Stop 06 · Programming Fundamentals for AutomationTopics · 9/10

Reading & Writing Test Scripts

In short

On day one at a job, you'll read far more test code than you write. A clean test is one a new teammate can understand in thirty seconds.

Applying everything from this phase together — writing clean, readable test scripts and being able to understand and modify scripts written by someone else, a daily skill in any automation role.

The purple blob in a lab coat writes in a journal next to a rack of coloured test tubes.

Think of it like this

The college lab journal

Every physics practical follows the same format: aim, apparatus, procedure, observation, result. Any student can open your journal and follow it. Good test scripts have a fixed shape too: set up, do the action, check the result.

Watch it happen

Arrange, Act, Assert

Arrange

Act

Assert

Clean up

1/4Set the scene: create test data, open the page, log in if needed.

The big ideas

What you need to know

Names explain intent

test_coupon_reduces_total_by_10_percent beats test1. The name is the first documentation.

One behaviour per test

A test that checks ten things fails for ten reasons. Keep each test focused.

Read before you edit

Run an existing test first, then trace it top to bottom before changing anything.

Comments say why

The code shows what. Comments explain the business rule or the odd workaround.

See it in code

Walk through the code

python

1def apply_coupon(total, code):2    return total * 0.9 if code == "SAVE10" else total3 4 5def test_save10_coupon_takes_10_percent_off():6    # Arrange7    cart_total = 5008 9    # Act10    new_total = apply_coupon(cart_total, "SAVE10")11 12    # Assert13    assert new_total == 450

1/4The code under test. In real work this would be your app or a page action.

A pytest test in Arrange, Act, Assert shape. Run it with pytest -q after pip install pytest.

Save yourself the pain

Common mistakes

Oops

Copying a teammate's test and changing values without understanding it.

Do this instead

Run it, read it line by line, and explain it out loud before editing.

Oops

Hiding magic numbers like 0.9 with no explanation.

Do this instead

Use a named value or comment: SAVE10 gives 10% off.

Your mission

Rewrite a messy test

~30 min

Quick check

In Arrange, Act, Assert, where does 'click the Apply Coupon button' belong?

Go deeper

1Read an open-source test automation script and explain what it does, line by line.
2Practice modifying an existing script to add a new test case.
3Learn to write scripts with clear naming, since automation code is read far more often than written.