Functional Test Refactoring: Extract Function

Extract a set of test steps performing a common user operation to a reusable function

This is the 1st of 6 Functional Test Refactorings: Extract Function. I will show each refactoring in the following sections:

• Motivation, Why?

• Mechanics, How?

• Refactoring Steps, step by step in TestWise IDE

• Sample test scripts (before and after)

• Demonstration (animated GIF, easier to follow the core steps)

• Demonstration (video, easier to get a flow of actions)

• Benefits

• Exercises

You may start with any section.

I strongly recommend you do this refactoring exercise (the one demonstrated and the extras). Once you have mastered the concept, performing refactorings is quick, usually in seconds. To help you get into action quickly, I prepared the test project on Github (available for free).

> cd my-working-dir
> git clone https://github.com/testwisely/agiletravel-ui-tests

The test project is at my-working-dir/agiletravel-ui-tests/pre-refactoring .

While the demonstration is shown in TestWise IDE (created by me), you may use TestWise (in free mode) to do the exercise or use your own preferred tool.

Tip: if you make mistakes and are unable to figure out what to do, reset the test project using Git.

> cd my-working-dir
> git checkout -f

Motivation (Extract Function)

You have long logically grouped test steps to perform a common operation.

For well-understood operations such as user login and credit card payment (formed with a set of individual test steps), it is better to replace them with a reusable function.

Sample Test (before)
The test script file in the sample project: spec/login_spec.rb

it "User can sign in OK" do
  driver.find_element(:id, "username").send_keys("agileway")
  driver.find_element(:id, "password").send_keys("testwise")
  driver.find_element(:xpath,"//input[@value='Sign in']").click
  # ...
end

Issues with the test

• The three test steps (enter username, enter password, click ‘Sign in’) will be used very frequently in many test scripts. Copy-n-Paste is not only inefficient, but more importantly, it is also hard to maintain. Imagine changing the test user name, the ‘Sign in’ button, …, etc. If that happens, you need to update many files.

• Not very readable for this most common user operation.

Action

Extract these test steps in a reusable function.

Scope

The test script file.

Mechanics

1. Identify test steps that are reusable for a common operation, e.g., login

2. Select the test steps

3. Extract them into a function, give a meaningful name

4. Replace the original steps with a call to the function

5. Run all the test cases that have been changed

Refactoring Steps in TestWise

1. Select the test steps

2. Invoke the refactoring

3. Enter a function name

4. Adjust parameters if necessary (TestWise will analyze the test steps and pre-determine the parameters)

5. Preview the new function

6. Apply the refactoring

Extract Function Dialog

A dialog window appears after invoking the ‘Extract Function’ refactoring (with selected test steps). The test engineer may

• enter the function name (as the example shown on the right)

• edit (add or remove or change) parameters for the function

• edit the previewed function directly

Extract Function Dialog

Click the “OK” button to apply the refactoring

Expected Result

• A new function with the supplied name is inserted in the test scripts, containing the selected test steps

• The test steps in the test case are replaced with a call to the new function

Sample Test (after)

def login(username, password)
  driver.find_element(:id, "username").send_keys(username)
  driver.find_element(:id, "password").send_keys(password)
  driver.find_element(:xpath,"//input[@value='Sign in']").click
end

it "User can sign in OK" do
  login("agileway", "testwise")
  # ...
end

Demonstration (animated GIF)

1. Invoke Refactoring via the menu

   

2. Invoke Refactoring via the keyboard shortcut
   As we need to perform refactorings frequently, I suggest using keyboard shortcuts for efficiency (Ctrl + Alt + M on Windows).

   

Demonstration (Video)

1. Extract login function (multiple steps) via the menu (19s)

2. Extract logoff function (single step) via keyboard shortcut (6s)

Benefits

• Concise and Reusable

• DSL (Domain Specific Language)
  You can define your own function name that is meaningful to your team, such as login, login_as, sign_in

• Reduce Duplication, DRY
  In the case of our example, if there are changes to the login page, you will only need to update the function definition once, regardless of how many tests you have.

Exercises

1. Perform ‘Extract Function’ refactoring to create login function (or using your preferred name) in login_spec.rb (as shown)

2. Use the new login function in the second test case

3. Perform another ‘Extract Function’ refactoring to create logoff function

Related Refactorings

• Move to Helper

• Extract to Page Function

This article is an excerpt from my book “Practical Web Test Automation”.