57 lines
1.8 KiB
Markdown
57 lines
1.8 KiB
Markdown
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---
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title: >
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Structure a new test by writing comments first
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pubDate: 2023-04-26
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permalink: >-
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archive/2023/04/26/tdd-structure-a-new-test-by-writing-comments-first
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tags:
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- automated-testing
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- test-driven-development
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---
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Test cases are usually split into two or three sections - "Arrange, Act, Assert" or "Given, When, Then".
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If the test has a prerequisite, such as some users or content to be created or in a given state, you create the required environment for the test. With unit tests, this would include mocking any dependencies you need to use.
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Then you perform an action on the subject under test and, finally, assert that the system is in the desired state.
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Maybe a user was pending initially, and they're active after running a command or a cron task. You can assert the initial state of the user as well as the final state to ensure the action did what it was supposed to do.
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## Option 1
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To help me get started, I'll sometimes write a test like this with placeholders to separate the test into its separate stages:
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```php
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/** @test */
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function should_activate_a_pending_user(): void {
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// Arrange.
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// Act.
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// Assert.
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}
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```
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This makes me think about the different stages and what each might need to contain.
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## Option 2
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Or I might write it out in the "Given, When, Then" format:
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```php
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/** @test */
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function should_activate_a_pending_user(): void {
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// Given I have a user.
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// And the user is pending.
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// When I run the user update command.
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// Then the user should no longer be 'pending'.
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// And the user status should be 'active'.
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}
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```
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This takes a little longer to write but feels more familiar if you're used to a behavioural testing framework like Behat.
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Either way, sometimes, I'll remove the comments once I've written the code around them or leave them to provide additional context.
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