1. Testing

2. Activity 1
5 mins
What is the difference between: A “Syntax Error” …and… A “Logic Error”

3. Testing Introduction Computers only do what they are told.
Learning Objectives:
(p) describe syntax errors and logic errors which may occur while developing a program
(q) understand and identify syntax and logic errors
(r) select and justify test data for a program, stating the expected outcome of each test.
Introduction
Computers only do what they are told.
If the program doesn’t work as it should (either doesn’t run or runs with unexpected results) it will be down to an error that the programmer has made.
We will now look at the two types of errors found in programming and understand how we can test for these errors so that our programs work as we have intended.

4. Syntax Error Logic Error
Testing
Learning Objectives:
(p) describe syntax errors and logic errors which may occur while developing a program
(q) understand and identify syntax and logic errors
(r) select and justify test data for a program, stating the expected outcome of each test.
There are 2 types of error:
Syntax Error
&
Logic Error
What do you think is the difference?

5. Testing HOW? Syntax Errors:
Learning Objectives:
(p) describe syntax errors and logic errors which may occur while developing a program
(q) understand and identify syntax and logic errors
(r) select and justify test data for a program, stating the expected outcome of each test.
Syntax Errors:
These are errors that occur when the instructions/code that is written do not follow the rules of the programming language.
The code cannot be understood by the computer when it is run and an error message is generated.
Most of the time the IDEs interpreter will highlight these errors as you type your code.
HOW?
Often with red lines!

6. Testing
Learning Objectives:
(p) describe syntax errors and logic errors which may occur while developing a program
(q) understand and identify syntax and logic errors
(r) select and justify test data for a program, stating the expected outcome of each test.
Syntax Errors:
Now that you are proficient programmers, what syntax errors have you experienced?
Examples may include:
Syntax Error
Example
Misspelt Keywords
“colour” instead of “color”
Missing or extra brackets
print(“Hello World”))
Missing parts from multi-line instructions
Missing the ENDWHILE from WHILE/ENDWHILE
Type mismatch errors
Trying to multiply a string variable
Referring to variables that have not been declared
If x == 3:
(when x is unknown)

7. Testing Logic Errors: Learning Objectives:
(p) describe syntax errors and logic errors which may occur while developing a program
(q) understand and identify syntax and logic errors
(r) select and justify test data for a program, stating the expected outcome of each test.
Logic Errors:
These types of error are usually not known until runtime (when the program is actually being used).
They occur when there is a mistake in the algorithm which results in the program not doing what it was intended to do.
The program might:
Crash
Get stuck in a loop
Or simply produce unexpected results.
What sort of things might happen if a program contains some logic errors?

8. Testing
Learning Objectives:
(p) describe syntax errors and logic errors which may occur while developing a program
(q) understand and identify syntax and logic errors
(r) select and justify test data for a program, stating the expected outcome of each test.
Logic Errors:
Now that you are proficient programmers, what logic errors have you experienced?
Examples may include:
Logic Error
Mistakes in maths (eg: x*(3+2), instead of (x*3)+2)
Misplaced brackets
Misplaced indentations
Instructions in the wrong order
Wrong conditions being set in a loop

9. Testing using Test Plans!
Learning Objectives:
(p) describe syntax errors and logic errors which may occur while developing a program
(q) understand and identify syntax and logic errors
(r) select and justify test data for a program, stating the expected outcome of each test.
After writing your code, correcting syntax errors as we go along and checking that our program works as it should by systematically testing it as we go along, our program should be working well!
But this is often not the case as we are humans and humans make mistakes!
So how can we check for these remaining errors?
The answer is…
Testing using Test Plans!

10. Testing
Learning Objectives:
(p) describe syntax errors and logic errors which may occur while developing a program
(q) understand and identify syntax and logic errors
(r) select and justify test data for a program, stating the expected outcome of each test.
Test Plans:
Test plans are used to interrogate the finished program.
Testing is done using test data and a good test plan will use test data that covers every possible type of input:
Normal Data
Borderline / Extreme Data
Erroneous Data

11. Testing Normal Data Learning Objectives:
(p) describe syntax errors and logic errors which may occur while developing a program
(q) understand and identify syntax and logic errors
(r) select and justify test data for a program, stating the expected outcome of each test.
Normal Data
This is data that should be accepted by the program.
Normal input you would expect form typical use.
E.G. Date of Birth = 12/04/1972

12. Testing Borderline / Extreme Data Learning Objectives:
(p) describe syntax errors and logic errors which may occur while developing a program
(q) understand and identify syntax and logic errors
(r) select and justify test data for a program, stating the expected outcome of each test.
Borderline / Extreme Data
Data that tests the limits of what should be accepted
Data just above, just below and actually on the acceptable limit
E.G. Date of Birth = 12/04/1900

13. Testing Erroneous Data Learning Objectives:
(p) describe syntax errors and logic errors which may occur while developing a program
(q) understand and identify syntax and logic errors
(r) select and justify test data for a program, stating the expected outcome of each test.
Erroneous Data
Data that should be rejected
Also check that error messages are generated to inform the user
E.G. Date of Birth = Twelfth of the fourth nineteen seventy two
Error: please enter a valid date!

14. Testing Test Plans Learning Objectives: These are used to:
(p) describe syntax errors and logic errors which may occur while developing a program
(q) understand and identify syntax and logic errors
(r) select and justify test data for a program, stating the expected outcome of each test.
Test Plans
These are used to:
ensure that a system is fully tested
to document the outcomes.
Test plans are made up of:
The test data
The reason for the test
The expected outcome
The actual result (which is added later – after development)

15. Testing Actual Outcomes (after development) Learning Objectives:
(p) describe syntax errors and logic errors which may occur while developing a program
(q) understand and identify syntax and logic errors
(r) select and justify test data for a program, stating the expected outcome of each test.
Test Plans
Ultimately they will test the program works as it should – has met the success criteria.
So if the success criteria was:
A suitable test plan might look something like this:
Example Success Criteria:
User should be able to enter ONLY dice number 4, 6 or 12
Program should generate a random number within the limits of the dice chosen.
The program should ask if the user would like to roll again.
Test Number
Reason for Test
Type of Test
Test Data
Expected Outcome 1
To see if the user can input their dice number
Typical
Enter a 6 when program requests
The program will accept the input and pick a random number from 1-6. 2
Extreme
Enter a 12 when program requests
The program will accept the input and pick a random number from 1-12. 3
Erroneous
Enter a 1 when program requests
The program will NOT accept the input and ask for the number again. 4
To see if the user can roll again.
Type in “Y”
The program will ask the user for a dice number again. 5
Type in “N”
The program close. 6
Type in “Yes”
The program will ask the user if they would like to roll again.
Actual Outcomes (after development)