diff --git a/tests/javascripts/collapsibleCheckboxes.test.js b/tests/javascripts/collapsibleCheckboxes.test.js
new file mode 100644
index 000000000..6a8e266fe
--- /dev/null
+++ b/tests/javascripts/collapsibleCheckboxes.test.js
@@ -0,0 +1,443 @@
+const helpers = require('./support/helpers');
+
+beforeAll(() => {
+  // set up jQuery
+  window.jQuery = require('jquery');
+  $ = window.jQuery;
+
+  // load module code
+  require('govuk_frontend_toolkit/javascripts/govuk/modules.js');
+  require('../../app/assets/javascripts/collapsibleCheckboxes.js');
+});
+
+afterAll(() => {
+  window.jQuery = null;
+  $ = null;
+
+  delete window.GOVUK;
+});
+
+
+describe('Collapsible fieldset', () => {
+
+  let fieldset;
+  let checkboxes;
+
+  beforeEach(() => {
+    const _checkboxes = (start, end, descendents) => {
+      result = '';
+
+        for (let num = start; num <= end; num++) {
+          let id = `folder-permissions-${num}`;
+
+          if (!descendents) { descendents = ''; }
+
+          result += `<li class="multiple-choice">
+            <input id="${id}" name="folder_permissions" type="checkbox" value="${id}">
+            <label class="block-label" for="{id}">
+              Folder 18
+            </label>
+            ${descendents}
+          </li>`;
+        }
+
+        return result;
+    };
+
+    // set up DOM
+    document.body.innerHTML =
+      `<div class="form-group" data-module="collapsible-checkboxes" data-field-label="folder">
+        <fieldset id="folder_permissions">
+          <legend class="form-label heading-small">
+            Folders this team member can see
+          </legend>
+          <div class="checkboxes-nested">
+            <ul>
+              ${_checkboxes(1, 10)}
+            </ul>
+          </div>
+        </fieldset>
+      </div>`;
+
+      formGroup = document.querySelector('.form-group');
+      fieldset = formGroup.querySelector('fieldset');
+      checkboxesContainer = fieldset.querySelector('.checkboxes-nested');
+      checkboxes = checkboxesContainer.querySelectorAll('input[type=checkbox]');
+
+  });
+
+  afterEach(() => {
+
+    document.body.innerHTML = '';
+
+  });
+
+  describe('when started', () => {
+
+    beforeEach(() => {
+
+      // start module
+      window.GOVUK.modules.start();
+
+    });
+
+    afterEach(() => {
+
+      // reset checkboxes to default state
+      checkboxes.forEach(el => el.removeAttribute('checked'));
+
+    });
+
+    test("adds a heading before the selected fieldset", () => {
+
+      const heading = helpers.element(fieldset).getPreviousSibling(
+        el => (el.nodeName === 'h2') && (el.hasClass('heading-small'))
+      );
+
+      expect(heading).not.toBeNull();
+
+    });
+
+    test("has a summary added before the selected fieldset", () => {
+
+      const summary = helpers.element(fieldset).getPreviousSibling(
+        el => (el.nodeName === 'p') && (el.hasClass('selection-summary'))
+      );
+
+      expect(summary).not.toBeNull();
+
+    });
+
+    test("the legend of the fieldset is visually hidden", () => {
+
+      const legend = helpers.element(fieldset.querySelector('legend'));
+
+      expect(legend.hasClass('visuallyhidden')).toBe(true);
+
+    });
+
+    test("has a change button", () => {
+
+      const changeButton = document.querySelector('.selection-summary .button');
+
+      expect(changeButton).not.toBeNull();
+      expect(changeButton.textContent).toEqual('Change Folders this team member can see');
+
+    });
+
+    test("has a 'Done' button", () => {
+
+      const nextEl = fieldset.querySelector('.button');
+
+      expect(helpers.element(nextEl).nodeName).toEqual('button');
+
+    });
+
+    test("has the correct aria attributes on both buttons", () => {
+
+      const changeButton = document.querySelector('.selection-summary .button');
+      const doneButton = fieldset.querySelector('.button');
+
+      // check change button
+      expect(helpers.element(changeButton).hasAttributesSetTo({
+        'aria-controls': fieldset.getAttribute('id'),
+        'aria-expanded': 'false'
+      })).toBe(true);
+
+      // check done button
+      expect(helpers.element(doneButton).hasAttributesSetTo({
+        'aria-controls': fieldset.getAttribute('id'),
+        'aria-expanded': 'false'
+      })).toBe(true);
+
+    });
+
+    test("hides the checkboxes", () => {
+
+      expect(helpers.element(fieldset).is('hidden')).toEqual(true);
+
+    });
+
+  });
+
+  test('has the right summary text when started with no checkboxes selected', () => {
+
+    // start module
+    window.GOVUK.modules.start();
+
+    const summaryText = document.querySelector('.selection-summary__text');
+
+    // default state is for none to be selected
+    expect(summaryText.textContent).toEqual("No folders (only templates outside a folder)");
+
+  });
+
+  test('has the right summary text when started with some checkboxes selected', () => {
+
+    // select the first 3 checkboxes
+    checkboxes.forEach((el, idx) => {
+      if ([0,1,2].includes(idx)) { el.setAttribute('checked', ''); }
+    });
+
+    // start module
+    window.GOVUK.modules.start();
+
+    const summaryText = document.querySelector('.selection-summary__text');
+
+    expect(summaryText.textContent).toEqual("3 of 10 folders");
+
+  });
+
+  test('has the right summary text when started with all checkboxes selected', () => {
+
+    // select all the checkboxes
+    checkboxes.forEach(el => el.setAttribute('checked', ''));
+
+    // start module
+    window.GOVUK.modules.start();
+
+    const summaryText = document.querySelector('.selection-summary__text');
+
+    expect(summaryText.textContent).toEqual("All folders");
+
+  });
+
+  describe("when 'change' is clicked", () => {
+
+    let changeButton;
+    let doneButton;
+
+    beforeEach(() => {
+
+      // start module
+      window.GOVUK.modules.start();
+
+      doneButton = fieldset.querySelector('.button');
+      changeButton = document.querySelector('.selection-summary .button');
+
+      helpers.triggerEvent(changeButton, 'click');
+
+    });
+
+    test("it shows the checkboxes", () => {
+
+      expect(helpers.element(fieldset).is('hidden')).toBe(false);
+
+    });
+    test("it focuses the fieldset", () => {
+
+      expect(document.activeElement).toBe(fieldset);
+
+    });
+    test("it uses ARIA to mark the checkboxes as expanded", () => {
+
+      expect(changeButton.getAttribute('aria-expanded')).toEqual('true');
+      expect(doneButton.getAttribute('aria-expanded')).toEqual('true');
+
+    });
+  });
+
+  describe("when 'done' is clicked", () => {
+
+    let changeButton;
+    let doneButton;
+
+    beforeEach(() => {
+
+      // start module
+      window.GOVUK.modules.start();
+
+      doneButton = fieldset.querySelector('.button');
+      changeButton = document.querySelector('.selection-summary .button');
+
+      // show the checkboxes
+      helpers.triggerEvent(changeButton, 'click');
+
+      // click the done button
+      helpers.triggerEvent(doneButton, 'click');
+
+    });
+
+    test("it hides the checkboxes", () => {
+
+      expect(helpers.element(fieldset).is('hidden')).toBe(true);
+
+    });
+
+    test("it focuses the summary text", () => {
+
+      expect(document.activeElement).toBe(document.querySelector('.selection-summary__text'));
+
+    });
+
+    test("it uses ARIA to mark the checkboxes as collapsed", () => {
+
+      expect(changeButton.getAttribute('aria-expanded')).toEqual('false');
+      expect(doneButton.getAttribute('aria-expanded')).toEqual('false');
+
+    });
+  });
+
+  describe("when the selection changes", () => {
+
+    const showCheckboxes = () => {
+      changeButton = document.querySelector('.selection-summary .button');
+      helpers.triggerEvent(changeButton, 'click');
+    };
+
+    const checkFirstCheckbox = () => {
+      checkboxes[0].setAttribute('checked', '');
+      checkboxes[0].checked = true;
+    };
+
+    const checkAllCheckboxes = () => {
+      Array.from(checkboxes).forEach(checkbox => {
+        checkbox.setAttribute('checked', '');
+        checkbox.checked = true;
+      });
+    };
+
+    const checkAllCheckboxesButTheLast = () => {
+      Array.from(checkboxes).forEach((checkbox, idx) => {
+        if (idx > 0) {
+          checkbox.setAttribute('checked', '');
+          checkbox.checked = true;
+        }
+      });
+    };
+
+    let changeButton;
+
+    describe("from some to none the summary updates to reflect that", () => {
+
+      test("if fields are called 'folders'", () => {
+
+        formGroup.dataset.fieldLabel = 'folder';
+
+        checkFirstCheckbox();
+
+        // start module
+        window.GOVUK.modules.start();
+
+        showCheckboxes();
+
+        const summaryText = document.querySelector('.selection-summary__text');
+
+        // click the first checkbox
+        helpers.triggerEvent(checkboxes[0], 'click');
+
+        expect(summaryText.textContent).toEqual("No folders (only templates outside a folder)");
+
+      });
+
+      test("if fields are called 'team member'", () => {
+
+        formGroup.dataset.fieldLabel = 'team member';
+
+        checkFirstCheckbox();
+
+        // start module
+        window.GOVUK.modules.start();
+
+        showCheckboxes();
+
+        const summaryText = document.querySelector('.selection-summary__text');
+
+        // click the first checkbox
+        helpers.triggerEvent(checkboxes[0], 'click');
+
+        expect(summaryText.textContent).toEqual("No team members");
+
+      });
+
+    });
+
+    describe("from all to some the summary updates to reflect that", () => {
+
+      test("if fields are called 'folder'", () => {
+
+        formGroup.dataset.fieldLabel = 'folder';
+
+        checkAllCheckboxes();
+
+        // start module
+        window.GOVUK.modules.start();
+
+        showCheckboxes();
+
+        const summaryText = document.querySelector('.selection-summary__text');
+
+        // click the first checkbox
+        helpers.triggerEvent(checkboxes[1], 'click');
+
+        expect(summaryText.textContent).toEqual("9 of 10 folders");
+
+      });
+
+      test("if fields are called 'team member'", () => {
+
+        formGroup.dataset.fieldLabel = 'team member';
+
+        checkAllCheckboxes();
+
+        // start module
+        window.GOVUK.modules.start();
+
+        showCheckboxes();
+
+        const summaryText = document.querySelector('.selection-summary__text');
+
+        // click the first checkbox
+        helpers.triggerEvent(checkboxes[1], 'click');
+
+        expect(summaryText.textContent).toEqual("9 of 10 team members");
+
+      });
+
+    });
+
+    describe("from some to all the summary updates to reflect that", () => {
+
+      test("if fields are called 'folder'", () => {
+
+        formGroup.dataset.fieldLabel = 'folder';
+
+        checkAllCheckboxesButTheLast();
+
+        // start module
+        window.GOVUK.modules.start();
+
+        showCheckboxes();
+
+        const summaryText = document.querySelector('.selection-summary__text');
+
+        helpers.triggerEvent(checkboxes[0], 'click');
+
+        expect(summaryText.textContent).toEqual("All folders");
+
+      });
+
+      test("if fields are called 'team member'", () => {
+
+        formGroup.dataset.fieldLabel = 'team member';
+
+        checkAllCheckboxesButTheLast();
+
+        // start module
+        window.GOVUK.modules.start();
+
+        showCheckboxes();
+
+        const summaryText = document.querySelector('.selection-summary__text');
+
+        helpers.triggerEvent(checkboxes[0], 'click');
+
+        expect(summaryText.textContent).toEqual("All team members");
+
+      });
+
+    });
+
+  });
+
+});