Notes

Testing code is the process of running a computer program to identify problems.

The first stage of testing a software program code is performed by the company that developed the software or the programmer who wrote the program. The software is tested by running sets of test data through it. These data sets generally contain values that push the software to extremes.

The next stage of testing is called beta testing, which is done by beta testers – volunteer users who agree to work with the prerelease, or beta, version of the program and alert the programmers about errors they encounter. These early users agree to report any problems they see in exchange for the chance to be among the first to take advantage of the new features in an upcoming version of software. Testing code is essential because users rely on the program to work properly. They expect software to run without interruptions or problems, and to return accurate results.

Most code has at least a few mistakes, no matter how diligent programmers are while writing it. It is up to software developers to identify and fix those mistakes before anyone relies upon the program’s results. Bugs are errors in a computer program.

Bugs fall into three categories:

Syntax errors, where the programming language usage rules were not followed

Semantic errors, where the programmer misunderstood something in the programming language

Logic errors, where a mathematical calculation in the program code was incorrect Software program bugs can result in a number of outcomes that indicate problems. Examples of problems caused by bugs include:

a report that will not print.

a sum that is incorrect.

a list that contains the wrong names.

a program that halts while running. The new software program code must be compiled, which means that it must be translated into a machine language.

Syntax errors, which are mistakes in programming language usage, are found during the initial run of the code through the compiler software that translates code into machine language.

Compilers have a stepping function that runs code line by line, to help developers find bugs. Suppose you are developing a program that calls for the days of the workweek to be an integral part of its calculations. It is important that the dates entered fall on Monday, Tuesday, Wednesday, Thursday, or Friday. The program also may be required to only accept days that are not federal holidays.

To test the code for this program, a number of dates are entered. Some dates have not occurred yet, while others fall on a Saturday or Sunday. Still other dates are federal holidays.

The test is to see if the program can calculate whether the dates are the desired input and reject the dates that are not. Ideally, there will be warnings or error messages that appear when an incorrect date is input. Debugging is the process of identifying bugs in computer software.

Debugging software programs can help with this process and run the software one step at a time to examine the contents of the programs code, which can illuminate errors.

Debugging is an iterative, or repetitive, process, meaning the steps may need to be taken repeatedly. Debugging can occur throughout the testing and fixing process, because new errors may be discovered or introduced as existing errors are fixed. Many integrated development environments (IDEs) include debugging software that allow a programmer to investigate the source of an error by:

stepping through the program line by line.

establishing breakpoints, which means to run the code from one selected point to another, and to manage the testing of the program in segments.

watching where the data is stored in program memory to ensure that the correct values are being calculated or captured Suppose you are developing a program that calls for the days of the workweek to be an integral part of its calculations. It is important that the dates entered fall on Monday, Tuesday, Wednesday, Thursday, or Friday. The program also may be required to only accept days that are not federal holidays.

To test the code for this program, a number of dates are entered. Some dates have not occurred yet, while others fall on a Saturday or Sunday. Still other dates are federal holidays.

You then must run your program using the debugger software, which will:

step through the program line by line.

watch where the data is stored in program memory to ensure the correct values are being calculated or captured.

Ideally, warnings or error messages will appear when an incorrect date is input. You also can trace some errors by checking where the data is stored in the program. Fixing computer code is the process of correcting errors. It may be as simple as fixing a misspelled command or as complex as rethinking the logic of a key segment of the code.

Whatever is involved, the idea is to fix the code – to enter new code that performs as intended in the place of the old code that produced an error It is not enough to fix errors in code. You also must verify the fixes by retesting the code. Otherwise, you cannot be sure that the new code has corrected the original error without introducing a new error Testing software code is an iterative process. This means you will go through the steps in the process as many times as it takes until the outcome is the one you desire.

The testing cycle is a process involving:

1. Reproducing and diagnosing the error

2. Making a fix

3. Testing the fixed code Each time a change or fix is made, the code must be tested again to ensure that no new errors have been introduced.

If a new error appears, the testing cycle is initiated again.

The goal is error-free code. After performing a code fix, a software developer must verify that the new code has fixed the error, and has not caused another error.

To ensure this, the program must be tested again. This is why the testing process is referred to as the testing cycle. It is an iterative process that is complete only when the results are what the programmer intended. Fixing code involves correcting any errors found during testing and debugging. To diagnose an error, it first must be reproduced.

Once the source of an error is identified, the programmer can examine the error and determine what is causing it. Then, new code can be put in its place. Programmers test code by running sets of test data through the software. The data sets generally contain values that push the program to extremes.

The next state of testing is beta testing, which is done by beta testers who report any problems using the program.

Debugging software also is used to run the program and identify any errors that need to be fixed. A value represents content in a computer program that is returned by a function; it is the result of a function. The value remains the same in the computer’s memory unless the programmer changes it.

A variable is a component or symbol in a computer program to which a programmer assigns a value or a set of values.

Variables store values or sets of values.

Example: A programmer who is developing a database for a store that includes customers’ names and addresses may assign values to the variables to represent:

firstName = first name

lastName = last name

fullName = full name

The full equation might read

“firstName + lastName = fullName. Variables are useful to programmers because:

Variables can store temporary data.

Variables are flexible. They can store values of different data types, which may include numeric or alphanumeric values; character strings, which are linear sequences of alphanumeric characters; or memory addresses composed of numeric indicators, which are identifiers for memory locations.

Code with variables is easier to reuse and therefore reduces the amount of coding required. In programming, variables have these properties:

The name is the label or identifier the programmer assigns to a variable.

The extent of a variable is a description of the variable’s beginning and ending in time. The extent is the time in which the variable is available.

Scope is the spatial location of a variable. A variable is either global or local in scope.

A global variable is accessible from anywhere during the entire time the program is running.

A local variable is accessible only in a specific region of a program or within a declared function. In programming, variables can be defined as:

Scalar: This is a single number or value that may include an integer, a floating-point decimal, or a string of characters.

Array: This is a group of related scalar or individual values assembled into one new entity, such as a sequence of numbers or letters.

User-defined types (UDTs): This is a data type in which programmers assign their own true or false values to the data type, such as a schedule where all work and school entries are “true” and all leisure activities are “false.”

Abstract data types (ADTs): This is a data type in which multiple values are assigned to a single data type, such as a single course entry in a class syllabus, composed of the course name, number, and description. A data type is the kind of value that a variable can hold. Each data type has unique characteristics and stores data in a specific way.

The most common data types are:

Alphanumeric strings: mixed sequences of letters and numbers

Boolean operators: variables that can hold one of two values — true or false

Characters: individual letters, numbers, or symbols

Floating point numbers: moveable decimal points in a number, rather than fixed (in other words, the location of the decimal point and the number of decimal places can change)

Integers: numeric whole-number values, either positive or negative, that do not have decimal points A subroutine is a block of code that can be used in multiple places and does a specific task. This allows the programmer to save time by not having to rewrite the code multiple times. The term subroutine may be used to refer to a procedure, function, routine, method, or subprogram.

Subroutines can contribute to excess use of the computer’s resources, known as computational overhead, because they are independent of the main code. One pass of the coding sequence is called an iteration.

Programmers can use less code and save on performing repetitive tasks by using iteration. Rather than writing a print statement one hundred times to output numbers 1 through 100, a programmer can use an iteration statement to do the work in two lines of code.

Iteration in computer programming saves time and resources and can help programmers identify errors in coding logic or entered data. Integrated Development Environments (IDEs) are coordinated software program-writing packages. IDEs provide software developers with interactive programming tools and a work environment in which to use them. In the past, programmers wrote programs using multiple and separate software application tools. Now these tools come in an integrated package. Programmers use an IDE to write software programs, because:

it simplifies the process by providing a single user interface for multiple software tools.

it enables programmers to see errors and automate repetitive tasks.

it provides a common source for writing and linking code. IDEs usually include several key tools for writing, building, and correcting a program, such as:

source code editor – Also called the text editor, this tool is used to write, modify, and save code. This is the main tool for a programmer.

build automation – A software tool that helps the programmer construct, or build, a program by writing directions for a variety of repetitive tasks. compiler – A tool that translates the programming language, such as Java, into a machine language that the computer can run. It can also be used in debugging a program.

interpreter – A tool that translates the programming language into machine language for the computer without its being compiled. Some IDEs contain both a compiler and an interpreter.

debugger – A tool used to test a program one step at a time to find and fix errors. Testing code is the process of running a computer program to identify problems.

The first stage of testing a software program code is performed by the company that developed the software or the programmer who wrote the program. The software is tested by running sets of test data through it. These data sets generally contain values that push the software to extremes.

The next stage of testing is called beta testing, which is done by beta testers – volunteer users who agree to work with the prerelease, or beta, version of the program and alert the programmers about errors they encounter. These early users agree to report any problems they see in exchange for the chance to be among the first to take advantage of the new features in an upcoming version of software. Testing code is essential because users rely on the program to work properly. They expect software to run without interruptions or problems, and to return accurate results.

Most code has at least a few mistakes, no matter how diligent programmers are while writing it. It is up to software developers to identify and fix those mistakes before anyone relies upon the program’s results. Bugs are errors in a computer program.

Bugs fall into three categories:

Syntax errors, where the programming language usage rules were not followed

Semantic errors, where the programmer misunderstood something in the programming language

Logic errors, where a mathematical calculation in the program code was incorrect Software program bugs can result in a number of outcomes that indicate problems. Examples of problems caused by bugs include:

a report that will not print.

a sum that is incorrect.

a list that contains the wrong names.

a program that halts while running. Software program bugs can result in a number of outcomes that indicate problems. Examples of problems caused by bugs include:

a report that will not print.

a sum that is incorrect.

a list that contains the wrong names.

a program that halts while running.
The new software program code must be compiled, which means that it must be translated into a machine language.

Syntax errors, which are mistakes in programming language usage, are found during the initial run of the code through the compiler software that translates code into machine language.

Compilers have a stepping function that runs code line by line, to help developers find bugs
Suppose you are developing a program that calls for the days of the workweek to be an integral part of its calculations. It is important that the dates entered fall on Monday, Tuesday, Wednesday, Thursday, or Friday. The program also may be required to only accept days that are not federal holidays.

To test the code for this program, a number of dates are entered. Some dates have not occurred yet, while others fall on a Saturday or Sunday. Still other dates are federal holidays.

The test is to see if the program can calculate whether the dates are the desired input and reject the dates that are not. Ideally, there will be warnings or error messages that appear when an incorrect date is input. Debugging is the process of identifying bugs in computer software.

Debugging software programs can help with this process and run the software one step at a time to examine the contents of the programs code, which can illuminate errors.

Debugging is an iterative, or repetitive, process, meaning the steps may need to be taken repeatedly. Debugging can occur throughout the testing and fixing process, because new errors may be discovered or introduced as existing errors are fixed. Many integrated development environments (IDEs) include debugging software that allow a programmer to investigate the source of an error by:

stepping through the program line by line.

establishing breakpoints, which means to run the code from one selected point to another, and to manage the testing of the program in segments.

watching where the data is stored in program memory to ensure that the correct values are being calculated or captured. Suppose you are developing a program that calls for the days of the workweek to be an integral part of its calculations. It is important that the dates entered fall on Monday, Tuesday, Wednesday, Thursday, or Friday. The program also may be required to only accept days that are not federal holidays.

To test the code for this program, a number of dates are entered. Some dates have not occurred yet, while others fall on a Saturday or Sunday. Still other dates are federal holidays.

You then must run your program using the debugger software, which will:

step through the program line by line.

watch where the data is stored in program memory to ensure the correct values are being calculated or captured.

Ideally, warnings or error messages will appear when an incorrect date is input. You also can trace some errors by checking where the data is stored in the program. (What is the name of a coding sequence that is executed multiple times in a program? correct anwser: a loop)