# Testing (/syntax/testing)



Overview [#overview]

Write comprehensive UI tests using XML to verify functionality and visual consistency of your LVGL interfaces.

The XML test module is a powerful and flexible way to define functional UI tests.

Test XML files are similar to components but are wrapped in a `<test>`
tag and consist of two main parts:

* **UI Definition**: Use [`<styles>`](./styles), [`<consts>`](./constants), and [`<view>`](./view) to define
  how the UI should look. This is identical to how [`<component>`](./components)s are
  structured.
* **Test Steps**: Encapsulated in a `<steps>` tag, these define the
  actions and assertions for the test.

Step Types [#step-types]

The following step types are currently supported:

| Step                                               | Parameters         | Description                                                                                                                                                                 |
| -------------------------------------------------- | ------------------ | --------------------------------------------------------------------------------------------------------------------------------------------------------------------------- |
| `<move_to x="10" y="30"/>`                         | `x`, `y`           | Move the mouse to the specified screen coordinates                                                                                                                          |
| `<click_at x="10" y="30"/>`                        | `x`, `y`           | Simulates a click at the specified screen coordinates                                                                                                                       |
| `<press/>`                                         | —                  | Press on the current screen coordinate                                                                                                                                      |
| `<release/>`                                       | —                  | Release on the current screen coordinate                                                                                                                                    |
| `<wait ms="100"/>`                                 | `ms`               | Waits for the given number of milliseconds. LVGL continues running, including animations and timers                                                                         |
| `<freeze ms="100"/>`                               | `ms`               | Pauses the UI and LVGL's internal time. Useful for visual debugging                                                                                                         |
| `<subject_set subject="subject1" value="5"/>`      | `subject`, `value` | Set an integer or string subject's value                                                                                                                                    |
| `<subject_compare subject="subject1" value="10"/>` | `subject`, `value` | Compare an integer or string subject's value against a reference value                                                                                                      |
| `<screenshot_compare path="path/to/image.png"/>`   | `path`             | Compares the current screen with a reference image. If the image doesn't exist, it is created. If the comparison fails, an image with `_err` suffix is saved for inspection |

Example:

```xml title="xml" lineNumbers=1
<test width="300" height="400">
 <view width="100%" height="100%" flex_flow="column">
 <lv_checkbox text="First one!"/>
 <lv_slider />
 </view>

 <steps>
   <screenshot_compare path="imgs/before.png"/>
   <click_at x="32" y="32"/>
   <subject_compare subject="subject2" value="50"/>
   <click_at x="50" y="64"/>
   <subject_set subject="subject2" value="10"/>
   <wait ms="300"/>
   <screenshot_compare path="imgs/after.png"/>
 </steps>
</test>
```

Running Tests [#running-tests]

Use the "Test" panel of the Editor to see and run tests, or run them with the CLI in a CI/CD pipeline.