Most asked job interview questions and how to answer them

1. Software Testing is more Oriented to Detecting the defects or often equated to finding bugs. Testing is a process of executing a software system to determine whether it matches its specification and executes in its intended environment under controlled conditiions. The controlled conditions should include both normal and abnormal conditions. Testing should intentionally attempt to make things go wrong to determine if things happen when they shouldn't or things don't happen when they should. SQA: - Software QA involves the entire software development PROCESS - monitoring and improving the process, making sure that any agreed-upon standards and procedures are followed, and ensuring that problems are found and dealt with. It is oriented to 'prevention'. Stop Testing: - Testing is potentially endless. We can not test till all the defects are unearthed and removed -- it is simply impossible. At some point, we have to stop testing and ship the software. The question is when.

For Verification & Validation (V&V)

Just as topic Verification and Validation indicated, another important purpose of testing is verification and validation (V&V). Testing can serve as metrics. It is heavily used as a tool in the V&V process. Testers can make claims based on interpretations of the testing results, which either the product works under certain situations, or it does not work. We can also compare the quality among different products under the same specification, based on results from the same test.

2. What is the purpose of software testing?

The purpose of software testing is

a. To demonstrate that the product performs each function intended;

b. To demonstrate that the internal operation of the product performs according to specification and all internal components have been adequately exercised;

c. To increase our confidence in the proper functioning of the software.

d. To show the product is free from defect.

e. All of the above.

3. Types of Levels: -

COMPATIBILITY TESTING. Testing to ensure compatibility of an application or Web site with different browsers, OSs, and hardware platforms. Compatibility testing can be performed manually or can be driven by an automated functional or regression test suite.

CONFORMANCE TESTING. Verifying implementation conformance to industry standards. Producing tests for the behavior of an implementation to be sure it provides the portability, interoperability, and/or compatibility a standard defines.

FUNCTIONAL TESTING. Validating an application or Web site conforms to its specifications and correctly performs all its required functions. This entails a series of tests which perform a feature by feature validation of behavior, using a wide range of normal and erroneous input data. This can involve testing of the product's user interface, APIs, database management, security, installation, networking, etcF testing can be performed on an automated or manual basis using black box or white box methodologies.

LOAD TESTING. Load testing is a generic term covering Performance Testing and Stress Testing.

PERFORMANCE TESTING. Performance testing can be applied to understand your application or WWW site's scalability, or to benchmark the performance in an environment of third party products such as servers and middleware for potential purchase. This sort of testing is particularly useful to identify performance bottlenecks in high use applications. Performance testing generally involves an automated test suite as this allows easy simulation of a variety of normal, peak, and exceptional load conditions.

REGRESSION TESTING. Similar in scope to a functional test, a regression test allows a consistent, repeatable validation of each new release of a product or Web site. Such testing ensures reported product defects have been corrected for each new release and that no new quality problems were introduced in the maintenance process. Though regression testing can be performed manually an automated test suite is often used to reduce the time and resources needed to perform the required testing.

SMOKE TESTING. A quick-and-dirty test that the major functions of a piece of software work without bothering with finer details. Originated in the hardware testing practice of turning on a new piece of hardware for the first time and considering it a success if it does not catch on fire.

STRESS TESTING. Testing conducted to evaluate a system or component at or beyond the limits of its specified requirements to determine the load under which it fails and how. A graceful degradation under load leading to non-catastrophic failure is the desired result. Often Stress Testing is performed using the same process as Performance Testing but employing a very high level of simulated load.

UNIT TESTING. Functional and reliability testing in an Engineering environment. Producing tests for the behavior of components of a product to ensure their correct behavior prior to system integration.

Black Box Testing

Black box testing methods focus on the functional requirements of the software. Tests sets are derived that fully exercise all functional requirements. This strategy tends to be applied during the latter part of the lifecycle.

Tests are designed to answer questions such as:

1) How is functional validity tested?

2) What classes of input make good test cases?

3) Is the system particularly sensitive to certain input values?

4) How are the boundaries of data classes isolated?

5) What data rates or volumes can the system tolerate?

6) What effect will specific combinations of data have on system operation?

Equivalence Partitioning: -

This method divides the input of a program into classes of data. Test case design is based on defining an equivalent class for a particular input. An equivalence class represents a set of valid and invalid input values.

Guidelines for equivalence partitioning -

1) If an input condition specifies a range, one valid and two invalid equivalence classes are defined.

2) If an input condition requires a specific value, one valid and two invalid equivalence classes are defined.

3) If an input condition specifies a member of a set, one valid and one invalid equivalence class are defined.

4) If an input condition is boolean, one valid and one invalid class are defined.

Boundary Value Analysis: -

Boundary value analysis is complementary to equivalence partitioning. Rather than selecting arbitrary input values to partition the equivalence class, the test case designer chooses values at the extremes of the class. Furthermore, boundary value analysis also encourages test case designers to look at output conditions and design test cases for the extreme conditions in output.

Guidelines for boundary value analysis -

1) If an input condition specifies a range bounded by values a and b, test cases should be designed with values a and b, and values just above and just below and b.

2) If an input condition specifies a number of values, test cases should be developed that exercise the minimum and maximum numbers. Values above and below the minimum and maximum are also tested.

3) Apply the above guidelines to output conditions. For example, if the requirement specifies the production of an table as output then you want to choose input conditions that produce the largest and smallest possible table.

4) For internal data structures be certain to design test cases to exercise the data structure at its boundary. For example, if the software includes the maintenance of a personnel list, then you should ensure the software is tested with conditions where the list size is 0, 1 and maximum (if constrained).

Cause-Effect Graphs

A weakness of the two methods is that do not consider potential combinations of input/output conditions. Cause-effect graphs connect input classes (causes) to output classes (effects) yielding a directed graph.

Guidelines for cause-effect graphs -

1) Causes and effects are listed for a modules and an identifier is assigned to each.

2) A cause-effect graph is developed (special symbols are required).

3) The graph is converted to a decision table.

4) Decision table rules are converted to test cases.

We can not test quality directly, but we can test related factors to make quality visible. Quality has three sets of factors -- functionality, engineering, and adaptability. These three sets of factors can be thought of as dimensions in the software quality space. Each dimension may be broken down into its component factors and considerations at successively lower levels of detail.

Performance testing

Not all software systems have specifications on performance explicitly. But every system will have implicit performance requirements. The software should not take infinite time or infinite resource to execute. "Performance bugs" sometimes are used to refer to those design problems in software that cause the system performance to degrade.

Reliability testing

Software reliability refers to the probability of failure-free operation of a system. It is related to many aspects of software, including the testing process. Directly estimating software reliability by quantifying its related factors can be difficult. Testing is an effective sampling method to measure software reliability. Guided by the operational profile, software testing (usually black-box testing) can be used to obtain failure data, and an estimation model can be further used to analyze the data to estimate the present reliability and predict future reliability. Therefore, based on the estimation, the developers can decide whether to release the software, and the users can decide whether to adopt and use the software. Risk of using software can also be assessed based on reliability information. [Hamlet94] advocates that the primary goal of testing should be to measure the dependability of tested software.

Security testing

Software quality, reliability and security are tightly coupled. Flaws in software can be exploited by intruders to open security holes. With the development of the Internet, software security problems are becoming even more severe.

Many critical software applications and services have integrated security measures against malicious attacks. The purpose of security testing of these systems include identifying and removing software flaws that may potentially lead to security violations, and validating the effectiveness of security measures. Simulated security attacks can be performed to find vulnerabilities.

TESTING means "quality control"

* QUALITY CONTROL measures the quality of a product

* QUALITY ASSURANCE measures the quality of processes used to create a quality product.

Beta testing is typically conducted by end users of a software product who are not paid a salary for their efforts.

Acceptance Testing

Testing the system with the intent of confirming readiness of the product and customer acceptance.

Ad Hoc Testing

Testing without a formal test plan or outside of a test plan. With some projects this type of testing is carried out as an adjunct to formal testing. If carried out by a skilled tester, it can often find problems that are not caught in regular testing. Sometimes, if testing occurs very late in the development cycle, this will be the only kind of testing that can be performed. Sometimes ad hoc testing is referred to as exploratory testing.

Alpha Testing

Testing after code is mostly complete or contains most of the functionality and prior to users being involved. Sometimes a select group of users are involved. More often this testing will be performed in-house or by an outside testing firm in close cooperation with the software engineering department.

Automated Testing

Software testing that utilizes a variety of tools to automate the testing process and when the importance of having a person manually testing is diminished. Automated testing still requires a skilled quality assurance professional with knowledge of the automation tool and the software being tested to set up the tests.

Beta Testing

Testing after the product is code complete. Betas are often widely distributed or even distributed to the public at large in hopes that they will buy the final product when it is released.

Black Box Testing

Testing software without any knowledge of the inner workings, structure or language of the module being tested. Black box tests, as most other kinds of tests, must be written from a definitive source document, such as a specification or requirements document..

Compatibility Testing

Testing used to determine whether other system software components such as browsers, utilities, and competing software will conflict with the software being tested.

Configuration Testing

Testing to determine how well the product works with a broad range of hardware/peripheral equipment configurations as well as on different operating systems and software.

Functional Testing

Testing two or more modules together with the intent of finding defects, demonstrating that defects are not present, verifying that the module performs its intended functions as stated in the specification and establishing confidence that a program does what it is supposed to do.

Independent Verification and Validation (IV&V)

The process of exercising software with the intent of ensuring that the software system meets its requirements and user expectations and doesn't fail in an unacceptable manner. The individual or group doing this work is not part of the group or organization that developed the software. A term often applied to government work or where the government regulates the products, as in medical devices.

Installation Testing

Testing with the intent of determining if the product will install on a variety of platforms and how easily it installs.

Integration Testing

Testing two or more modules or functions together with the intent of finding interface defects between the modules or functions. Testing completed at as a part of unit or functional testing, and sometimes, becomes its own standalone test phase. On a larger level, integration testing can involve a putting together of groups of modules and functions with the goal of completing and verifying that the system meets the system requirements. (see system testing)

Load Testing

Testing with the intent of determining how well the product handles competition for system resources. The competition may come in the form of network traffic, CPU utilization or memory allocation.

Performance Testing

Testing with the intent of determining how quickly a product handles a variety of events. Automated test tools geared specifically to test and fine-tune performance are used most often for this type of testing.

Pilot Testing

Testing that involves the users just before actual release to ensure that users become familiar with the release contents and ultimately accept it. Often is considered a Move-to-Production activity for ERP releases or a beta test for commercial products. Typically involves many users, is conducted over a short period of time and is tightly controlled. (see beta testing)

Regression Testing

Testing with the intent of determining if bug fixes have been successful and have not created any new problems. Also, this type of testing is done to ensure that no degradation of baseline functionality has occurred.

Security Testing

Testing of database and network software in order to keep company data and resources secure from mistaken/accidental users, hackers, and other malevolent attackers.

Software Testing

The process of exercising software with the intent of ensuring that the software system meets its requirements and user expectations and doesn't fail in an unacceptable manner. The organization and management of individuals or groups doing this work is not relevant. This term is often applied to commercial products such as internet applications. (contrast with independent verification and validation)

Stress Testing

Testing with the intent of determining how well a product performs when a load is placed on the system resources that nears and then exceeds capacity.

System Integration Testing

Testing a specific hardware/software installation. This is typically performed on a COTS (commercial off the shelf) system or any other system comprised of disparent parts where custom configurations and/or unique installations are the norm.

White Box Testing

Testing in which the software tester has knowledge of the inner workings, structure and language of the software, or at least its purpose.

Difference Between Verification & Validation: -

- Verification is about answering the question "Does the system function properly?" or "Have we built the system right?"

- Validation is about answering the question "Is the product what the customer wanted?" or "Have we built the right system?"

This definition indicates that Validation could be the same thing as Acceptance Test (or at least very similar).

I have often described Verification and Validation processes in the same way, ie:

1. Plan the test (output Test Plan)

2. Specify the test (output Test Specification)

3. Perform the test (output Test Log and/or Test Report

Verification & Validation

Verification typically involves reviews and meetings to evaluate documents, plans, code, requirements, and specifications. This can be done with checklists, issues lists, walkthroughs, and inspection meetings. Validation typically involves actual testing and takes place after verifications are completed. The term 'IV & V' refers to Independent Verification and Validation.