defects by severity; open defects with workarounds; unmitigated residual risks; testware handed over or archived; and lessons learned with improvement actions for the next release.

ID: DEF-1042. Title: Checkout - valid coupon SAVE10 rejected as expired. Build: 3.4.1, staging, Chrome 130 on Windows. Preconditions: logged-in user, cart value 1,500 rupees. Steps: open checkout, enter SAVE10, click Apply. Expected: 10 percent discount applied. Actual: error 'Coupon expired' although valid until 31 December. Attachments: screenshot, console log. Severity: major. Priority: high. Reference: TC-CHK-018.

Defect density = defects / size = 45 / 15 KLOC = 3 defects per KLOC. If other modules average 1 defect per KLOC, this module is a defect cluster, so I would increase test depth there, ask for a code review or refactoring, and add more regression tests. Compare density only across similar code, because language and complexity affect the numbers.

Invite the test lead, a development lead and the product owner. Prepare a filtered list of new and re-opened defects before the meeting. For each defect, confirm it is valid and not a duplicate, agree severity and priority, assign an owner and a target release, or reject or defer it with a reason. Keep it time-boxed, record decisions in the tool, and review ageing critical defects regularly.

Week 1: chapters 1 and 2, the seven principles, test activities, test levels and test types; make notes of key terms. Week 2: chapter 3 and black-box techniques, solving at least 30 EP, BVA, decision table and state transition problems. Week 3: white-box and experience-based techniques, chapters 5 and 6, with estimation and risk exercises. Week 4: three or more timed sample exams and revision of mistakes.

Register through the ISTQB member board for India or an ISTQB-accredited exam provider. Create an account, choose CTFL v4.0, and pick either an online proctored exam or a test centre. For online exams, check your webcam, microphone and internet in advance, and keep a valid government photo ID ready. Results are usually shared soon after the exam, followed by the certificate.

Read the instruction carefully, because you must select exactly two options and usually get the point only if both are correct. Evaluate each option separately as true or false against the syllabus. Eliminate absolute statements and options that describe a different concept. If you are sure of one, compare the remaining options carefully. These questions appear in the exam, so practise them in sample papers.

Each learning objective lists keywords that you must know. Make flashcards for them with the exact glossary definition and one example from your own work, such as 'test basis: the user story for checkout'. Review them daily with spaced repetition. Pay attention to similar terms, like test condition versus test case, and confirmation versus regression testing, because exams use them as distractors.

After each timed attempt, review every question, including correct guesses. For each mistake, note the learning objective, the chapter and why the right option is correct in the syllabus text. Group mistakes by chapter to find weak areas, re-read those sections, and redo similar questions after a few days. Aim for consistent scores of 32 or more out of 40 before the real exam.