c# ean 13 barcode generator de Complete in C#.NET

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In addition to the formal test techniques, good programmers use a variety of less formal, heuristic techniques to expose errors in their code. One heuristic is the technique of error guessing. The term error guessing is a lowbrow name for a sensible concept. It means creating test cases based upon guesses about where the program might have errors, although it implies a certain amount of sophistication in the guessing. You can base guesses on intuition or on past experience. 21 points out that one virtue of inspections is that they produce and maintain a list of common errors. The list is used to check new code. When you keep records of the kinds of errors you ve made before, you improve the likelihood that your error guess will discover an error. The next few subsections describe specific kinds of errors that lend themselves to error guessing.

One of the most fruitful areas for testing is boundary conditions off-by-one errors. Saying num 1 when you mean num and saying >= when you mean > are common mistakes. The idea of boundary analysis is to write test cases that exercise the boundary conditions. Pictorially, if you re testing for a range of values that are less than max, you have three possible conditions:

As shown, there are three boundary cases: just less than max, max itself, and just greater than max. It takes three cases to ensure that none of the common mistakes has been made. The example on page TBD contains a test for m_employee[ ID ].governmentRetirementWithheld > MAX_GOVT_RETIREMENT. According to the principles of boundary analysis, three cases should be examined:

Case 1 Test Description Case 1 is defined so that the true boolean condition for m_employee[ ID ]. governmentRetirementWithheld < MAX_GOVT_RETIREMENT is the true side of the boundary. Thus, the Case 1 test case sets m_employee[ ID ].governmentRetirementWithheld to MAX_GOVT_RETIREMENT

1. This test case was already generated. 3 Case 3 is defined so that the false boolean condition for m_employee[ ID ]. governmentRetirementWithheld < MAX_GOVT_RETIREMENT is the false side of the boundary. Thus, the Case 3 test case sets m_employee[ ID ].governmentRetirementWithheld to MAX_GOVT_RETIREMENT + 1. This test case was also already generated. An additional test case is added for the dead-on case in which m_employee [ ID ].governmentRetirementWithheld = MAX_GOVT_RETIREMENT.

Boundary analysis also applies to minimum and maximum allowable values. In this example, it might be minimum or maximum grossPay, companyRetirement, or PersonalRetirementContribution, but since calculations of those values are outside the scope of the routine, test cases for them aren t discussed further here. A more subtle kind of boundary condition occurs when the boundary involves a combination of variables. For example, if two variables are multiplied together, what happens when both are large positive numbers Large negative numbers 0 What if all the strings passed to a routine are uncommonly long In the running example, you might want to see what happens to the variables totalWithholdings, totalGovernmentRetirement, and totalRetirement when every member of a large group of employees has a large salary say, a group of programmers at $250,000 each. (We can always hope!) This calls for another test case:

Case 11 Test Description A large group of employees, each of whom has a large salary (what constitutes large depends on the specific system being developed), for the sake of example we ll say 1000 employees each with a salary of $250,000, none of whom have had any social security tax withheld and all of whom want retirement withholding.

A test case in the same vein but on the opposite side of the looking glass would be a small group of employees, each of whom has a salary of $0.00.