The test log should be prepared by the person executing the tests. It is a diary of the events that take place during the test. It supports the concept of a test as a repeatable experiment [14]. In the experimental world of engineers and scientists detailed logs are kept when carrying out experimental work. Software engineers and testing specialists must follow this example to allow others to duplicate their work.

The test log is invaluable for use in defect repair. It gives the developer a snapshot of the events associated with a failure. The test log, in combination with the test incident report which should be generated in case of anomalous behavior, gives valuable clues to the developer whose task it is to locate the source of the problem. The combination of documents helps to prevent incorrect decisions based on incomplete or erroneous test results that often lead to repeated, but ineffective, test-patch-test cycles.