PPT1: How failures come to be CEN 4072 Software Testing PPT1: How failures come to be PPT and video are due: no later than August 31, 5:00 PM Submit to: lpiegl@gmail.com This template file is just an outline of the presentation that you need to complete. Additional pages will be necessary to fully explore the topic above. Each page should contain adequate text as well as illustrations. You are free to use all publically available information (text as well as graphics) as long as the sources are properly acknowledged.

Team members’ contributions Member [name]:

Golden rules Content outline: Software testing begins with careful design Explanation and examples

Golden rules Content outline: Software that cannot be tested is useless Explanation and examples

Facts on debugging Content outline: Examples of software failures Impacts of software failures

Facts on debugging Content outline: Damages caused by software failures Impacts on society

Facts on debugging Content outline: Facts on debugging Costs, validation and improvements

The TRAFFIC principle Content outline: Track Reproduce Automate Find origins Focus Isolate Correct

From defect to failure Content outline: A sequence of events causing the defect to become a failure Explanation and illustration

Efficiency of testing Content outline: How defects and failures are related? Can testing show the absence of errors?

Efficiency of testing Content outline: How infections and defects are related? Explanation and illustration

Search in time and space Content outline: Search from defect to failure in time and space Illustration and explanation

Search in time and space Content outline: Find transition from sane to infected Illustration and explanation

Search in time and space Content outline: Search from defect to failure: the principles Examples of the complexity (number of variables and references among them)

Sample program - main int main(int argc, char *argv[]) { int *a; int i; a = (int *)malloc((argc - 1) * sizeof(int)); for (i = 0; i < argc - 1; i++) a[i] = atoi(argv[i + 1]); shell_sort(a, argc); printf("Output: "); printf("%d ", a[i]); printf("\n"); free(a); return 0; }

Sample program - sort There is a bug somewhere (main or static void shell_sort(int a[], int size) { int i, j; int h = 1; do { h = h * 3 + 1; } while (h <= size); h /= 3; for (i = h; i < size; i++) int v = a[i]; for (j = i; j >= h && a[j - h] > v; j -= h) a[j] = a[j - h]; if (i != j) a[j] = v; } } while (h != 1); There is a bug somewhere (main or shellsort). Find it using the principles below.

Find origins Content outline: Deduce value origins Separate relevant from irrelevant

Search in time Content outline: Observe a transition from sane to infected Example

Observing a run Content outline: Trace the execution for all variables for all steps of execution Illustration in time and space

Specific observations Content outline: Observe the state at specific locations Walk-through example

Specific observations Content outline: Find the transition from sane to infected Example steps

Specific observations Content outline: Fix the defect Regress or not to regress?

Finding causes Content outline: Find the difference between infected and sane states Search in time and space

Automated debugging: program slices Content outline: Separate the part of the program that is relevant to the failure Explanation and illustration

Automated debugging: observing state Content outline: Stop the program to observe the entire state Is this an option for large programs?

Automated debugging: watching state Content outline: Watch a part of the state to find changes during execution Examples and usefulness

Automated debugging: assertions Content outline: Specify expected values and check for them Do we really know the expected values?

Automated debugging: anomalies Content outline: What is an anomaly? Examples

Automated debugging: anomalies Content outline: Observe the difference between passing the failing runs Would this help with anomalies?

Automated debugging: cause-effect chains Content outline: How many chains are there? Is it reasonable to find THE cause-effect chain?

Automated debugging: cause-effect chains Content outline: Identify which variable caused the failure Note: causes are not necessarily errors!

Automated debugging: simplified input Content outline: Simplify the input so that each part contributes to the failure