End-to-end Testing with Cypress Series: 06 DRY (Don't Repeat Yourself)

In this video, learn about the DRY (Don’t Repeat Yourself) principle and how it can affect end-to-end tests. After watching this video, you will be able to create reusable helpers for data setup in your own Cypress end-to-end tests.

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(upbeat music)

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Welcome back

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to Test Double's intro course

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on end-to-end testing with Cypress.

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In the previous video,

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you added another real world happy path test,

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learning about other useful commands in Cypress,

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and why not to share persisted state between tests.

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In this video,

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you will learn about the DRY principle,

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learn how duplication can affect tests,

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and reduce some duplication

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in the existing yams test suite.

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DRY is a common acronym used in software development.

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It stands for, "Don't Repeat Yourself."

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The basic premise behind it

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is to make code more maintainable

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by reducing duplicated code and concepts.

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When you need to make a change

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to a piece of duplicated code,

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you have to update that code

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in all the places it's replicated.

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That takes more time

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and can lead to unintended bugs

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if you miss updating a place.

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So developers use various techniques

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to manage code needed in multiple places

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with abstractions that reduce duplication

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and are more maintainable.

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Whether it's duplicated setup code

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or redundant tests,

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duplication poses problems in tests as well,

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making test code harder

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to maintain and understand

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as well as slowing down test suites.

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To see what I mean,

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let's fix one glaring example of duplication

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in the current yams test suite.

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Boot up the back-end server Cypress environment,

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front-end dev server, and Cypress itself.

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Also, ensure you're running

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the tasks.spec.js file in Cypress.

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Inside the spec file,

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you have three spots

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where you duplicate the same code

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to generate a unique task title

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by appending a timestamp.

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Let's extract that logic

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into a reusable function

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so you don't have to repeat it everywhere.

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At the top of the test file above describe,

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add a helper function called uniqueTitle.

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The function accepts the title as an argument

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and returns a version of the title

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with the current timestamp appended.

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Update the spots

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where you manually add the timestamp

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to use this function,

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and then save the file

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to make sure the tests still pass.

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Now, if you ever wanna update the core logic

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of generating a unique title,

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you'll only need to make that change in one place.

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Let's recap what you learned in this video.

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You learned about the DRY principle,

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you learned how duplication affects tests,

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and you reduced some duplication

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in the existing yams test suite

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by creating a reusable function

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to generate unique tasks titles for tests.

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You are now ready to DRY up your own tests,

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but let's take your knowledge further.

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In the next video,

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you will learn how redundant tests

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can violate the DRY principle

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and slow down test suites.

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You will discover how to combine tests

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to reduce duplication and speed up tests.

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(upbeat music)

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‹ End-to-end testing with Cypress series: 05 Isolate test state

End-to-end testing with Cypress series: 07 DRY for speed ›