09 Error handling and testing

Question 1

How do we minimise the number of bugs and user mistakes in our program?

Answer 1

Careful engineering of a program
Error checking
Extensive automated testing

Question 2

How do modern softwares run tests on programs?

Answer 2

Continuous integration
Suite of tests run every time a change is made to the code

Question 3

What are the two types of program errors?

Answer 3

Syntax errors
Exceptions

Question 4

Syntax errors

Answer 4

Syntax does not conform to the rules of the language
Easy to detect as interpreter/compiler will print an error

Question 5

Exceptions

Answer 5

Something unexpected or anomalous occurs when executing a program

Question 6

What are some examples of exceptions

Answer 6

• Attempting to divide by 0
• Receiving negative data when only positive data is permitted
• Unexpected integer overflow
• Attempting to compute the dot product between vectors of different lengths

Question 7

Raising/ Throwing an exception

Answer 7

Trigger an exception

Question 8

Parameter validity checking

Answer 8

Adding checks to parameter so we do not compute completely wrong answer
if r <= 0:
raise ValueError(“Distance r must be greater than zero”)

Question 9

Why is testing important

Answer 9

Enhances program quality
Building confidence in programming