A negative test is when you put in an invalid input and receive errors.

A positive test is when you put in a valid input and expect some action to be completed in accordance with the specification.

There are four types of severity ratings as shown in the table:

• Severity 1 (showstoppers): These kinds of defects do not allow the application to move ahead. So they are also called showstopper defects.
• Severity 2 (application continues with severe defects): Application continues working with these types of defects, but they can have high implications, later, which can be more difficult to remove.
• Severity 3 (application continues with unexpected results): In this scenario the application continues but with unexpected results.
• Severity 4 (suggestions): Defects with these severities are suggestions given by the customer to make the application better. These kinds of defects have the least priority and are considered at the end of the project or during the maintenance stage of the project.

Exploratory testing is also called adhoc testing, but in reality it's not completely adhoc. Ad hoc testing is an unplanned, unstructured, may be even an impulsive journey through the system with the intent of finding bugs. Exploratory testing is simultaneous learning, test design, and test execution. In other words, exploratory testing is any testing done to the extent that the tester proactively controls the design of the tests as those tests are performed and uses information gained while testing to design better tests. Exploratory testers are not merely keying in random data, but rather testing areas that their experience (or imagination) tells them are important and then going where those tests take them.

As the name suggests they are tables that list all possible inputs and all possible outputs. A general form of decision table is shown in the following figure.



Condition 1 through Condition N indicates various input conditions. Action 1 through Condition N are actions that should be taken depending on various input combinations. Each rule defines unique combinations of conditions that result in actions associated with that rule.