Fixed Input Unit Block: Unit jumps to px when set to 0

[Mayank-Tripathi32]

fixes #51616

What?

This PR fixes the issue where the unit in the spacer and dimension controls resets to px when the input value is cleared.

Why?

When removing the value from input fields like spacer height or padding in the dimensions control, the unit automatically resets to px. This behavior causes unexpected results and reduces user control over custom styles. Fixing this improves usability and ensures a consistent editing experience.

How?

The fix was applied in packages/components/src/unit-control/index.tsx, where the unit was being dropped when the input value was cleared. The implementation now ensures that when the value is empty, it defaults to 0 with the current unit preserved, preventing the reset to px.

Testing Instructions

1. Open the WordPress editor (post or page).
2. Add a Spacer block inside a stack.
3. Change its unit to vh.
4. Clear the height value to input a new value.
5. Ensure the unit stays as vh and does not revert to px.

Additional Test:

1. Go to Global Styles settings.
2. Select the Button block.
3. Adjust padding values and clear the input fields.
4. Ensure the unit remains consistent and doesn’t default to px.

Screencast

test-unit-controls.mp4

[github-actions]

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Co-authored-by: Mayank-Tripathi32 <[email protected]>
Co-authored-by: yogeshbhutkar <[email protected]>
Co-authored-by: stokesman <[email protected]>
Co-authored-by: ndiego <[email protected]>
Co-authored-by: hanneslsm <[email protected]>

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[Mayank-Tripathi32]

If the proposed changes seem correct, I can update the failing unit tests in each component to handle value instead of undefined. This adjustment will align the tests with the updated behavior and ensure they pass as expected.

[Mayank-Tripathi32]

If the proposed changes seem correct, I can update the failing unit tests in each component to handle value instead of undefined. This adjustment will align the tests with the updated behavior and ensure they pass as expected.

It seems the test cases expects the default behaviour of "undefined", So I think its better to introduce a prop "shouldPreserveUnit" and conditionally add it for required places.

[yogeshbhutkar]

Works as expected ✨

Screen.Recording.2025-01-20.at.4.54.56.PM.mov

[stokesman]

Works as expected ✨

The screen recording you posted doesn’t show properly testing #51616, which requires the Spacer block to be inside a Row/Stack. The issue wasn’t very clear about that. I missed it too #51616 (comment) when I was trying to reproduce the issue initially.

I'm not doubting this PR fixes the issue. The description includes a screen recording demonstrating an actual test of the issue.

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@Mayank-Tripathi32, Why does fixing this require changes to UnitControl? I ask because the issue is not present in all instances of where the component is used. For one, the Spacer block’s innate height control (when not inside the row/stack) does not have the issue. For other examples try a BoxControl story or BorderBoxControl story. They both have a UnitControl but do not have the issue. To me this indicates that it’s probably not a bug in UnitControl.