SilkTest User's Guide: Debugger

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Debugger - Tips on debugging

<< Debugger - Running, resetting, and terminating execution | Debugger - Designing and testing with debugging in mind >>

User's Guide

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Tips on debugging

To check that a variable has a reasonable value on entry to a function, set a
breakpoint on the line that calls the function and use the command View/
Global Variables to check the variable's value.

Uninitialized variables

SilkTest does not initialize variables for you. So if you have not initialized a
variable on entry to a function, it will have the value <unset>. It is better to
explicitly give a value to a variable than to trust that another function has
already initialized it for you. Also, remember that 4Test does not keep local
variables around after a function exits; the next time the function is called, its
local variables could be uninitialized.

If you are in doubt about whether a variable has a reasonable value at a
particular point, set a breakpoint there and use View/Global Variables or
View/Local Variables to check the variable's value.

Global and local
variables with the
same name

It is usually not good programming practice to give different variables the
same names. If a global and local variable with the same name are in scope
(accessible) at the same time, your code can only access the local variable.

To check for repeated names, use View/Local Variables and View/
Global Variables to see if two variables with the same name are in scope
simultaneously.

Incorrect values for
loop variables

When you write a for loop or a while loop, be sure that the initial, final, and
step values for the variable that controls the loop are correct. Incrementing a
loop variable one time more or less than you really want is a common source
of errors.

To make sure a control loop works as you expect, use Debug/Step Into to step
through the execution of the loop one statement at a time, and watch how the
value of the loop variable changes using View/Local Variables.

Checking the
precedence of
operators

The order in which 4Test applies operators when it evaluates an expression
may not be what you expect. Use parentheses, or break an expression down
into intermediate steps, to make sure it works as expected. You can use View/
Expression to evaluate an expression and check the result.

Incorrect use of break
statements

A break statement transfers control of the script out of the innermost nested
for, for each, while, switch, or select statement only. In other words, break
exits from a single loop level, not from multiple levels. Use Debug/Step Into
to step through the script one line at a time and ensure that the flow of control
works as you expect.

Infinite loops

To check for infinite loops, step through the script with Debug/Step Into.

Code that never
executes

To check for code that never executes, step through the script with Debug/
Step Into.