diff --git a/tests/javascripts/previewPane.test.js b/tests/javascripts/previewPane.test.js
new file mode 100644
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--- /dev/null
+++ b/tests/javascripts/previewPane.test.js
@@ -0,0 +1,234 @@
+const helpers = require('./support/helpers.js');
+
+const emailPageURL = '/services/6658542f-0cad-491f-bec8-ab8457700ead/service-settings/set-email-branding';
+const emailPreviewConfirmationURL = '/services/6658542f-0cad-491f-bec8-ab8457700ead/service-settings/preview-email-branding';
+const letterPageURL = '/services/6658542f-0cad-491f-bec8-ab8457700ead/service-settings/set-letter-branding';
+const letterPreviewConfirmationURL = '/services/6658542f-0cad-491f-bec8-ab8457700ead/service-settings/preview-letter-branding';
+
+let locationMock;
+
+beforeAll(() => {
+
+  // mock calls to window.location
+  // default to the email page, the pathname can be changed inside specific tests
+  locationMock = new helpers.LocationMock(emailPageURL);
+
+});
+
+afterAll(() => {
+
+  // reset window.location to its original state
+  locationMock.reset();
+  require('./support/teardown.js');
+
+});
+
+describe('Preview pane', () => {
+
+  let form;
+  let radios;
+
+  beforeEach(() => {
+
+    const brands = {
+      "name": "branding_style",
+      "label": "Branding style",
+      "cssClasses": [],
+      "fields": [
+        {
+          "label": "Department for Education",
+          "value": "dfe",
+          "checked": true
+        },
+        {
+          "label": "Home Office",
+          "value": "ho",
+          "checked": false
+        },
+        {
+          "label": "Her Majesty's Revenue and Customs",
+          "value": "hmrc",
+          "checked": false
+        },
+        {
+          "label": "Department for Work and Pensions",
+          "value": "dwp",
+          "checked": false
+        }
+      ]
+    };
+
+    // set up DOM
+    document.body.innerHTML =
+      `<form method="post" action="${emailPageURL}" autocomplete="off" data-preview-type="email" novalidate>
+        <div class="grid-row"></div>
+        <div class="grid-row">
+          <div class="column-full">
+            <div data-module="autofocus">
+              <div class="live-search js-header" data-module="live-search" data-targets=".multiple-choice">
+                <div class="form-group">
+                  <label class="form-label" for="search">
+                      Search branding styles by name
+                  </label>
+                  <input autocomplete="off" class="form-control form-control-1-1 " id="search" name="search" required="" rows="8" type="search" value="">
+                </div>
+              </div>
+            </div> 
+          </div>
+        </div>
+        <div class="page-footer">
+          <button type="submit" class="button">Preview</button>
+        </div>
+      </form>`;
+
+    document.querySelector('.column-full').appendChild(helpers.getRadioGroup(brands));
+    form = document.querySelector('form');
+    radios = form.querySelector('fieldset');
+
+  });
+
+  afterEach(() => {
+
+    document.body.innerHTML = '';
+
+    // we run the previewPane.js script every test
+    // the module cache needs resetting each time for the script to execute
+    jest.resetModules();
+
+  });
+
+  describe("If the page type is 'email'", () => {
+
+    describe("When the page loads", () => {
+
+      test("it should add the preview pane", () => {
+
+        // run preview pane script
+        require('../../app/assets/javascripts/previewPane.js');
+
+        expect(document.querySelector('iframe')).not.toBeNull();
+
+      });
+
+      test("it should change the form to submit the selection instead of posting to a preview page", () => {
+
+        // run preview pane script
+        require('../../app/assets/javascripts/previewPane.js');
+
+        expect(form.getAttribute('action')).toEqual(emailPreviewConfirmationURL);
+
+      });
+
+      test("the preview pane should show the page for the selected brand", () => {
+
+        // run preview pane script
+        require('../../app/assets/javascripts/previewPane.js');
+
+        const selectedValue = Array.from(radios.querySelectorAll('input[type=radio]')).filter(radio => radio.checked)[0].value;
+
+        expect(document.querySelector('iframe').getAttribute('src')).toEqual(`/_email?branding_style=${selectedValue}`);
+
+      });
+
+      test("the submit button should change from 'Preview' to 'Save'", () => {
+
+        // run preview pane script
+        require('../../app/assets/javascripts/previewPane.js');
+
+        expect(document.querySelector('button[type=submit]').textContent).toEqual('Save');
+
+      });
+
+    });
+
+    describe("If the selection changes", () => {
+
+      test("the page shown should match the selected brand", () => {
+
+        // run preview pane script
+        require('../../app/assets/javascripts/previewPane.js');
+
+        const newSelection = radios.querySelectorAll('input[type=radio]')[1];
+
+        helpers.moveSelectionToRadio(newSelection);
+
+        expect(document.querySelector('iframe').getAttribute('src')).toEqual(`/_email?branding_style=${newSelection.value}`);
+
+      });
+
+    });
+
+  });
+
+  describe("If the page type is 'letter'", () => {
+
+    beforeEach(() => {
+
+      // set page URL and page type to 'letter'
+      window.location.pathname = letterPreviewConfirmationURL;
+      form.setAttribute('data-preview-type', 'letter');
+
+    });
+
+    describe("When the page loads", () => {
+
+      test("it should add the preview pane", () => {
+
+        // run preview pane script
+        require('../../app/assets/javascripts/previewPane.js');
+
+        expect(document.querySelector('iframe')).not.toBeNull();
+
+      });
+
+      test("it should change the form to submit the selection instead of posting to a preview page", () => {
+
+        // run preview pane script
+        require('../../app/assets/javascripts/previewPane.js');
+
+        expect(form.getAttribute('action')).toEqual(letterPreviewConfirmationURL);
+
+      });
+
+      test("the preview pane should show the page for the selected brand", () => {
+
+        // run preview pane script
+        require('../../app/assets/javascripts/previewPane.js');
+
+        const selectedValue = Array.from(radios.querySelectorAll('input[type=radio]')).filter(radio => radio.checked)[0].value;
+
+        expect(document.querySelector('iframe').getAttribute('src')).toEqual(`/_letter?branding_style=${selectedValue}`);
+
+      });
+
+      test("the submit button should change from 'Preview' to 'Save'", () => {
+
+        // run preview pane script
+        require('../../app/assets/javascripts/previewPane.js');
+
+        expect(document.querySelector('button[type=submit]').textContent).toEqual('Save');
+
+      });
+
+    });
+
+    describe("If the selection changes", () => {
+
+      test("the page shown should match the selected brand", () => {
+
+        // run preview pane script
+        require('../../app/assets/javascripts/previewPane.js');
+
+        const newSelection = radios.querySelectorAll('input[type=radio]')[1];
+
+        helpers.moveSelectionToRadio(newSelection);
+
+        expect(document.querySelector('iframe').getAttribute('src')).toEqual(`/_letter?branding_style=${newSelection.value}`);
+
+      });
+
+    });
+
+  });
+
+});