24 Random & Dynamic Test Data

Learning Objectives

• Function in Programming

• Test Execution Side Effects

• Add dynamic to test data, using random number, timestamp

• Use of Faker test data generation library

Knowledge Point: Function

A function is a sequence of program instructions that performs a specific task.

Function in Coding

Let’s do a simple exercise. Create a text file with name minus.rb with the content below:

# definition of a function
def minus(a, b)
  a - b
end

# use of the function
minus(10, 2) 

To run it from the command line:

> ruby minus.rb

There is no output, as we didn’t print it out. Change the last line.

puts minus(10, 2)

Run the program (minus.rb) again:

> ruby minus.rb
8

The output is not clear. We could add some text to make the output “The result is: 8”.

The code below will return an error.

puts "The result is: " + minus(10, 2)

The error is:

minus.rb:5:in `+': no implicit conversion of Integer into String (TypeError)

puts "The result is: " + minus(10, 2)
                         ^^^^^^^^^^^^
	from minus.rb:5:in `<main>'

This is because adding an integer to a String is not allowed. A simple solution:

puts "The result is: #{ minus(10, 2) }"

You can understand this way: `#{ code }` returns a string.

Knowledge Point: Test Execution Side Effects

We introduced the concept in the last episode (#23). Let’s explore this further with the example of CRUD tests. For example, adding a professional test (with the same name) is wrong for test automation: the second test execution onwards would fail.