Stware Testing Interview Questions and Answers

Answer: Software testing is an important part of the software development process. In normal software development there are four important steps, also referred to, in short, as the PDCA (Plan, Do, Check, Act) cycle. Let's review the four steps in detail. Plan: Define the goal and the plan for achieving that goal. Do/Execute: Depending on the plan strategy decided during the plan stage we do execution accordingly in this phase. Check: Check/Test to ensure that we are moving according to plan and are getting the desired results. Act: During the check cycle, if any issues are there, then we take appropriate action accordingly and revise our plan again. ...

Answer: Black box testing is a testing strategy based solely on requirements and specifications. Black box testing requires no knowledge of internal paths, structures, or implementation of the software being tested. White box testing is a testing strategy based on internal paths, code structures, and implementation of the software being tested. White box testing generally requires detailed programming skills. There is one more type of testing called gray box testing. In this we look into the "box" being tested just long enough to understand how it has been implemented. Then we close up the box and use our knowledge to choose more effective black box ...

Answer: Usability testing is a testing methodology where the end customer is asked to use the software to see if the product is easy to use, to see the customer's perception and task time. The best way to finalize the customer point of view for usability is by using prototype or mock-up software during the initial stages. By giving the customer the prototype before the development start-up we confirm that we are not missing anything from the user point of view.

Answer: There are three main categories of defects: Wrong: The requirements have been implemented incorrectly. This defect is a variance from the given specification. Missing: There was a requirement given by the customer and it was not done. This is a variance from the specifications, an indication that a specification was not implemented, or a requirement of the customer was not noted properly. Extra: A requirement incorporated into the product that was not given by the end customer. This is always a variance from the specification, but may be an attribute desired by the user of the product. However, it is considered a defect because it's a varianc...

Answer: The following are the important steps used to define a testing policy in general. But it can change according to your organization. Let's discuss in detail the steps of implementing a testing policy in an organization. Definition: The first step any organization needs to do is define one unique definition for testing within the organization so that everyone is of the same mindset. How to achieve: How are we going to achieve our objective? Is there going to be a testing committee, will there be compulsory test plans which need to be executed, etc?. Evaluate: After testing is implemented in a project how do we evaluate it? Are we going to deriv...

Answer: In any project the acceptance document is normally prepared using the following inputs. This can vary from company to company and from project to project. Requirement document: This document specifies what exactly is needed in the project from the customers perspective. Input from customer: This can be discussions, informal talks, emails, etc. Project plan: The project plan prepared by the project manager also serves as good input to finalize your acceptance test. The following diagram shows the most common inputs used to prepare acceptance test plans.

Answer: Configuration management is the detailed recording and updating of information for hardware and software components. When we say components we not only mean source code. It can be tracking of changes for software documents such as requirement, design, test cases, etc. When changes are done in adhoc and in an uncontrolled manner chaotic situations can arise and more defects injected. So whenever changes are done it should be done in a controlled fashion and with proper versioning. At any moment of time we should be able to revert back to the old version. The main intention of configuration management is to track our changes if we have issues w...

Answer: While doing testing on the actual product, the code coverage testing tool is run simultaneously. While the testing is going on, the code coverage tool monitors the executed statements of the source code. When the final testing is completed we get a complete report of the pending statements and also get the coverage percentage.

Answer: In real projects, tailored models are proven to be the best, because they share features from The Waterfall, Iterative, Evolutionary models, etc., and can fit into real life time projects. Tailored models are most productive and beneficial for many organizations. If it's a pure testing project, then the V model is the best.

Answer: When a defect reaches the end customer it is called a failure and if the defect is detected internally and resolved it's called a defect.

Answer: In traditional testing methodology testing is always done after the build and execution phases. But that's a wrong way of thinking because the earlier we catch a defect, the more cost effective it is. For instance, fixing a defect in maintenance is ten times more costly than fixing it during execution. In the requirement phase we can verify if the requirements are met according to the customer needs. During design we can check whether the design document covers all the requirements. In this stage we can also generate rough functional data. We can also review the design document from the architecture and the correctness perspectives. In the bu...

Answer: The design phase is more error prone than the execution phase. One of the most frequent defects which occur during design is that the product does not cover the complete requirements of the customer. Second is wrong or bad architecture and technical decisions make the next phase, execution, more prone to defects. Because the design phase drives the execution phase it's the most critical phase to test. The testing of the design phase can be done by good review. On average, 60% of defects occur during design and 40% during the execution phase.

Answer: When it comes to testing everyone in the world can be involved right from the developer to the project manager to the customer. But below are different types of team groups which can be present in a project. Isolated test team Outsource - we can hire external testing resources and do testing for our project. Inside test team Developers as testers QA/QC team.

Answer: Normally, the impact ratings for defects are classified into three types: Minor: Very low impact but does not affect operations on a large scale. Major: Affects operations on a very large scale. Critical: Brings the system to a halt and stops the show.

Answer: No an increase in testing does not always mean improvement of the product, company, or project. In real test scenarios only 20% of test plans are critical from a business angle. Running those critical test plans will assure that the testing is properly done. The following graph explains the impact of under testing and over testing. If you under test a system the number of defects will increase, but if you over test a system your cost of testing will increase. Even if your defects come down your cost of testing has gone up.

Answer: Environment reality becomes more important as test phases start moving ahead. For instance, during unit testing you need the environment to be partly real, but at the acceptance phase you should have a 100% real environment, or we can say it should be the actual real environment. The following graph shows how with every phase the environment reality should also increase and finally during acceptance it should be 100% real.

Answer: Verification is static type of s/w testing. It means code is not executed. The product is evaluated by going through the code. Types of verification are: Walkthrough: Walkthroughs are informal, initiated by the author of the s/w product to a colleague for assistance in locating defects or suggestions for improvements. They are usually unplanned. Author explains the product; colleague comes out with observations and author notes down relevant points and takes corrective actions. Inspection: Inspection is a thorough word-by-word checking of a software product with the intention of Locating defects, Confirming traceability of relevant requiremen...

Answer: The following figure shows pictorially how test documents span across the software development lifecycle. The following discusses the specific testing documents in the lifecycle: Central/Project test plan: This is the main test plan which outlines the complete test strategy of the software project. This document should be prepared before the start of the project and is used until the end of the software development lifecycle. Acceptance test plan: This test plan is normally prepared with the end customer. This document commences during the requirement phase and is completed at final delivery. System test plan: This test plan starts during the...

Answer: Normally black box test cases are written first and white box test cases later. In order to write black box test cases we need the requirement document and, design or project plan. All these documents are easily available at the initial start of the project. White box test cases cannot be started in the initial phase of the project because they need more architecture clarity which is not available at the start of the project. So normally white box test cases are written after black box test cases are written. Black box test cases do not require system understanding but white box testing needs more structural understanding. And structural unde...

Answer: Unit testing - Testing performed on a single, stand-alone module or unit of code. Integration Tests - Testing performed on groups of modules to ensure that data and control are passed properly between modules. System testing - Testing a predetermined combination of tests that, when executed successfully meets requirements. Acceptance testing - Testing to ensure that the system meets the needs of the organization and the end user or customer (i.e., validates that the right system was built).

Answer: The IEEE Std. 829-1998 defines a test log as a chronological record of relevant details about the execution of test cases. It's a detailed view of activity and events given in chronological manner. The following figure shows a test log and is followed by a sample test log.

Answer: In most organizations testing only starts after the execution/coding phase of the project. But if the organization wants to really benefit from testing, then testers should get involved right from the requirement phase. If the tester gets involved right from the requirement phase then requirement traceability is one of the important reports that can detail what kind of test coverage the test cases have.

Answer: Entry and exit criteria are a must for the success of any project. If you do not know where to start and where to finish then your goals are not clear. By defining exit and entry criteria you define your boundaries. For instance, you can define entry criteria that the customer should provide the requirement document or acceptance plan. If this entry criteria is not met then you will not start the project. On the other end, you can also define exit criteria for your project. For instance, one of the common exit criteria in projects is that the customer has successfully executed the acceptance test plan.

Answer: Verification is a review without actually executing the process while validation is checking the product with actual execution. For instance, code review and syntax check is verification while actually running the product and checking the results is validation.

Answer: A latent defect is an existing defect that has not yet caused a failure because the sets of conditions were never met. A masked defect is an existing defect that hasn't yet caused a failure just because another defect has prevented that part of the code from being executed.

Answer: It includes tracing the accuracy of the devices used in the production, development and testing. Devices used must be maintained and calibrated to ensure that it is working in good order.

Answer: Alpha and beta testing has different meanings to different people. Alpha testing is the acceptance testing done at the development site. Some organizations have a different visualization of alpha testing. They consider alpha testing as testing which is conducted on early, unstable versions of software. On the contrary beta testing is acceptance testing conducted at the customer end. In short, the difference between beta testing and alpha testing is the location where the tests are done.

Answer: A risk is a condition that can result in a loss. Risk can only be controlled in different scenarios but not eliminated completely. A defect normally converts to a risk.

Answer: Coverage is a measurement used in software testing to describe the degree to which the source code is tested. There are three basic types of coverage techniques as shown in the following figure: Statement coverage: This coverage ensures that each line of source code has been executed and tested. Decision coverage: This coverage ensures that every decision (true/false) in the source code has been executed and tested. Path coverage: In this coverage we ensure that every possible route through a given part of code is executed and tested.

Answer: If a defect is known at the initial stage then it should be removed during that stage/phase itself rather than at some later stage. It's a recorded fact that if a defect is delayed for later phases it proves more costly. The following figure shows how a defect is costly as the phases move forward. A defect if identified and removed during the requirement and design phase is the most cost effective, while a defect removed during maintenance is 20 times costlier than during the requirement and design phases. For instance, if a defect is identified during requirement and design we only need to change the documentation, but if identified during t...

Answer: The product has to be used by the user. He is the most important person as he has more interest than anyone else in the project. From the user we need the following data: The first thing we need is the acceptance test plan from the end user. The acceptance test defines the entire test which the product has to pass so that it can go into production. We also need the requirement document from the customer. In normal scenarios the customer never writes a formal document until he is really sure of his requirements. But at some point the customer should sign saying yes this is what he wants. The customer should also define the risky sections of th...

Answer: In order to understand testing methodology we need to understand the workbench concept. A Workbench is a way of documenting how a specific activity has to be performed. A workbench is referred to as phases, steps, and tasks as shown in the following figure. There are five tasks for every workbench: Input: Every task needs some defined input and entrance criteria. So for every workbench we need defined inputs. Input forms the first steps of the workbench. Execute: This is the main task of the workbench which will transform the input into the expected output. Check: Check steps assure that the output after execution meets the desired result. Pr...

Answer: Defect cascading is a defect which is caused by another defect. One defect triggers the other defect. For instance, in the accounting application shown here there is a defect which leads to negative taxation. So the negative taxation defect affects the ledger which in turn affects four other modules.

Answer: When we install the application at the end client it is very possible that on the same PC other applications also exist. It is also very possible that those applications share common DLLs, resources etc., with your application. There is a huge chance in such situations that your changes can affect the cohabiting software. So the best practice is after you install your application or after any changes, tell other application owners to run a test cycle on their application.

Answer: The difference between pilot and beta testing is that pilot testing is nothing but actually using the product (limited to some users) and in beta testing we do not input real data, but it's installed at the end customer to validate if the product can be used in production.

Answer: There are four major ways of rolling out any project: Pilot: The actual production system is installed at a single or limited number of users. Pilot basically means that the product is actually rolled out to limited users for real work. Gradual Implementation: In this implementation we ship the entire product to the limited users or all users at the customer end. Here, the developers get instant feedback from the recipients which allow them to make changes before the product is available. But the downside is that developers and testers maintain more than one version at one time. Phased Implementation: In this implementation the product is rol...

Answer: Acceptance testing checks the system against the "Requirements." It is similar to System testing in that the whole system is checked but the important difference is the change in focus: System testing checks that the system that was specified has been delivered. Acceptance testing checks that the system will deliver what was requested. The customer should always do Acceptance testing and not the developer. The customer knows what is required from the system to achieve value in the business and is the only person qualified to make that judgement. This testing is more about ensuring that the software is delivered as defined by the customer. It'...

Answer: Regression testing is used for regression defects. Regression defects are defects occur when the functionality which was once working normally has stopped working. This is probably because of changes made in the program or the environment. To uncover such kind of defect regression testing is conducted. The following figure shows the difference between regression and confirmation testing. If we fix a defect in an existing application we use confirmation testing to test if the defect is removed. It's very possible because of this defect or changes to the application that other sections of the application are affected. So to ensure that no other...

Answer: A software process is a series of steps used to solve a problem. The following figure shows a pictorial view of how an organization has defined a way to solve risk problems. In the diagram we have shown two branches: one is the process and the second branch shows a sample risk mitigation process for an organization. For instance, the risk mitigation process defines what step any department should follow to mitigate a risk. The process is as follows: Identify the risk of the project by discussion, proper requirement gathering, and forecasting. Once you have identified the risk prioritize which risk has the most impact and should be tackled on ...

Answer: Below are some of the cost elements involved in the implementing process: Salary: This forms the major component of implementing any process, the salary of the employees. Normally while implementing a process in a company either organization can recruit full-time people or they can share resources part-time for implementing the process. Consultant: If the process is new it can also involve consultants which are again an added cost. Training Costs: Employees of the company may also have to undergo training in order to implement the new process Tools: In order to implement the process an organization will also need to buy tools which again need...

Answer: A maturity level specifies the level of performance expected from an organization.

Answer: A model is nothing but best practices followed in an industry to solve issues and problems. Models are not made in a day but are finalized and realized by years of experience and continuous improvements. Many companies reinvent the wheel rather than following time tested models in the industry.

Answer: A process area is the area of improvement defined by CMMI. Every maturity level consists of process areas. A process area is a group of practices or activities performed collectively to achieve a specific objective. For instance, you can see from the following figure we have process areas such as project planning, configuration management, and requirement gathering.

Answer: As the name suggests, tailoring is nothing but changing an action to achieve an objective according to conditions. Whenever tailoring is done there should be adequate reasons for it. Remember when a process is defined in an organization it should be followed properly. So even if tailoring is applied the process is not bypassed or omitted.

Answer: In some projects there are scenarios where we need to do boundary value testing. For instance, let's say for a bank application you can withdraw a maximum of 25000 and a minimum of 100. So in boundary value testing we only test the exact boundaries rather than hitting in the middle. That means we only test above the max and below the max. This covers all scenarios. The following figure shows the boundary value testing for the bank application which we just described. TC1 and TC2 are sufficient to test all conditions for the bank. TC3 and TC4 are just duplicate/redundant test cases which really do not add any value to the testing. So by applyi...

Answer: In equivalence partitioning we identify inputs which are treated by the system in the same way and produce the same results. You can see from the following figure applications TC1 and TC2 give the same results (i.e., TC3 and TC4 both give the same result, Result2). In short, we have two redundant test cases. By applying equivalence partitioning we minimize the redundant test cases. So apply the test below to see if it forms an equivalence class or not: All the test cases should test the same thing. They should produce the same results. If one test case catches a bug, then the other should also catch it. If one of them does not catch the defec...

Answer: Random testing is sometimes called monkey testing. In Random testing, data is generated randomly often using a tool. For instance, the following figure shows how randomly-generated data is sent to the system. This data is generated either using a tool or some automated mechanism. With this randomly generated input the system is then tested and results are observed accordingly. Random testing has the following weakness: They are not realistic. Many of the tests are redundant and unrealistic. You will spend more time analyzing results. You cannot recreate the test if you do not record what data was used for testing. This kind of testing is real...

Answer: As the name specifies semi-random testing is nothing but controlling random testing and removing redundant test cases. So what we do is perform random test cases and equivalence partitioning to those test cases, which in turn removes redundant test cases, thus giving us semi-random test cases.

Answer: Orthogonal array is a two-dimensional array in which if we choose any two columns in the array and all the combinations of numbers will appear in those columns. The following figure shows a simple L9(34) orthogonal array. In this the number 9 indicates that it has 9 rows. The number 4 indicates that it has 4 columns and 3 indicates that each cell contains a 1, 2, and 3. Choose any two columns. Let's choose column 1 and 2. It has (1,1), (1,2), (1,3), (2,1), (2,2), (2,3), (3,1), (3,2), (3,3) combination values. As you can see these values cover all the values in the array. Compare the values with the combination of column 3 and 4 and they will ...

Answer: A negative test is when you put in an invalid input and receive errors. A positive test is when you put in a valid input and expect some action to be completed in accordance with the specification.

Answer: There are four types of severity ratings as shown in the table: Severity 1 (showstoppers): These kinds of defects do not allow the application to move ahead. So they are also called showstopper defects. Severity 2 (application continues with severe defects): Application continues working with these types of defects, but they can have high implications, later, which can be more difficult to remove. Severity 3 (application continues with unexpected results): In this scenario the application continues but with unexpected results. Severity 4 (suggestions): Defects with these severities are suggestions given by the customer to make the application...

Answer: Exploratory testing is also called adhoc testing, but in reality it's not completely adhoc. Ad hoc testing is an unplanned, unstructured, may be even an impulsive journey through the system with the intent of finding bugs. Exploratory testing is simultaneous learning, test design, and test execution. In other words, exploratory testing is any testing done to the extent that the tester proactively controls the design of the tests as those tests are performed and uses information gained while testing to design better tests. Exploratory testers are not merely keying in random data, but rather testing areas that their experience (or imagination) ...

Answer: As the name suggests they are tables that list all possible inputs and all possible outputs. A general form of decision table is shown in the following figure. Condition 1 through Condition N indicates various input conditions. Action 1 through Condition N are actions that should be taken depending on various input combinations. Each rule defines unique combinations of conditions that result in actions associated with that rule.

Answer: There are five methodologies most frequently used: Top down according to budget WBS (Work Breakdown Structure) Guess and gut feeling Early project data TPA (Test Point Analysis)

Answer: TPA is a technique used to estimate test efforts for black box testing. Inputs for TPA are the counts derived from function points. Below are the features of TPA: Used to estimate only black box testing. Require function points as inputs.

Answer: Software applications are a combination of elementary processes. When elementary processes come together they form a software application. There are two types of elementary processes: Dynamic elementary Process: The dynamic elementary process moves data from an internal application boundary to an external application boundary or vice-versa. Example: Input data screen where a user inputs data into the application. Data moves from the input screen inside the application. Static elementary Process: Static elementary process which maintains the data of the application either inside the application boundary or in the external application boundary....

Answer: The testing estimates derived from function points are actually the estimates for white box testing. So in the following figure the man days are actually the estimates for white box testing of the project. It does not take into account black box testing estimation.

Answer: File Type References (FTRs): An FTR is a file or data referenced by a transaction. An FTR should be an ILF or EIF. So count each ILF or EIF read during the process. If the EP is maintained as an ILF then count that as an FTR. So by default you will always have one FTR in any EP. Internal Logical Files (ILFs): ILFs are logically related data from a user's point of view. They reside in the internal application boundary and are maintained through the elementary process of the application.ILFs can have a maintenance screen but not always. External Interface Files (EIFs): EIFs reside in the external application boundary. EIFs are used only for ref...

Answer: The first step in FPA is to define the boundary. There are two types of major boundaries: Internal Application Boundary External Application Boundary The external application boundary can be identified using the following litmus test: Does it have or will it have any other interface to maintain its data, which was not developed by you?. Does your program have to go through a third party API or layer? In order for your application to interact with the tax department application your code has to interact with the tax department API. The best litmus test is to ask yourself if you have full access to the system. If you have full rights to make ch...

Answer: There are three main elements which determine estimates for black box testing: size, test strategy, and productivity. Using all three elements we can determine the estimate for black box testing for a given project. Let's take a look at these elements. Size: The most important aspect of estimating is definitely the size of the project. The size of a project is mainly defined by the number of function points. But a function point fails or pays the least attention to the following factors: Complexity: Complexity defines how many conditions exist in function points identified during a project. More conditions means more test cases which means mo...

Answer: Below are the steps in function points: First Count ILF, EIF, EI, EQ, RET, DET, FTR and use the rating tables. After you have counted all the elements you will get the unadjusted function points. Put rating values 0 to 5 to all 14 GSC. Adding total of all 14 GSC to come out with total VAF. Formula for VAF = 0.65 + (sum of all GSC factor/100). Finally, make the calculation of adjusted function point. Formula: Total function point = VAF * Unadjusted function point. Make estimation how many function points you will do per day. This is also called as "Performance factor".On basis of performance factor, you can calculate Man/Days.

Answer: Function points are a unit measure for software much like an hour is to measuring time, miles are to measuring distance or Celsius is to measuring temperature. Function Points are an ordinal measure much like other measures such as kilometers, Fahrenheit, hours, so on and so forth. This approach computes the total function points (FP) value for the project, by totaling the number of external user inputs, inquiries, outputs, and master files, and then applying the following weights: inputs (4), outputs (5), inquiries (4), and master files (10). Each FP contributor can be adjusted within a range of +/-35% for a specific project complexity.