Curated interview practice questions with answers. These are practice scenarios, not a verified list of past interview questions.
About TCS hiring for ISTQB roles
Tata Consultancy Services is a Tata Group company and one of the largest IT services and consulting firms in the world. It delivers application development, testing, cloud, data and analytics services to clients in banking, retail, manufacturing and other industries. In India it hires freshers and experienced staff for software testing, data engineering, BI reporting and analytics roles across its delivery centres.
For ISTQB roles, this TCS practice set focuses most on Managing the Test Activities (7), White-Box, Experience and Collaboration-Based Testing (7), Fundamentals of Testing (6), Defect and Configuration Management (2). It has 16 easy, 13 medium, 1 hard questions, so you can start easy and work up to the harder ones.
Company type
IT services
Headquarters
Mumbai, India
Main India offices
Mumbai, Chennai, Pune, Bengaluru, Hyderabad
TCS ISTQB interview process
TCS NQT online assessment (aptitude + coding)
Technical interview
Managerial round
HR round
Typical pattern based on public candidate experiences. Rounds vary by role, team and year.
Solved for TCSStart practicing
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01
Write a sample defect report for a failed coupon code.
Almost any work product that can be read and understood: requirements, user stories, acceptance criteria, architecture and design documents, source code, test plans, test cases, test charters, backlog items, contracts, project plans, schedules and budgets. Static analysis tools need work products with a formal structure, such as code or models with defined syntax. Products that are hard for humans to interpret, like third-party executable code, are not suitable for review.
03
Which good testing practices apply regardless of the SDLC model?
CTFL v4.0 lists these: for every software development activity there is a corresponding test activity; each test level has its own specific objectives; test analysis and design for a level begin during the corresponding development phase; and testers are involved in reviewing work products as soon as drafts are available. Together these practices support early testing and quality control in waterfall, V-model and Agile projects alike.
04
Order these tests for execution: A (priority 1, depends on C), B (priority 2), C (priority 3), D (priority 2, depends on B). 1 is highest.
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.
05
Marks from 0 to 100 give: 0-39 fail, 40-59 pass, 60-100 distinction. How many partitions and 2-value boundary values are there?
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.
06
Match these tasks to test activities: identifying test conditions, creating test data and suites, comparing actual and expected results, archiving testware.
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.
07
Explain error, defect, failure and root cause with an example.
A human makes an error (mistake), for example misreading a requirement. The error produces a defect (fault or bug) in a work product such as code or a document. When defective code is executed it may cause a failure, meaning the system does something wrong or fails to do something. The root cause is the fundamental reason for the error, such as time pressure or unclear requirements. Failures can also come from environmental conditions like radiation.
08
Historically, development and test effort are in the ratio 3:2. Development is estimated at 600 person-days. Estimate the test effort.
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.
White-box testing considers the whole implementation, so it can find defects even when the specification is vague, outdated or incomplete. Coverage gives an objective measure of thoroughness. It can also be used in static testing, for example dry runs of code or pseudocode. Its main weakness is that it cannot detect omissions: if a requirement was never implemented, no white-box test will notice it.
10
What is the difference between testing and debugging?
Testing triggers failures caused by defects (dynamic testing) or finds defects directly in work products (static testing). Debugging is a development activity that reproduces a failure, diagnoses the root cause and fixes the defect. After the fix, testers run confirmation testing to check the fix and regression testing to check nothing else broke. In short, testing finds and reports problems, while debugging locates and removes them.
11
Discount depends on customer type (regular, gold, platinum) and whether the order exceeds 1,000 rupees. How many rules does the full decision table have?
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.
12
Are there prerequisites for CTFL, and does the certificate expire?
There are no formal prerequisites for the Foundation Level exam; students, freshers and experienced professionals can all take it, although some practical testing exposure makes the syllabus easier. The CTFL certificate has lifetime validity and does not need renewal. It is the prerequisite for ISTQB Advanced Level and most Specialist certifications, so it is the starting point of the ISTQB path.
13
A tester uses past experience to test division by zero, empty fields and invalid dates. Which technique is this?
This is error guessing, an experience-based technique. The tester anticipates mistakes based on knowledge of similar applications, typical developer errors and past failures. When done methodically by listing possible errors and designing tests for each, it is called a fault attack. It is not checklist-based testing unless the tester works from a prepared checklist of conditions.
The two common formats are scenario-oriented, such as the Given/When/Then style used in BDD, and rule-oriented, such as a bullet-point verification list or a tabulated input-output mapping. Acceptance criteria define the scope of the story, reach consensus among stakeholders, describe positive and negative scenarios, serve as the basis for acceptance testing and support accurate planning and estimation. Teams can also use other formats as long as criteria are well defined and clear.
15
Why do you want to start your career in software testing?
Model answer: I enjoy finding how things break and thinking from the user's side. During my degree I tested our team project and found issues others missed, which built my interest. I studied the ISTQB Foundation syllabus to learn standard terms and techniques. I want to grow from manual testing into automation and domain expertise, and testing lets me understand the whole product and the full SDLC.
16
What are entry and exit criteria? How do they relate to Definition of Ready and Definition of Done?
Entry criteria define preconditions for starting an activity, such as available resources, testware, a stable build and a test environment. Exit criteria define what must be achieved to finish, such as coverage reached, unresolved defect counts, defect density and passed tests. Running out of time or budget can also be a valid exit. In Agile, exit criteria are often called the Definition of Done and entry criteria for a story the Definition of Ready.
17
What is statement testing and how is statement coverage calculated?
Statement testing designs tests that execute the executable statements in the code. Statement coverage = statements executed by the tests / total executable statements x 100. Reaching 100 percent means every executable statement ran at least once, so a defect in any statement may be triggered. However, it does not guarantee that all decision logic is tested, for example the false outcome of an if without an else.
18
Tell me about a time you found an important defect. How did you report it?
Situation: while testing our final-year e-commerce project, I found checkout accepted expired coupon codes. Task: report it clearly before the demo. Action: I reproduced it three times and logged clear steps, expected and actual results, screenshots and the coupon data, and marked severity high because it meant revenue loss. Result: the developer fixed it within a day, and I added a regression test for coupon expiry.
19
What is the difference between a test progress report and a test completion report?
A test progress report is produced regularly during testing, for example daily or per sprint. It covers the period, progress against plan, impediments, metrics, new or changed risks and planned work. A test completion report is prepared at the end of a test level, iteration or project. It summarises testing, evaluates quality against the plan, lists deviations, unmitigated risks, open defects, metrics and lessons learned.
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.
21
Write a test charter for an exploratory session on a checkout page.
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.
22
What does a test plan contain according to CTFL v4.0?
A test plan typically covers: context of testing (scope, objectives, constraints, test basis); assumptions and constraints; stakeholders with roles and responsibilities; communication; a risk register of product and project risks; the test approach (test levels, types, techniques, deliverables, entry and exit criteria, independence, metrics, test data and environments); and budget and schedule. It documents how test objectives will be met and is updated as the project changes.
A defect is logged as new or open, then triaged: it may be rejected, marked duplicate or deferred, or assigned for fixing. After the developer fixes it, it moves to awaiting confirmation testing. The tester re-tests; if it passes, the defect is closed, and if it fails, it is re-opened. Teams customise the workflow, but each status should have clear rules about who can move it and when.
24
How many tests are needed for full statement and branch coverage of this nested code?
if a > 0:
if b > 0:
s1
else:
s2
else:
s3
Statement coverage needs 3 tests, because s1, s2 and s3 are on different paths.
Branch coverage also needs 3: (a > 0, b > 0), (a > 0, b <= 0) and (a <= 0).
With full if-else structures, both criteria need the same number of tests.
25
Why does 100 percent branch coverage guarantee 100 percent statement coverage, but not the other way round?
Every statement lies on at least one branch, so exercising all branches executes all statements. The reverse fails when a decision has an empty outcome. Example: 'if x > 10: print(big)' followed by 'print(done)'. One test with x = 15 runs every statement, giving 100 percent statement coverage, but the false branch is never taken, so branch coverage is only 50 percent. This is called subsumption.
26
What happens in test monitoring, test control and test completion?
Test monitoring gathers information about testing to check progress and whether exit criteria are met, using metrics like test case progress, defect counts, coverage and cost. Test control uses that information to give guidance and corrective actions, such as reprioritising tests or changing the schedule. Test completion collects data from finished activities to consolidate experience, testware and other information, usually at milestones like release or end of iteration.
Static testing detects defects in the earliest phases, when they are cheapest to fix. It finds defects that dynamic testing cannot, such as unreachable code or defects in non-executable work products. It helps evaluate quality and build confidence, improves shared understanding among stakeholders, and gives fast feedback on code through static analysis in CI. Reviews cost effort, but the total cost of quality is usually lower.
The test pyramid shows that tests have different granularity and that a healthy suite has many small, fast, isolated tests at the bottom, such as unit or component tests, and fewer large, slow, complex end-to-end tests at the top, such as UI tests. Middle layers often cover API or integration tests. The pyramid helps teams plan automation so the suite is fast, stable and cheap to maintain.
29
How does testing relate to quality assurance and quality control?
Testing is a form of quality control (QC): a product-oriented, corrective approach that checks work products. Quality assurance (QA) is process-oriented and preventive: it improves processes on the idea that a good process produces a good product. Test results are used by both. QC uses them to fix defects, and QA uses them as feedback on how well the development and test processes are performing.
30
What is the difference between verification and validation?
Verification checks whether the system meets its specified requirements: 'Are we building the product right?' Validation checks whether the system meets user and stakeholder needs in its operational environment: 'Are we building the right product?' Both are testing objectives. Example: verification confirms the eight-character password rule is implemented, while validation checks that real users can actually register easily on a mobile phone.
Tips to crack the TCS ISTQB interview
Practise TCS NQT style numerical, verbal and reasoning sections along with two basic coding problems under strict time limits.
Be ready to explain your final-year project, SQL basics and core concepts like OOP, DBMS and software testing life cycle.
Read about TCS service lines such as BFSI and its iON and Ignio platforms to answer why you want to join.
Keep a one-minute story ready for every project on your CV: problem, your part, tools, result.
Practise the hard questions on this page aloud; TCS interviewers usually ask follow-ups on your first answer.
Frequently asked questions
How many rounds are there in the TCS ISTQB interview?
Candidates usually go through 4 stages: TCS NQT online assessment (aptitude + coding); Technical interview; Managerial round; HR round. The exact rounds change with the role, team, location and your experience, so confirm the process with the recruiter.
Which topics should I prepare for the TCS ISTQB interview?
This practice set leans on Managing the Test Activities (7), White-Box, Experience and Collaboration-Based Testing (7), Fundamentals of Testing (6), Defect and Configuration Management (2). Revise those first, then practise explaining one or two of your own projects end to end, because most TCS interviewers ask you to walk through real work.
Are these the exact questions asked at TCS?
No. These are curated practice questions that match the skills and difficulty usually tested in it services interviews like TCS's. They are not a leaked or verified list of past questions.
Where does TCS hire ISTQB professionals in India?
TCS has large teams in Mumbai, Chennai, Pune, Bengaluru, Hyderabad. Openings and locations change often, so check the TCS careers page and filter by city and experience.