feat(form-core): add details.isTriggeredByUser to model-value-changed

packages/form-core/src/FormControlMixin.js

@@ -4,6 +4,16 @@ import { FormRegisteringMixin } from './registration/FormRegisteringMixin.js';
 import { getAriaElementsInRightDomOrder } from './utils/getAriaElementsInRightDomOrder.js';
 import { Unparseable } from './validate/Unparseable.js';
 
+/**
+ * @typedef {import('@lion/core').TemplateResult} TemplateResult
+ * @typedef {import('@lion/core').CSSResult} CSSResult
+ * @typedef {import('@lion/core').nothing} nothing
+ * @typedef {import('@lion/core/types/SlotMixinTypes').SlotsMap} SlotsMap
+ * @typedef {import('../types/FormControlMixinTypes.js').FormControlHost} FormControlHost
+ * @typedef {import('../types/FormControlMixinTypes.js').FormControlMixin} FormControlMixin
+ * @typedef {import('../types/FormControlMixinTypes.js').ModelValueEventDetails} ModelValueEventDetails
+ */
+
 /**
  * Generates random unique identifier (for dom elements)
  * @param {string} prefix
@@ -18,11 +28,6 @@ function uuid(prefix) {
  * This Mixin is a shared fundament for all form components, it's applied on:
  * - LionField (which is extended to LionInput, LionTextarea, LionSelect etc. etc.)
  * - LionFieldset (which is extended to LionRadioGroup, LionCheckboxGroup, LionForm)
- * @typedef {import('@lion/core').TemplateResult} TemplateResult
- * @typedef {import('@lion/core').CSSResult} CSSResult
- * @typedef {import('@lion/core').nothing} nothing
- * @typedef {import('@lion/core/types/SlotMixinTypes').SlotsMap} SlotsMap
- * @typedef {import('../types/FormControlMixinTypes.js').FormControlMixin} FormControlMixin
  * @param {import('@open-wc/dedupe-mixin').Constructor<import('@lion/core').LitElement>} superclass
  * @type {FormControlMixin}
  */
@@ -750,7 +755,11 @@ const FormControlMixinImplementation = superclass =>
       this.dispatchEvent(
         new CustomEvent('model-value-changed', {
           bubbles: true,
-          detail: { formPath: [this], initialize: true },
+          detail: /** @type {ModelValueEventDetails} */ ({
+            formPath: [this],
+            initialize: true,
+            isTriggeredByUser: false,
+          }),
         }),
       );
     }
@@ -822,7 +831,13 @@ const FormControlMixinImplementation = superclass =>
       //
       // Since for a11y everything needs to be in lightdom, we don't add 'composed:true'
       this.dispatchEvent(
-        new CustomEvent('model-value-changed', { bubbles: true, detail: { formPath } }),
+        new CustomEvent('model-value-changed', {
+          bubbles: true,
+          detail: /** @type {ModelValueEventDetails} */ ({
+            formPath,
+            isTriggeredByUser: Boolean(ev.detail?.isTriggeredByUser),
+          }),
+        }),
       );
     }
 

packages/form-core/src/FormatMixin.js

@@ -8,6 +8,7 @@ import { ValidateMixin } from './validate/ValidateMixin.js';
 /**
  * @typedef {import('../types/FormatMixinTypes').FormatMixin} FormatMixin
  * @typedef {import('@lion/localize/types/LocalizeMixinTypes').FormatNumberOptions} FormatOptions
+ * @typedef {import('../types/FormControlMixinTypes.js').ModelValueEventDetails} ModelValueEventDetails
  */
 
 // For a future breaking release:
@@ -316,7 +317,10 @@ const FormatMixinImplementation = superclass =>
       this.dispatchEvent(
         new CustomEvent('model-value-changed', {
           bubbles: true,
-          detail: { formPath: [this] },
+          detail: /** @type { ModelValueEventDetails } */ ({
+            formPath: [this],
+            isTriggeredByUser: Boolean(this.__isHandlingUserInput),
+          }),
         }),
       );
     }

packages/form-core/src/choice-group/ChoiceInputMixin.js

@@ -175,6 +175,7 @@ const ChoiceInputMixinImplementation = superclass =>
         <small class="choice-field__help-text">
           <slot name="help-text"></slot>
         </small>
+        ${this._afterTemplate()}
       `;
     }
 
@@ -182,6 +183,10 @@ const ChoiceInputMixinImplementation = superclass =>
       return nothing;
     }
 
+    _afterTemplate() {
+      return nothing;
+    }
+
     connectedCallback() {
       super.connectedCallback();
       this.addEventListener('user-input-changed', this.__toggleChecked);
@@ -196,7 +201,9 @@ const ChoiceInputMixinImplementation = superclass =>
       if (this.disabled) {
         return;
       }
+      this.__isHandlingUserInput = true;
       this.checked = !this.checked;
+      this.__isHandlingUserInput = false;
     }
 
     /**

packages/form-core/test-suites/FormatMixin.suite.js

@@ -123,18 +123,23 @@ export function runFormatMixinSuite(customConfig) {
       `);
     });
 
-    it('fires `model-value-changed` for every change on the input', async () => {
+    it('fires `model-value-changed` for every input triggered by user', async () => {
       const formatEl = /** @type {FormatClass} */ (await fixture(
         html`<${elem}><input slot="input"></${elem}>`,
       ));
 
       let counter = 0;
-      formatEl.addEventListener('model-value-changed', () => {
+      let isTriggeredByUser = false;
+      formatEl.addEventListener('model-value-changed', (
+        /** @param {CustomEvent} event */ event,
+      ) => {
         counter += 1;
+        isTriggeredByUser = /** @type {CustomEvent} */ (event).detail.isTriggeredByUser;
       });
 
       mimicUserInput(formatEl, generateValueBasedOnType());
       expect(counter).to.equal(1);
+      expect(isTriggeredByUser).to.be.true;
 
       // Counter offset +1 for Date because parseDate created a new Date object
       // when the user changes the value.
@@ -150,17 +155,21 @@ export function runFormatMixinSuite(customConfig) {
       expect(counter).to.equal(2 + counterOffset);
     });
 
-    it('fires `model-value-changed` for every modelValue change', async () => {
+    it('fires `model-value-changed` for every programmatic modelValue change', async () => {
       const el = /** @type {FormatClass} */ (await fixture(
         html`<${elem}><input slot="input"></${elem}>`,
       ));
       let counter = 0;
-      el.addEventListener('model-value-changed', () => {
+      let isTriggeredByUser = false;
+
+      el.addEventListener('model-value-changed', event => {
         counter += 1;
+        isTriggeredByUser = /** @type {CustomEvent} */ (event).detail.isTriggeredByUser;
       });
 
       el.modelValue = 'one';
       expect(counter).to.equal(1);
+      expect(isTriggeredByUser).to.be.false;
 
       // no change means no event
       el.modelValue = 'one';

packages/form-core/test-suites/choice-group/ChoiceInputMixin.suite.js

@@ -95,6 +95,21 @@ export function runChoiceInputMixinSuite({ tagString } = {}) {
       expect(counter).to.equal(1);
     });
 
+    it('adds "isTriggerByUser" flag on model-value-changed', async () => {
+      let isTriggeredByUser;
+      const el = /** @type {ChoiceInput} */ (await fixture(html`
+      <${tag}
+        @model-value-changed="${(/** @type {CustomEvent} */ event) => {
+          isTriggeredByUser = event.detail.isTriggeredByUser;
+        }}"
+      >
+        <input slot="input" />
+      </${tag}>
+    `));
+      el._inputNode.dispatchEvent(new CustomEvent('change', { bubbles: true }));
+      expect(isTriggeredByUser).to.be.true;
+    });
+
     it('can be required', async () => {
       const el = /** @type {ChoiceInput} */ (await fixture(html`
       <${tag} .choiceValue=${'foo'} .validators=${[new Required()]}></${tag}>

packages/form-core/test/FormControlMixin.test.js

@@ -238,14 +238,19 @@ describe('FormControlMixin', () => {
         const fieldsetEv = fieldsetSpy.firstCall.args[0];
         expect(fieldsetEv.target).to.equal(fieldsetEl);
         expect(fieldsetEv.detail.formPath).to.eql([fieldsetEl]);
+        expect(fieldsetEv.detail.initialize).to.be.true;
 
         expect(formSpy.callCount).to.equal(1);
         const formEv = formSpy.firstCall.args[0];
         expect(formEv.target).to.equal(formEl);
         expect(formEv.detail.formPath).to.eql([formEl]);
+        expect(formEv.detail.initialize).to.be.true;
       });
     });
 
+    /**
+     * After initialization means: events triggered programmatically or by user actions
+     */
     describe('After initialization', () => {
       it('redispatches one event from host and keeps formPath history', async () => {
         const formSpy = sinon.spy();
@@ -310,11 +315,45 @@ describe('FormControlMixin', () => {
         const choiceGroupEv = choiceGroupSpy.firstCall.args[0];
         expect(choiceGroupEv.target).to.equal(choiceGroupEl);
         expect(choiceGroupEv.detail.formPath).to.eql([choiceGroupEl]);
+        expect(choiceGroupEv.detail.isTriggeredByUser).to.be.false;
 
         expect(formSpy.callCount).to.equal(1);
         const formEv = formSpy.firstCall.args[0];
         expect(formEv.target).to.equal(formEl);
         expect(formEv.detail.formPath).to.eql([choiceGroupEl, formEl]);
+        expect(formEv.detail.isTriggeredByUser).to.be.false;
+      });
+
+      it('sets "isTriggeredByUser" event detail when event triggered by user', async () => {
+        const formSpy = sinon.spy();
+        const fieldsetSpy = sinon.spy();
+        const fieldSpy = sinon.spy();
+        const formEl = await fixture(html`
+          <${groupTag} name="form">
+            <${groupTag} name="fieldset">
+              <${tag} name="field"></${tag}>
+            </${groupTag}>
+          </${groupTag}>
+        `);
+        const fieldEl = formEl.querySelector('[name=field]');
+        const fieldsetEl = formEl.querySelector('[name=fieldset]');
+
+        formEl.addEventListener('model-value-changed', formSpy);
+        fieldsetEl?.addEventListener('model-value-changed', fieldsetSpy);
+        fieldEl?.addEventListener('model-value-changed', fieldSpy);
+
+        fieldEl?.dispatchEvent(
+          new CustomEvent('model-value-changed', {
+            bubbles: true,
+            detail: { isTriggeredByUser: true },
+          }),
+        );
+
+        const fieldsetEv = fieldsetSpy.firstCall.args[0];
+        expect(fieldsetEv.detail.isTriggeredByUser).to.be.true;
+
+        const formEv = formSpy.firstCall.args[0];
+        expect(formEv.detail.isTriggeredByUser).to.be.true;
       });
     });
   });

packages/form-core/types/FormControlMixinTypes.d.ts

@@ -6,6 +6,29 @@ import { DisabledHost } from '@lion/core/types/DisabledMixinTypes';
 import { LionValidationFeedback } from '../src/validate/LionValidationFeedback';
 import { FormRegisteringHost } from './registration/FormRegisteringMixinTypes';
 
+export type ModelValueEventDetails {
+  /**
+   * A list that represents the path of FormControls the model-value-changed event
+   * 'traveled through'.
+   * (every FormControl stops propagation of its child and sends a new event, hereby adding
+   * itself to the beginning of formPath)
+   */
+  formPath: HTMLElement[];
+  /**
+   * Whether the model-value-changed event is triggered via user interaction. This information
+   * can be helpful for both Application Developers and Subclassers.
+   * This concept is related to the native isTrusted property:
+   * https://developer.mozilla.org/en-US/docs/Web/API/Event/isTrusted
+   */
+  isTriggeredByUser: boolean;
+  /**
+   * Whether it is the first event sent on initialization of the form (other
+   * model-value-changed events are triggered imperatively or via user input (in the latter
+   * case `isTriggeredByUser` is true))
+   */
+  initialize?: boolean;
+}
+
 declare interface HTMLElementWithValue extends HTMLElement {
   value: string;
 }
@@ -40,12 +63,12 @@ export declare class FormControlHost {
    * controls until they are enabled.
    * (From: https://developer.mozilla.org/en-US/docs/Web/HTML/Element/input#attr-readonly)
    */
-  readOnly: boolean;
+  public readOnly: boolean;
   /**
-   * The name the element will be registered on to the .formElements collection
+   * The name the element will be registered with to the .formElements collection
    * of the parent.
    */
-  name: string;
+  public name: string;
   /**
    * The model value is the result of the parser function(when available).
    * It should be considered as the internal value used for validation and reasoning/logic.
@@ -58,25 +81,25 @@ export declare class FormControlHost {
    * - For a number input: a formatted String '1.234,56' will be converted to a Number:
    *   1234.56
    */
-  modelValue: unknown;
+  public modelValue: unknown;
   /**
    * The label text for the input node.
    * When no light dom defined via [slot=label], this value will be used
    */
-  get label(): string;
-  set label(arg: string);
+  public get label(): string;
+  public set label(arg: string);
   __label: string | undefined;
   /**
    * The helpt text for the input node.
    * When no light dom defined via [slot=help-text], this value will be used
    */
-  get helpText(): string;
-  set helpText(arg: string);
+  public get helpText(): string;
+  public set helpText(arg: string);
   __helpText: string | undefined;
-  set fieldName(arg: string);
-  get fieldName(): string;
+  public set fieldName(arg: string);
+  public get fieldName(): string;
   __fieldName: string | undefined;
-  get slots(): SlotsMap;
+  public get slots(): SlotsMap;
   get _inputNode(): HTMLElementWithValue;
   get _labelNode(): HTMLElement;
   get _helpTextNode(): HTMLElement;
@@ -123,7 +146,7 @@ export declare class FormControlHost {
   __reflectAriaAttr(attrName: string, nodes: HTMLElement[], reorder: boolean | undefined): void;
   _isEmpty(modelValue?: unknown): boolean;
   _getAriaDescriptionElements(): HTMLElement[];
-  addToAriaLabelledBy(
+  public addToAriaLabelledBy(
     element: HTMLElement,
     customConfig?: {
       idPrefix?: string | undefined;
@@ -131,7 +154,7 @@ export declare class FormControlHost {
     },
   ): void;
   __reorderAriaLabelledNodes: boolean | undefined;
-  addToAriaDescribedBy(
+  public addToAriaDescribedBy(
     element: HTMLElement,
     customConfig?: {
       idPrefix?: string | undefined;

packages/form-integrations/docs/17-validation-examples.md

@@ -58,11 +58,7 @@ Useful on input elements it allows to define how many characters can be entered.
 
 ```js preview-story
 export const stringValidators = () => html`
-  <lion-input
-    .validators=${[new EqualsLength(7)]}
-    .modelValue=${'not exactly'}
-    label="EqualsLength"
-  ></lion-input>
+  <lion-input .validators=${[new EqualsLength(7)]} label="EqualsLength"></lion-input>
   <lion-input
     .validators=${[new MinLength(10)]}
     .modelValue=${'too short'}

packages/form-integrations/test/model-value-consistency.test.js

@@ -26,6 +26,8 @@ import '@lion/listbox/lion-option.js';
 import '@lion/select-rich/lion-select-rich.js';
 
 import '@lion/fieldset/lion-fieldset.js';
+import '@lion/form/lion-form.js';
+import '@lion/form-core/lion-field.js';
 
 const featureName = 'model value';
 
@@ -278,3 +280,178 @@ describe('lion-fieldset', () => {
     });
   });
 });
+
+describe('detail.isTriggeredByUser', () => {
+  const allFormControls = [
+    // 1) Fields
+    'field',
+    // 1a) Input Fields
+    'input',
+    'input-amount',
+    'input-date',
+    'input-datepicker',
+    'input-email',
+    'input-iban',
+    'input-range',
+    'textarea',
+    // 1b) Choice Fields
+    'option',
+    'checkbox',
+    'radio',
+    // 1c) Choice Group Fields
+    'select',
+    'listbox',
+    'select-rich',
+    'combobox',
+    // 2) FormGroups
+    // 2a) Choice FormGroups
+    'checkbox-group',
+    'radio-group',
+    // 2v) Fieldset
+    'fieldset',
+    // 2c) Form
+    'form',
+  ];
+
+  /**
+   * "isTriggeredByUser" for different types of fields:
+   *
+   * RegularField:
+   * - true: when change/input (c.q. user-input-changed) fired
+   * - false: when .modelValue set programmatically
+   *
+   * ChoiceField:
+   * - true: when 'change' event fired
+   * - false: when .modelValue (or checked) set programmatically
+   *
+   * OptionChoiceField:
+   * - true: when 'click' event fired
+   * - false: when .modelValue (or checked) set programmatically
+   *
+   * ChoiceGroupField (listbox, select-rich, combobox, radio-group, checkbox-group):
+   * - true: when child formElement condition for Choice Field is met
+   * - false: when child formElement condition for Choice Field is not met
+   *
+   * FormOrFieldset (fieldset, form):
+   * - true: when child formElement condition for Field is met
+   * - false: when child formElement condition for Field is not met
+   */
+
+  const featureDetectChoiceField = el => 'checked' in el && 'choiceValue' in el;
+  const featureDetectOptionChoiceField = el => 'active' in el;
+
+  /**
+   * @param {FormControl} el
+   * @returns {'RegularField'|'ChoiceField'|'OptionChoiceField'|'ChoiceGroupField'|'FormOrFieldset'}
+   */
+  function detectType(el) {
+    if (el._repropagationRole === 'child') {
+      if (featureDetectChoiceField(el)) {
+        return featureDetectOptionChoiceField(el) ? 'OptionChoiceField' : 'ChoiceField';
+      }
+      return 'RegularField';
+    }
+    return el._repropagationRole === 'choice-group' ? 'ChoiceGroupField' : 'FormOrFieldset';
+  }
+
+  /**
+   * @param {FormControl} el
+   * @param {string} newViewValue
+   * @returns {'RegularField'|'ChoiceField'|'OptionChoiceField'|'ChoiceGroupField'|'FormOrFieldset'}
+   */
+  function mimicUserInput(el, newViewValue) {
+    const type = detectType(el);
+    let userInputEv;
+    if (type === 'RegularField') {
+      userInputEv = el._inputNode.tagName === 'SELECT' ? 'change' : 'input';
+      el.value = newViewValue; // eslint-disable-line no-param-reassign
+      el._inputNode.dispatchEvent(new Event(userInputEv, { bubbles: true }));
+    } else if (type === 'ChoiceField') {
+      el._inputNode.dispatchEvent(new Event('change', { bubbles: true }));
+    } else if (type === 'OptionChoiceField') {
+      el.dispatchEvent(new Event('click', { bubbles: true }));
+    }
+  }
+
+  allFormControls.forEach(controlName => {
+    it(`lion-${controlName} adds "detail.isTriggeredByUser" to model-value-changed event`, async () => {
+      const spy = sinon.spy();
+
+      const tagname = `lion-${controlName}`;
+      const tag = unsafeStatic(tagname);
+      let childrenEl;
+      if (controlName === 'select') {
+        childrenEl = await fixture(
+          html`<select slot="input">
+            <option value="x"></option>
+          </select>`,
+        );
+      } else if (controlName === 'form') {
+        childrenEl = await fixture(html`<form></form>`);
+      } else if (controlName === 'field') {
+        childrenEl = await fixture(html`<input slot="input" />`);
+      }
+      const el = await fixture(html`<${tag}>${childrenEl}</${tag}>`);
+      await el.registrationComplete;
+      el.addEventListener('model-value-changed', spy);
+
+      function expectCorrectEventMetaRegularField(formControl) {
+        mimicUserInput(formControl, 'userValue', 'RegularField');
+        expect(spy.firstCall.args[0].detail.isTriggeredByUser).to.be.true;
+        // eslint-disable-next-line no-param-reassign
+        formControl.modelValue = 'programmaticValue';
+        expect(spy.secondCall.args[0].detail.isTriggeredByUser).to.be.false;
+      }
+
+      function resetChoiceFieldToForceRepropagation(formControl) {
+        // eslint-disable-next-line no-param-reassign
+        formControl.checked = false;
+        spy.resetHistory();
+      }
+
+      function expectCorrectEventMetaChoiceField(formControl) {
+        resetChoiceFieldToForceRepropagation(formControl);
+        mimicUserInput(formControl, 'userValue', 'ChoiceField');
+        expect(spy.firstCall.args[0].detail.isTriggeredByUser).to.be.true;
+
+        resetChoiceFieldToForceRepropagation(formControl);
+        // eslint-disable-next-line no-param-reassign
+        formControl.checked = true;
+        expect(spy.firstCall.args[0].detail.isTriggeredByUser).to.be.false;
+
+        // eslint-disable-next-line no-param-reassign
+        formControl.modelValue = { value: 'programmaticValue', checked: false };
+        expect(spy.secondCall.args[0].detail.isTriggeredByUser).to.be.false;
+      }
+
+      // 1. Derive the type of field we're dealing with
+      const type = detectType(el);
+      if (type === 'RegularField') {
+        expectCorrectEventMetaRegularField(el);
+      } else if (type === 'ChoiceField' || type === 'OptionChoiceField') {
+        expectCorrectEventMetaChoiceField(el);
+      } else if (type === 'ChoiceGroupField') {
+        let childName = 'option';
+        if (controlName.endsWith('-group')) {
+          [childName] = controlName.split('-group');
+        }
+        const childTagName = `lion-${childName}`;
+        const childTag = unsafeStatic(childTagName);
+        const childrenEls = await fixture(
+          html`<div><${childTag}></${childTag}><${childTag}></${childTag}></div>`,
+        );
+        el.appendChild(childrenEls);
+        await el.registrationComplete;
+        expectCorrectEventMetaChoiceField(el.formElements[0]);
+      } else if (type === 'FormOrFieldset') {
+        const childrenEls = await fixture(
+          html`<div><lion-input name="one"></lion-input><lion-input name="two"></lion-input></div>`,
+        );
+        el.appendChild(childrenEls);
+        await el.registrationComplete;
+        await el.updateComplete;
+        expectCorrectEventMetaRegularField(el.formElements[0]);
+      }
+    });
+  });
+});

packages/listbox/src/LionOption.js

@@ -123,6 +123,7 @@ export class LionOption extends DisabledMixin(ChoiceInputMixin(FormRegisteringMi
       return;
     }
     const parentForm = /** @type {unknown} */ (this.__parentFormGroup);
+    this.__isHandlingUserInput = true;
     if (parentForm && /** @type {ChoiceGroupHost} */ (parentForm).multipleChoice) {
       this.checked = !this.checked;
       this.active = !this.active;
@@ -130,5 +131,6 @@ export class LionOption extends DisabledMixin(ChoiceInputMixin(FormRegisteringMi
       this.checked = true;
       this.active = true;
     }
+    this.__isHandlingUserInput = false;
   }
 }

packages/listbox/src/ListboxMixin.js

@@ -14,6 +14,7 @@ import { LionOptions } from './LionOptions.js';
  * @typedef {import('../types/ListboxMixinTypes').ListboxMixin} ListboxMixin
  * @typedef {import('../types/ListboxMixinTypes').ListboxHost} ListboxHost
  * @typedef {import('@lion/form-core/types/registration/FormRegistrarPortalMixinTypes').FormRegistrarPortalHost} FormRegistrarPortalHost
+ * @typedef {import('@lion/form-core/types/FormControlMixinTypes.js').ModelValueEventDetails} ModelValueEventDetails
  */
 
 function uuid() {
@@ -699,7 +700,13 @@ const ListboxMixinImplementation = superclass =>
       // only send model-value-changed if the event is caused by one of its children
       if (ev.detail && ev.detail.formPath) {
         this.dispatchEvent(
-          new CustomEvent('model-value-changed', { detail: { element: ev.target } }),
+          new CustomEvent('model-value-changed', {
+            detail: /** @type {ModelValueEventDetails} */ ({
+              formPath: ev.detail.formPath,
+              isTriggeredByUser: ev.detail.isTriggeredByUser,
+              element: ev.target,
+            }),
+          }),
         );
       }
       this.__oldModelValue = this.modelValue;

packages/listbox/test/lion-option.test.js

@@ -13,6 +13,38 @@ describe('lion-option', () => {
       expect(el.modelValue).to.deep.equal({ value: 10, checked: false });
     });
 
+    it('fires model-value-changed on click', async () => {
+      let isTriggeredByUser;
+      const el = /** @type {LionOption} */ (await fixture(html`
+        <lion-option
+          @model-value-changed="${(/** @type {CustomEvent} */ event) => {
+            isTriggeredByUser = event.detail.isTriggeredByUser;
+          }}"
+        >
+        </lion-option>
+      `));
+      el.dispatchEvent(new CustomEvent('click', { bubbles: true }));
+      expect(isTriggeredByUser).to.be.true;
+    });
+
+    it('fires model-value-changed on programmatic "checked" change', async () => {
+      let count = 0;
+      let isTriggeredByUser;
+
+      const el = /** @type {LionOption} */ (await fixture(html`
+        <lion-option
+          @model-value-changed="${(/** @type {CustomEvent} */ event) => {
+            count += 1;
+            isTriggeredByUser = event.detail.isTriggeredByUser;
+          }}"
+        >
+        </lion-option>
+      `));
+      el.checked = true;
+      expect(count).to.equal(1);
+      expect(isTriggeredByUser).to.be.false;
+    });
+
     it('can be checked', async () => {
       const el = /** @type {LionOption} */ (await fixture(
         html`<lion-option .choiceValue=${10} checked></lion-option>`,