Testing Databases

Objectives

This lesson covers the following objectives:

• Develop and apply a strategy for testing that a database functions as designed

Purpose

• Most people, when they buy a car, wish to know that it is reliable and will not break down.
• So the manufacturers will put the car through a number of tests before it is available to be sold.
• The same is true of a database; before it is sold to a customer, it is tested to verify that it meets the business requirements.

Unit Testing

• If two things are tested at once and the test fails, it is difficult or impossible to work out what has caused the failure.
• So it is important to test only one thing at a time.
• This is commonly referred to as unit testing.

What Could Be Tested?

• When testing a database, a variety of things need to be tested.
• For example:
  • Columns should be tested that they contain the correct data type.
  • Columns should be tested that they can accommodate the largest amount of data that might be entered.
  • Constraints should be checked that they only constrain or limit data that they are supposed to—no more and no less.

What Should Be Tested?

• It is frequently unrealistic to test every column and every constraint in every table in a database if it is a large database.
• A random spread of tests, that check some columns and some constraints, should be carried out.

Designing Tests

• Before you carry out a test, you should have a good idea of what result you expect to see if the database is
• working as expected.
• This should be documented before you carry out the test in a table similar to the one shown:

Running Tests

• Once you have designed your test, you can run it and record your results.

Terminology

Key terms used in this lesson included:

• Testing
• Unit Testing

Summary

In this lesson, you should have learned how to:

• Develop and apply a strategy for testing that a database functions as designed