fix: check for inherited :disabled (#872)

src/utils/misc/isDisabled.ts

@@ -1,5 +1,37 @@
-// This should probably be extended with checking the element type
-// https://developer.mozilla.org/en-US/docs/Web/HTML/Attributes/disabled
+import {isElementType} from './isElementType'
+
+// This should probably just rely on the :disabled pseudo-class, but JSDOM doesn't implement it properly.
 export function isDisabled(element: Element | null): boolean {
-  return Boolean(element && (element as {disabled?: boolean}).disabled)
+  for (let el = element; el; el = el.parentElement) {
+    if (
+      isElementType(el, [
+        'button',
+        'input',
+        'select',
+        'textarea',
+        'optgroup',
+        'option',
+      ])
+    ) {
+      if (el.hasAttribute('disabled')) {
+        return true
+      }
+    } else if (isElementType(el, 'fieldset')) {
+      if (
+        el.hasAttribute('disabled') &&
+        !el.querySelector(':scope > legend')?.contains(element)
+      ) {
+        return true
+      }
+    } else if (el.tagName.includes('-')) {
+      if (
+        (el.constructor as {formAssociated?: boolean}).formAssociated &&
+        el.hasAttribute('disabled')
+      ) {
+        return true
+      }
+    }
+  }
+
+  return false
 }

tests/utils/misc/isDisabled.ts

@@ -0,0 +1,73 @@
+import cases from 'jest-in-case'
+import {isDisabled} from '#src/utils'
+import {render} from '#testHelpers'
+
+customElements.define(
+  'form-associated',
+  class FormAssociated extends HTMLElement {
+    static formAssociated = true
+    get disabled() {
+      return this.hasAttribute('disabled')
+    }
+  },
+)
+
+customElements.define(
+  'custom-el',
+  class CustomEl extends HTMLElement {
+    get disabled() {
+      return this.hasAttribute('disabled')
+    }
+  },
+)
+
+// https://html.spec.whatwg.org/multipage/semantics-other.html#disabled-elements
+// https://html.spec.whatwg.org/multipage/form-control-infrastructure.html#enabling-and-disabling-form-controls:-the-disabled-attribute
+cases(
+  'check if element is disabled',
+  ({html, node = '//input', expected = true}) => {
+    const {xpathNode} = render(html)
+    expect(isDisabled(xpathNode<Element>(node))).toBe(expected)
+  },
+  {
+    control: {
+      html: `<input/>`,
+      expected: false,
+    },
+    'disabled control': {
+      html: `<input disabled/>`,
+    },
+    'control in disabled fieldset': {
+      html: `<fieldset disabled><input/></fieldset>`,
+    },
+    'control in first legend of disabled fieldset': {
+      html: `<fieldset disabled><legend><input/></legend></fieldset>`,
+      expected: false,
+    },
+    'control in other legend of disabled fieldset': {
+      html: `<fieldset disabled><legend></legend><legend><input/></legend></fieldset>`,
+    },
+    'control in nested legend of disabled fieldset': {
+      html: `<fieldset disabled><div>><legend><input/></legend></div></fieldset>`,
+    },
+    'element without support for disabled': {
+      html: `<div disabled></div>`,
+      node: '*',
+      expected: false,
+    },
+    'form-associated disabled custom element': {
+      html: `<form-associated disabled></form-associated>`,
+      node: '*',
+    },
+    'form-associated enabled custom element': {
+      html: `<form-associated></form-associated>`,
+      node: '*',
+      expected: false,
+    },
+    'other custom element': {
+      html: `<custom-el disabled></custom-el>`,
+      node: '*',
+      expected: false,
+    },
+  },
+)