Скачать или смотреть How to Update the Value of a input type="time" / using @ testing-library/user-event

Learn how to successfully test the user input for a ` input type="time" / ` element in your React applications using `@ testing-library/user-event`, along with common pitfalls and their solutions.
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Introduction

Testing user inputs is a critical aspect of developing robust React applications. Utilizing <input type="time" /> can sometimes lead to unexpected surprises when it comes to testing, especially if you are using @ testing-library/user-event. One common issue developers face is a failing test case when trying to update the time input’s value. If you’ve ever encountered this problem, you’re not alone!

In this guide, we’ll explore the issue, showing why certain tests fail when trying to capture user input for a time input field. Most importantly, we’ll guide you through the solution, ensuring that your tests run smoothly and accurately.

Understanding the Problem

Let’s set the stage with an example. You might have a simple component with a time input like this:

[[See Video to Reveal this Text or Code Snippet]]

Imagine you have written a test to ensure that the user can change the time from its default value of 10:30 to 06:45. However, upon running the test, you might see something like this:

[[See Video to Reveal this Text or Code Snippet]]

This indicates that despite attempting to change the value, the test fails because it does not reflect the expected outcome.

Why Does This Test Fail?

The failure is rooted in how the userEvent.type() function operates. When using this function, it simulates typing into the input field. However, if the input field already has a value, what happens is that the user event does not clear the current value before typing the new one.

In this case, the cursor starts at the current position and types in the new value, leading to unexpected values, such as 10:59.

The Solution

To solve this problem, you can leverage the initialSelectionStart and initialSelectionEnd properties when calling userEvent.type(). These properties allow you to:

Highlight the current text in the input field.

Clear it out before typing the new value completely.

Step-by-Step Implementation

Here’s how you can update your test to make it work correctly:

Set up Your Test: Keep your current test as it is, but add the selection properties.

Use the Selection Properties: Update your userEvent.type() call by including initialSelectionStart and initialSelectionEnd.

Here’s the revised test code:

[[See Video to Reveal this Text or Code Snippet]]

Key Takeaways

Understanding User Events: It’s crucial to know how userEvent simulates typing so that you can manipulate the input values effectively.

Using Selection Properties: Utilizing initialSelectionStart and initialSelectionEnd is key to ensuring previous inputs are cleared and replaced.

By following the solution presented above, you can ensure your tests pass successfully, giving you confidence in your application’s input handling.

Conclusion

Testing user interactions, especially with form elements like <input type="time" />, can initially seem challenging. However, with the right understanding and the proper approach, you can navigate these challenges smoothly. By applying the initialSelectionStart and initialSelectionEnd properties during your typing simulation, you can effectively update input values and ensure your tests reflect the intended behaviors. Happy testing!