fix: set has-value attribute on radio-button click

[vursen]

Description

The PR fixes the radio-group regression that occurred after the a11y refactoring that has been done in #2641:

The radio-group doesn't set the has-value attribute on child radio-button click. The attribute is only set on the next click on another radio-button.

Fixes #2857

Type of change

• Bugfix

Checklist

• I have read the contribution guide: https://vaadin.com/docs-beta/latest/guide/contributing/overview/
• I have added a description following the guideline.
• The issue is created in the corresponding repository and I have referenced it.
• I have added tests to ensure my change is effective and works as intended.
• New and existing tests are passing locally with my change.
• I have performed self-review and corrected misspellings.

[sonarqubecloud]

Kudos, SonarCloud Quality Gate passed!   

0 Bugs
0 Vulnerabilities
0 Security Hotspots
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No Coverage information
0.0% Duplication

[vursen]

The check above doesn't make much sense and it is exactly what causes the regression:

1. Consideration

When the user selects a radio-button, the __valueObserver callback is invoked before the previously selected radio-button gets unchecked:

web-components/packages/radio-group/src/vaadin-radio-group.js

Lines 451 to 460 in bb41c56

	__selectRadioButton(radioButton) {
	if (radioButton) {
	this.value = radioButton.value;
	} else {
	this.value = '';
	}
	this.__radioButtons.forEach((button) => {
	button.checked = button === radioButton;
	});

...so it might happen that the __selectedRadioButton getter returns the previously selected radio-button instead of a new one that results in the has-value attribute inconsistency.

2. Consideration

However, even if the __valueObserver were invoked after the previously selected radio-button was unchecked, the check above wouldn't be correct: the has-value attribute would be set only when changing the value attribute but not when selecting a radio-button. Note, __selectedRadioButton would be always equal to the most recently selected radio-button = that has been just selected.

[vaadin-bot]

This ticket/PR has been released with platform 22.0.0.alpha8 and is also targeting the upcoming stable 22.0.0 version.