[LoadingButton] Fix padding of loading icon in small button

[PunitSoniME]

• I have followed (at least) the PR section of the contributing guide.

Closes #31109

[mui-bot]

Details of bundle changes

Generated by 🚫 dangerJS against fe667a6

[sjdemartini]

Thanks for tackling this PunitSoniME! Is this change ready to merge? Definitely would appreciate the bug fix being released!

[PunitSoniME]

Thanks for tackling this PunitSoniME! Is this change ready to merge? Definitely would appreciate the bug fix being released!

@sjdemartini Yes it is ready to merge

[PunitSoniME]

@sjdemartini

Can you please merge this PR ?

[sjdemartini]

@PunitSoniME I'm not a maintainer unfortunately, just the person who filed the original bug report. @hbjORbj would you be able to merge this in? Thanks!

[siriwatknp]

It should be this, otherwise <LoadingButton size="small" variant="text"> will cause a regression.

{
  ...(ownerState.loadingPosition === 'start' &&
    (ownerState.variant === 'outlined' || ownerState.variant === 'contained') && {
      left: ownerState.size === 'small' ? 10 : 14,
    }),
 ...(ownerState.loadingPosition === 'end' &&
    (ownerState.variant === 'outlined' || ownerState.variant === 'contained') && {
      right: ownerState.size === 'small' ? 10 : 14,
    }),
}

Also, can you add size small to the loading demo so that we have the regression test.

[hbjORbj]

@sjdemartini Hey, sure, we can merge after tests are written.

@PunitSoniME Would you add unit tests for the change you made? You can add them to this file: https://github.com/mui/material-ui/blob/master/packages/mui-lab/src/LoadingButton/LoadingButton.test.js

[oliviertassinari]

Would you add unit tests for the change you made?

Would a visual test be more effective?

[siriwatknp]

Would you add unit tests for the change you made?

Would a visual test be more effective?

adding a small button to the loading demo should be enough.

[PunitSoniME]

@siriwatknp @oliviertassinari @hbjORbj
Small button demo added for button component

I hope this would be enough to merge.

[siriwatknp]

👍 Thanks for the fix! I updated the demo to have initial loading so that we can track the visual regression.