Test for hidden value workarounds for checkbox inputs so they can sen…

README.md

@@ -850,8 +850,11 @@ of all cases covered:
     unchecked.
   - if there's more than one checkbox with the same `name` attribute, they are
     all treated collectively as a single form control, which returns the value
-    as an **array** containing all the values of the selected checkboxes in the
+    as an **array** containing all the values of the checkboxes in the
     collection.
+  - a hidden input with same name before the checkbox is allowed which is a
+    common workaround to allow browsers to send `false` for unchecked
+    checkboxes.
 - `<input type="radio">` elements are all grouped by the `name` attribute, and
   such a group treated as a single form control. This form control returns the
   value as a **string** corresponding to the `value` attribute of the selected

src/__tests__/to-have-form-values.js

@@ -189,6 +189,21 @@ describe('.toHaveFormValues', () => {
       }).toThrowError(/must be of the same type/)
     })
 
+    it('allows a checkbox and a hidden input which is a common workaround so forms can send "false" for a checkbox', () => {
+      const {container} = render(`
+        <form>
+          <input type="hidden" name="checkbox-with-hidden-false" value=0>
+          <input type="checkbox" name="checkbox-with-hidden-false" value=1>
+        </form>
+      `)
+      const form = container.querySelector('form')
+      expect(() => {
+        expect(form).toHaveFormValues({
+          'checkbox-with-hidden-false': ['0', '1'],
+        })
+      }).not.toThrowError()
+    })
+
     it('detects multiple elements with the same type and name', () => {
       const {container} = render(`
         <form>

src/to-have-form-values.js

@@ -11,9 +11,18 @@ import {
 function getMultiElementValue(elements) {
   const types = [...new Set(elements.map(element => element.type))]
   if (types.length !== 1) {
-    throw new Error(
-      'Multiple form elements with the same name must be of the same type',
-    )
+    if (
+      types.length === 2 &&
+      types[0] === 'hidden' &&
+      types[1] === 'checkbox'
+    ) {
+      // Allow the special case where there's a 'checkbox' input, and a matching 'hidden' input
+      // before it, which works around browser forms so a 'false' value is submitted.
+    } else {
+      throw new Error(
+        'Multiple form elements with the same name must be of the same type',
+      )
+    }
   }
   switch (types[0]) {
     case 'radio': {