RangeControl: disable reset button consistently

packages/components/CHANGELOG.md

@@ -59,6 +59,7 @@
 
 ### Bug Fixes
 
+-   `RangeControl`: disable reset button when the current value is equal to the reset value ([#64579](https://github.com/WordPress/gutenberg/pull/64579)).
 -   `RangeControl`: tweak mark and label absolute positioning ([#64487](https://github.com/WordPress/gutenberg/pull/64487)).
 
 ### Internal

packages/components/src/range-control/index.tsx

@@ -41,6 +41,25 @@ import { space } from '../utils/space';
 
 const noop = () => {};
 
+/**
+ * Computes the value that `RangeControl` should reset to when pressing
+ * the reset button.
+ */
+function computeResetValue( {
+	resetFallbackValue,
+	initialPosition,
+}: Pick< RangeControlProps, 'resetFallbackValue' | 'initialPosition' > ) {
+	if ( resetFallbackValue !== undefined ) {
+		return ! Number.isNaN( resetFallbackValue ) ? resetFallbackValue : null;
+	}
+
+	if ( initialPosition !== undefined ) {
+		return ! Number.isNaN( initialPosition ) ? initialPosition : null;
+	}
+
+	return null;
+}
+
 function UnforwardedRangeControl(
 	props: WordPressComponentProps< RangeControlProps, 'input', false >,
 	forwardedRef: ForwardedRef< HTMLInputElement >
@@ -166,13 +185,12 @@ function UnforwardedRangeControl(
 	};
 
 	const handleOnReset = () => {
-		let resetValue: number | null = parseFloat( `${ resetFallbackValue }` );
-		let onChangeResetValue: number | undefined = resetValue;
-
-		if ( isNaN( resetValue ) ) {
-			resetValue = null;
-			onChangeResetValue = undefined;
-		}
+		// Reset to `resetFallbackValue` if defined, otherwise set internal value
+		// to `null` — which, if propagated to the `value` prop, will cause
+		// the value to be reset to the `initialPosition` prop if defined.
+		const resetValue = Number.isNaN( resetFallbackValue )
+			? null
+			: resetFallbackValue ?? null;
 
 		setValue( resetValue );
 
@@ -189,7 +207,7 @@ function UnforwardedRangeControl(
 		 * preserve the undefined callback argument, except when a
 		 * resetFallbackValue is defined.
 		 */
-		onChange( onChangeResetValue );
+		onChange( resetValue ?? undefined );
 	};
 
 	const handleShowTooltip = () => setShowTooltip( true );
@@ -210,6 +228,7 @@ function UnforwardedRangeControl(
 	const offsetStyle = {
 		[ isRTL() ? 'right' : 'left' ]: fillValueOffset,
 	};
+
 	return (
 		<BaseControl
 			__nextHasNoMarginBottom={ __nextHasNoMarginBottom }
@@ -329,7 +348,17 @@ function UnforwardedRangeControl(
 							className="components-range-control__reset"
 							// If the RangeControl itself is disabled, the reset button shouldn't be in the tab sequence.
 							accessibleWhenDisabled={ ! disabled }
-							disabled={ disabled || value === undefined }
+							// The reset button should be disabled if RangeControl itself is disabled,
+							// or if the current `value` is equal to the value that would be currently
+							// assigned when clicking the button.
+							disabled={
+								disabled ||
+								value ===
+									computeResetValue( {
+										resetFallbackValue,
+										initialPosition,
+									} )
+							}
 							variant="secondary"
 							size="small"
 							onClick={ handleOnReset }

packages/components/src/range-control/test/index.tsx

@@ -298,36 +298,67 @@ describe( 'RangeControl', () => {
 	} );
 
 	describe( 'reset', () => {
-		it( 'should reset to a custom fallback value, defined by a parent component', () => {
+		it( 'should clear the input value when clicking the reset button', () => {
+			const spy = jest.fn();
+			render( <RangeControl allowReset onChange={ spy } /> );
+
+			const resetButton = getResetButton();
+			const rangeInput = getRangeInput();
+			const numberInput = getNumberInput();
+
+			fireChangeEvent( numberInput, '14' );
+
+			expect( rangeInput.value ).toBe( '14' );
+			expect( numberInput.value ).toBe( '14' );
+			expect( spy ).toHaveBeenCalledWith( 14 );
+
+			fireEvent.click( resetButton );
+
+			// range input resets to min + (max-min)/2
+			expect( rangeInput.value ).toBe( '50' );
+			expect( numberInput.value ).toBe( '' );
+			expect( spy ).toHaveBeenCalledWith( undefined );
+
+			expect( resetButton ).toHaveAttribute( 'aria-disabled', 'true' );
+		} );
+
+		it( 'should reset to the `initialPosition` value when clicking the reset button', () => {
 			const spy = jest.fn();
 			render(
 				<RangeControl
-					initialPosition={ 10 }
 					allowReset
+					initialPosition={ 23 }
 					onChange={ spy }
-					resetFallbackValue={ 33 }
 				/>
 			);
 
 			const resetButton = getResetButton();
 			const rangeInput = getRangeInput();
 			const numberInput = getNumberInput();
 
+			fireChangeEvent( numberInput, '14' );
+
+			expect( rangeInput.value ).toBe( '14' );
+			expect( numberInput.value ).toBe( '14' );
+			expect( spy ).toHaveBeenCalledWith( 14 );
+
 			fireEvent.click( resetButton );
 
-			expect( rangeInput.value ).toBe( '33' );
-			expect( numberInput.value ).toBe( '33' );
-			expect( spy ).toHaveBeenCalledWith( 33 );
+			expect( rangeInput.value ).toBe( '23' );
+			expect( numberInput.value ).toBe( '23' );
+			expect( spy ).toHaveBeenCalledWith( undefined );
+
+			expect( resetButton ).toHaveAttribute( 'aria-disabled', 'true' );
 		} );
 
-		it( 'should reset to a 50% of min/max value, of no initialPosition or value is defined', () => {
+		it( 'should reset to the `resetFallbackValue` value when clicking the reset button', () => {
+			const spy = jest.fn();
 			render(
 				<RangeControl
-					initialPosition={ undefined }
-					min={ 0 }
-					max={ 100 }
+					initialPosition={ 10 }
 					allowReset
-					resetFallbackValue={ undefined }
+					onChange={ spy }
+					resetFallbackValue={ 33 }
 				/>
 			);
 
@@ -337,8 +368,11 @@ describe( 'RangeControl', () => {
 
 			fireEvent.click( resetButton );
 
-			expect( rangeInput.value ).toBe( '50' );
-			expect( numberInput.value ).toBe( '' );
+			expect( rangeInput.value ).toBe( '33' );
+			expect( numberInput.value ).toBe( '33' );
+			expect( spy ).toHaveBeenCalledWith( 33 );
+
+			expect( resetButton ).toHaveAttribute( 'aria-disabled', 'true' );
 		} );
 	} );
 } );