Software Testing Fundamentals—Concepts, Roles, and Terminology

SOFTWARE TESTING—WHAT, WHY, AND WHO WHAT IS SOFTWARE TESTING?

1. Meets the business and technical requirements that guided its design and development, and
2. Works as expected.

Software testing also identifies important defects, flaws, or errors in the application code that must be fixed. The modifier "important" in the previous sentence is, well, important because defects must be categorized by severity (more on this later).

During test planning we decide what an important defect is by reviewing the requirements and design documents with an eye towards answering the question "Important to whom?" Generally speaking, an important defect is one that from the customer’s perspective affects the usability or functionality of the application. Using colors for a traffic lighting scheme in a desktop dashboard may be a no-brainer during requirements definition and easily implemented during development but in fact may not be entirely workable if during testing we discover that the primary business sponsor is color blind. Suddenly, it becomes an important defect. (About 8% of men and .4% of women have some form of color blindness.)

The quality assurance aspect of software development—documenting the degree to which the developers followed corporate standard processes or best practices—is not addressed in this paper because assuring quality is not a responsibility of the testing team. The testing team cannot improve quality; they can only measure it, although it can be argued that doing things like designing tests before coding begins will improve quality because the coders can then use that information while thinking about their designs and during coding and debugging.

Software testing has three main purposes: verification, validation, and defect finding.

♦ The verification process confirms that the software meets its technical specifications. A "specification" is a description of a function in terms of a measurable output value given a specific input value under specific preconditions. A simple specification may be along the line of "a SQL query retrieving data for a single account against the multi-month account-summary table must return these eight fields <list> ordered by month within 3 seconds of submission."

♦ The validation process confirms that the software meets the business requirements. A simple example of a business requirement is "After choosing a branch office name, information about the branch’s customer account managers will appear in a new window. The window will present manager identification and summary information about each manager’s customer base: <list of data elements>." Other requirements provide details on how the data will be summarized, formatted and displayed.

♦ A defect is a variance between the expected and actual result. The defect’s ultimate source may be traced to a fault introduced in the specification, design, or development (coding) phases.

WHY DO SOFTWARE TESTING?

"A clever person solves a problem. A wise person avoids it."

Why test software? "To find the bugs!" is the instinctive response and many people, developers and programmers included, think that that’s what debugging during development and code reviews is for, so formal testing is redundant at best. But a "bug" is really a problem in the code; software testing is focused on finding defects in the final product.

Here are some important defects that better testing would have found.

♦ In February 2003 the U.S. Treasury Department mailed 50,000 Social Security checks without a beneficiary name. A spokesperson said that the missing names were due to a software program maintenance error.

♦ In July 2001 a "serious flaw" was found in off-the-shelf software that had long been used in systems for tracking U.S. nuclear materials. The software had recently been donated to another country and scientists in that country discovered the problem and told U.S. officials about it.

♦ In October 1999 the $125 million NASA Mars Climate Orbiter—an interplanetary weather satellite—was lost in space due to a data conversion error. Investigators discovered that software on the spacecraft performed certain calculations in English units (yards) when it should have used metric units (meters).

♦ In June 1996 the first flight of the European Space Agency's Ariane 5 rocket failed shortly after launching, resulting in an uninsured loss of $500,000,000. The disaster was traced to the lack of exception handling for a floating-point error when a 64-bit integer was converted to a 16-bit signed integer.

Software testing answers questions that development testing and code reviews can’t.

♦ Does it really work as expected?

♦ Does it meet the users’ requirements?

♦ Is it what the users expect?

♦ Do the users like it?

♦ Is it compatible with our other systems?

♦ How does it perform?

♦ How does it scale when more users are added?

♦ Which areas need more work?

♦ Is it ready for release?

What can we do with the answers to these questions?

♦ Save time and money by identifying defects early

♦ Avoid or reduce development downtime

♦ Provide better customer service by building a better application

♦ Know that we’ve satisfied our users’ requirements

♦ Build a list of desired modifications and enhancements for later versions

♦ Identify and catalog reusable modules and components

♦ Identify areas where programmers and developers need training

WHAT DO WE TEST?

First, test what’s important. Focus on the "core functionality"—the parts that are critical or popular—before looking at the ‘nice to have’ features. Concentrate on the application’s capabilities in common usage situations before going on to unlikely situations. For example, if the application retrieves data and performance is important, test reasonable queries with a normal load on the server before going on to unlikely ones at peak usage times. It’s worth saying again: focus on what’s important. Good business requirements will tell you what’s important. Software testing is a process of verifying and validating that a software application or program

The value of software testing is that it goes far beyond testing the underlying code. It also examines the functional behavior of the application. Behavior is a function of the code, but it doesn’t always follow that if the behavior is "bad" then the code is bad. It’s entirely possible that the code is solid but the requirements were inaccurately or incompletely collected and communicated. It’s entirely possible that the application can be doing exactly what we’re telling it to do but we’re not telling it to do the right thing.

A comprehensive testing regime examines all components associated with the application. Even more, testing provides an opportunity to validate and verify things like the assumptions that went into the requirements, the appropriateness of the systems that the application is to run on, and the manuals and documentation that accompany the application. More likely though, unless your organization does true "software engineering" the focus will be on the functionality and reliability of application itself.

Testing can involve some or all of the following factors. The more, the better. ♦ Business requirements

♦ Functional design requirements

♦ Technical design requirements

♦ Regulatory requirements

♦ Programmer code

♦ Systems administration standards and restrictions

♦ Corporate standards

♦ Professional or trade association best practices

♦ Hardware configuration

♦ Cultural issues and language differences

WHO DOES THE TESTING?

Software testing is not a one person job. It takes a team, but the team may be larger or smaller depending on the size and complexity of the application being tested. The programmer(s) who wrote the application should have a reduced role in the testing if possible. The concern here is that they’re already so intimately involved with the product and "know" that it works that they may not be able to take an unbiased look at the results of their labors. 

Testers must be cautious, curious, critical but non-judgmental, and good communicators. One part of their job is to ask questions that the developers might find not be able to ask themselves or are awkward, irritating, insulting or even threatening to the developers. 

♦ How well does it work? 

♦ What does it mean to you that "it works"? 

♦ How do you know it works? What evidence do you have? 

♦ In what ways could it seem to work but still have something wrong? 

♦ In what ways could it seem to not work but really be working? 

♦ What might cause it to not to work well?

A good developer does not necessarily make a good tester and vice versa, but testers and developers do share at least one major trait—they itch to get their hands on the keyboard. As laudable as this may be, being in a hurry to start can cause important design work to be glossed over and so special, subtle situations might be missed that would otherwise be identified in planning. Like code reviews, test design reviews are a good sanity check and well worth the time and effort. 

Testers are the only IT people who will use the system as heavily an expert user on the business side. User testing almost invariably recruits too many novice business users because they’re available and the application must be usable by them. The problem is that novices don’t have the business experience that the expert users have and might not recognize that something is wrong. Testers from IT must find the defects that only the expert users will find because the experts may not report problems if they’ve learned that it's not worth their time or trouble.

Key Players and Their Roles
 

1. Business sponsor(s) and partners
                  ♦ Provides funding
                  ♦ Specifies requirements and deliverables
                  ♦ Approves changes and some test results
2. Project manager Plans and manages the project
3. Software developer(s)
                  ♦ Designs, codes, and builds the application
                  ♦ Participates in code reviews and testing
                  ♦ Fixes bugs, defects, and shortcomings
4. Testing Coordinator(s) Creates test plans and test specifications based on the requirements and functional, and technical documents 

Tester(s) Executes the tests and documents results  

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The Adventures of Sherlock Holmes 

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Shotcomings or Pitfalls of Traditional Waterfall approach

The essence of waterfall software development is that complex software systems can be built in a sequential, phase-wise manner where all of the requirements are gathered at the beginning, all of the design is completed next, and finally the master design is implemented into production quality software. This approach holds that complex systems can be built in a single pass, without going back and revisiting requirements or design ideas in light of changing business or technology conditions. It was first introduced in an article written by Winston Royce in 1970, primarily intended for use in government projects.
Waterfall equates software development to a production line conveyor belt.
“Requirements analysts” compile the system specifications until they pass the finished requirements specification document to “software designers” who plan the software system and create diagrams documenting how the code should be written. The design diagrams are then passed to the “developers” who implement the code from the design
Under the waterfall approach, traditional IT managers have made valiant efforts to craft and adhere to large-scale development plans. These plans are typically laid out in advance of development projects using Gantt or M.P.P (Microsoft Project Plan) or PERT charts to map detailed tasks and dependencies for each member of the development group months or years down the line. However, studies of past software projects show that only 9% to 16% are considered on-time and on-budget.

Up-front Requirements Analysis
What are requirements? From the stakeholder’s perspective, the requirements are the features and specifications of the system. Requirements define what developers are to build. For example, the system must have a web site with e-commerce capability that can handle 10,000 purchases per hour, or the system must be accessible 99.999% of the time.
One of the biggest problems with waterfall is that it assumes that all project requirements can be accurately gathered at the beginning of the project. In waterfall mode the first phase represents the requirements analysis phase of a software development project. Analysts slave for weeks or months compiling everything they can gleam about the proposed system into comprehensive
“Software Requirements Specification” (SRS) documents. Once finished, the SRS is sent over the fence to the designers while the requirements analysts go to work on the next project.
Imagine a scenario where you engage a software group to build a critical software system. Do you think you could provide every last detail the developers need to know right off the bat? I have yet to encounter such a customer and I am hard pressed to think I ever will. As a start, consider the areas that must be addressed: 

• Business rules and exceptions
• Scalability and concurrent user support
• Browser or OS support
• User roles and restrictions
• User interface standards. 

In fact, it is inevitable that attempts at up-front requirements specification will leave out some very important details simply because the stakeholders cannot tell developers everything about the system at the beginning of the project. This means that the requirements typically change outside of the requirements phase in the form of “change orders”, and in many waterfall projects this can be very costly. By virtue of a requirements change, the intricately planned design can be affected dramatically, which will in turn affect any implementation and test strategies. The cost of change in a waterfall project increases exponentially over time because the developer is forced to make any and all project decisions at the beginning of the project.
What if your business needs are still emerging and certain aspects of the system are rapidly changing or cannot be defined yet? Business climates and objectives often changrapidly, especially in today’s age of instant information. Can you afford to lock your business into a rigid long-term project where the cost of change grows exponentially? For example, a national test preparation organization commissioned my company to build a simulator for an upcoming standardized test. Since the test itself had not been released yet, the types of questions that would appear on the test were unknown when we started development. But the system had to be done shortly after the tests were released. Markets are forcing the software development community to respond with flexible development plans that flatten the cost of change.
People need to see and feel something before they really know what they want. The “I’ll Know it When I See It” (IKIWISI) law says that software development customers can better describe what they really want after seeing and trying working, functional software. I often use a “drawing” analogy to help explain this effect. Although I’m a terrible artist, when I draw a picture I need to see the drawing as I progress. If I tried to close my eyes and draw the same picture, it would prove far less successful. But this is what waterfall asks customers to do: specify the entire system without having a chance to periodically see the progress and make adjustments to the requirements as needed. Waterfall is an “over the fence” approach; the requirements are solicited from the user and some time later the finished product is presented to the user. This is entirely unnatural because customers find it difficult to specify software perfectly without seeing it evolve and progress.
The problem of undefined, changing, and emerging requirements presents a very large challenge to waterfall projects because by definition all requirements must be captured up-front at the risk of costly changes later.

The waterfall methodology assumes that up-front planning is enough to take into account all variables that could impact the development process. In fact, waterfall projects allocate copious effort detailing every possible risk, mitigation plan, and contingency. But is it possible to predict any and all variables that could possibly affect a software project? The empirical
answer is “no” considering the limited success of waterfall projects.

Waterfall therefore equates software development to an assembly line; defined processes can be established that, when used sequentially, result in a successful project each time. The first step is X, the second is Y, and the result is always Z.

Source: http://danube.com/docs/Intro_to_Agile.pdf