feat(range): add classes and expose parts to allow individual styling of dual knobs (#30941)

Issue number: resolves #29862

---------

## What is the current behavior?
Range exposes a single part for both knobs & pins. This makes it impossible to style the knobs/pins differently when dual knobs is enabled.

## What is the new behavior?
- Fixes a bug where the knobs would swap A & B when they cross over each other
- Fixes the focus behavior so that dual knobs act the same as a single knob range when focusing a knob
- Adds the following classes to the host element when `dualKnobs` is enabled:
  - `range-dual-knobs`
  - `range-pressed-a` when the knob with name A is pressed
  - `range-pressed-b` when the knob with name B is pressed
  - `range-pressed-lower` when the lower knob is pressed
  - `range-pressed-upper` when the upper knob is pressed
- Adds parts for the following:
  - `knob-handle-a` — The container for the knob with the static `A` identity when `dualKnobs` is `true`. This identity does not change, even if the knobs cross and swap which one represents the lower or upper value.
  - `knob-handle-b` — The container for the knob with the static `B` identity when `dualKnobs` is `true`. This identity does not change, even if the knobs cross and swap which one represents the lower or upper value.
  - `knob-handle-lower` — The container for the knob whose current `value` is `lower` when `dualKnobs` is `true`. The lower and upper parts swap which knob handle they refer to when the knobs cross.
  - `knob-handle-upper` — The container for the knob whose current `value` is `upper` when `dualKnobs` is `true`. The lower and upper parts swap which knob handle they refer to when the knobs cross.
  - `pin-a` — The value indicator above the knob with the static `A` identity when `dualKnobs` is `true`. This identity does not change, even if the knobs cross and swap which one represents the lower or upper value.
  - `pin-b` — The value indicator above the knob with the static `B` identity when `dualKnobs` is `true`. This identity does not change, even if the knobs cross and swap which one represents the lower or upper value.
  - `pin-lower` — The value indicator above the knob whose current `value` is `lower` when `dualKnobs` is `true`. The lower and upper parts swap which pin they refer to when the knobs cross.
  - `pin-upper` — The value indicator above the knob whose current `value` is `upper` when `dualKnobs` is `true`. The lower and upper parts swap which pin they refer to when the knobs cross.
  - `knob-a` — The visual knob for the static `A` identity when `dualKnobs` is `true`. This identity does not change, even if the knobs cross and swap which one represents the lower or upper value.
  - `knob-b` — The visual knob for the static `B` identity when `dualKnobs` is `true`. This identity does not change, even if the knobs cross and swap which one represents the lower or upper value.
  - `knob-lower` — The visual knob whose current `value` is `lower` when `dualKnobs` is `true`. The lower and upper parts swap which knob they refer to when the knobs cross.
  - `knob-upper` — The visual knob whose current `value` is `upper` when `dualKnobs` is `true`. The lower and upper parts swap which knob they refer to when the knobs cross.
  - `activated` — Added to the knob-handle, knob, and pin when the knob is active. Only one set has this part at a time when `dualKnobs` is `true`.
  - `focused` — Added to the knob-handle, knob, and pin that currently has focus. Only one set has this part at a time when `dualKnobs` is `true`.
  - `hover` — Added to the knob-handle, knob, and pin when the knob has hover. Only one set has this part at a time when `dualKnobs` is `true`.
  - `pressed` — Added to the knob-handle, knob, and pin that is currently being pressed to drag. Only one set has this part at a time when `dualKnobs` is `true`.
- Adds e2e tests for the following:
  - customizing label part
  - customizing bar parts
  - customizing pin parts
  - customizing tick parts
  - customizing knob parts
  - customizing dual knob a & b parts
  - customizing dual knob lower & upper parts
- verifies that a & b parts stay on the original elements but lower & upper parts swap when the values swap
- Adds spec tests for the following:
  - css classes
    - value state classes
    - boolean property classes
    - pressed state classes
  - shadow parts
    - static shadow parts
- verifies the shadow parts exist based on the existence of certain range properties
  - state shadow parts
- verifies the shadow parts exist based on the state of the range knob (pressed, focused, activated, hover)

## Does this introduce a breaking change?
- [ ] Yes
- [x] No

---------

Co-authored-by: Brandy Smith <6577830+brandyscarney@users.noreply.github.com>

Author: brandyscarney

core/api.txt

@@ -1488,11 +1488,28 @@ ion-range,css-prop,--pin-background,ios
 ion-range,css-prop,--pin-background,md
 ion-range,css-prop,--pin-color,ios
 ion-range,css-prop,--pin-color,md
+ion-range,part,activated
 ion-range,part,bar
 ion-range,part,bar-active
+ion-range,part,focused
+ion-range,part,hover
 ion-range,part,knob
+ion-range,part,knob-a
+ion-range,part,knob-b
+ion-range,part,knob-handle
+ion-range,part,knob-handle-a
+ion-range,part,knob-handle-b
+ion-range,part,knob-handle-lower
+ion-range,part,knob-handle-upper
+ion-range,part,knob-lower
+ion-range,part,knob-upper
 ion-range,part,label
 ion-range,part,pin
+ion-range,part,pin-a
+ion-range,part,pin-b
+ion-range,part,pin-lower
+ion-range,part,pin-upper
+ion-range,part,pressed
 ion-range,part,tick
 ion-range,part,tick-active
 

core/setupJest.js

@@ -8,7 +8,9 @@ expect.extend({
       throw new Error('expected toHaveShadowPart to be called on an element with a shadow root');
     }
 
-    const shadowPart = received.shadowRoot.querySelector(`[part="${part}"]`);
+    // Use attribute selector with ~= to match space-separated part values
+    // e.g., [part~="knob"] matches elements with part="knob" or part="knob knob-a"
+    const shadowPart = received.shadowRoot.querySelector(`[part~="${part}"]`);
     const pass = shadowPart !== null;
 
     const message = `expected ${received.tagName.toLowerCase()} to have shadow part "${part}"`;

core/src/components/range/range-interface.ts

@@ -1,5 +1,7 @@
 export type KnobName = 'A' | 'B' | undefined;
 
+export type KnobPosition = 'lower' | 'upper' | undefined;
+
 export type RangeValue = number | { lower: number; upper: number };
 
 export type PinFormatter = (value: number) => number | string;