diff --git a/tests/javascripts/errorBanner.test.js b/tests/javascripts/errorBanner.test.js
index 55affdc7d..932826043 100644
--- a/tests/javascripts/errorBanner.test.js
+++ b/tests/javascripts/errorBanner.test.js
@@ -1,6 +1,11 @@
 beforeAll(() => {
-  // ErrorBanner module sets window.NotifyModules.ErrorBanner for backward compatibility
+  const originalNotifyModules = window.NotifyModules;
+  delete window.NotifyModules;
+
   require('../../app/assets/javascripts/errorBanner.js');
+
+  expect(window.NotifyModules).toBeDefined();
+  expect(window.NotifyModules.ErrorBanner).toBeDefined();
 });
 
 afterAll(() => {
@@ -20,6 +25,13 @@ describe("Error Banner", () => {
       window.NotifyModules.ErrorBanner.hideBanner();
       expect(document.querySelector('.banner-dangerous').classList).toContain('display-none')
     });
+
+    test("Will not error when no banner elements exist", () => {
+      document.body.innerHTML = `<div>No banners here</div>`;
+      expect(() => {
+        window.NotifyModules.ErrorBanner.hideBanner();
+      }).not.toThrow();
+    });
   });
 
   describe("The `showBanner` method", () => {
@@ -34,6 +46,13 @@ describe("Error Banner", () => {
     test("Will show the element", () => {
       expect(document.querySelector('.banner-dangerous').classList).not.toContain('display-none')
     });
+
+    test("Will not error when no banner elements exist", () => {
+      document.body.innerHTML = `<div>No banners here</div>`;
+      expect(() => {
+        window.NotifyModules.ErrorBanner.showBanner();
+      }).not.toThrow();
+    });
   });
 
   test("Module exports ErrorBanner to window.NotifyModules", () => {
diff --git a/tests/javascripts/fileUpload.test.js b/tests/javascripts/fileUpload.test.js
index 2d8bf06f9..f02c48880 100644
--- a/tests/javascripts/fileUpload.test.js
+++ b/tests/javascripts/fileUpload.test.js
@@ -184,4 +184,15 @@ describe('announceUploadStatusFromElement', () => {
     // Still unchanged
     expect(srRegion.textContent).toBe('Old message');
   });
+
+  test('does nothing if upload-status-live element does not exist', () => {
+    document.body.innerHTML = `
+      <span id="upload-error" class="usa-sr-only">File upload failed</span>
+    `;
+
+    expect(() => {
+      announceUploadStatusFromElement();
+      jest.advanceTimersByTime(300);
+    }).not.toThrow();
+  });
 });
diff --git a/tests/javascripts/listEntry.test.js b/tests/javascripts/listEntry.test.js
index 176949eea..e4fac6859 100644
--- a/tests/javascripts/listEntry.test.js
+++ b/tests/javascripts/listEntry.test.js
@@ -420,4 +420,23 @@ describe("List entry", () => {
       expect(inputList.innerHTML).toContain('id="test-2"');
     });
   });
+
+  describe("when the container element has no id attribute", () => {
+    test("the module should not initialize", () => {
+      document.body.innerHTML = `
+        <div class="input-list" data-module="list-entry" data-list-item-name="domain">
+          <div class="list-entry">
+            <input type="text" name="domains-1" class="usa-input">
+          </div>
+        </div>`;
+
+      const inputList = document.querySelector('[data-module="list-entry"]');
+
+      expect(() => {
+        window.NotifyModules.start();
+      }).not.toThrow();
+
+      expect(inputList.querySelector('.input-list__button--add')).toBeNull();
+    });
+  });
 });
diff --git a/tests/javascripts/liveSearch.test.js b/tests/javascripts/liveSearch.test.js
index c0918fbd2..570b6170c 100644
--- a/tests/javascripts/liveSearch.test.js
+++ b/tests/javascripts/liveSearch.test.js
@@ -276,4 +276,133 @@ describe('Live search', () => {
 
   });
 
+  describe("When items have checked checkboxes", () => {
+
+    beforeEach(() => {
+
+      const users = [
+        {
+          "label": "Template editor",
+          "email": "template-editor@nhs.uk",
+          "permissions" : ["Add and edit templates"],
+          "checked": true
+        },
+        {
+          "label": "Administrator",
+          "email": "admin@nhs.uk",
+          "permissions" : ["Send messages", "Add and edit templates", "Manage settings, team and usage", "API integration"],
+          "checked": false
+        }
+      ];
+
+      document.body.innerHTML = `
+        <div class="live-search js-header" data-module="live-search" data-targets=".user-list-item">
+          <div class="form-group" data-module="">
+            <label class="form-label" for="search">
+                ${searchLabelText}
+            </label>
+            <input autocomplete="off" class="form-control form-control-1-1 " data-module="" id="search" name="search" rows="8" type="search" value="">
+            <div role="region" aria-live="polite" class="live-search__status usa-sr-only"></div>
+          </div>
+        </div>
+        <form method="post" autocomplete="off" novalidate>
+          <div class="user-list-item">
+            <input type="checkbox" checked>
+            <span class="live-search-relevant">${users[0].label} (${users[0].email})</span>
+          </div>
+          <div class="user-list-item">
+            <input type="checkbox">
+            <span class="live-search-relevant">${users[1].label} (${users[1].email})</span>
+          </div>
+        </form>`;
+
+      searchTextbox = document.getElementById('search');
+      liveRegion = document.querySelector('.live-search__status');
+      list = document.querySelector('form');
+
+    });
+
+    test("Items with checked checkboxes should always be visible", () => {
+
+      searchTextbox.value = 'Administrator';
+
+      window.NotifyModules.start();
+
+      const listItems = list.querySelectorAll('.user-list-item');
+      const listItemsShowing = Array.from(listItems).filter(item => !item.classList.contains('js-hidden'));
+
+      expect(listItemsShowing.length).toEqual(2);
+
+    });
+
+  });
+
+  describe("When no results message element exists", () => {
+
+    beforeEach(() => {
+
+      document.body.innerHTML = `
+        <div class="live-search js-header" data-module="live-search" data-targets=".user-list-item">
+          <div class="form-group" data-module="">
+            <label class="form-label" for="search">
+                ${searchLabelText}
+            </label>
+            <input autocomplete="off" class="form-control form-control-1-1 " data-module="" id="search" name="search" rows="8" type="search" value="">
+            <div role="region" aria-live="polite" class="live-search__status usa-sr-only"></div>
+          </div>
+          <div class="js-live-search-no-results js-hidden">No results found</div>
+        </div>
+        <form method="post" autocomplete="off" novalidate>
+          <div class="user-list-item">
+            <span class="live-search-relevant">Test User (test@example.com)</span>
+          </div>
+        </form>`;
+
+      searchTextbox = document.getElementById('search');
+      liveRegion = document.querySelector('.live-search__status');
+      list = document.querySelector('form');
+
+    });
+
+    test("No results message should show when search yields no results", () => {
+
+      searchTextbox.value = 'nomatch';
+
+      window.NotifyModules.start();
+
+      const noResultsMessage = document.querySelector('.js-live-search-no-results');
+      expect(noResultsMessage.classList.contains('js-hidden')).toBe(false);
+
+    });
+
+    test("No results message should hide when search yields results", () => {
+
+      searchTextbox.value = 'nomatch';
+      window.NotifyModules.start();
+
+      let noResultsMessage = document.querySelector('.js-live-search-no-results');
+      expect(noResultsMessage.classList.contains('js-hidden')).toBe(false);
+
+      searchTextbox.value = 'Test';
+      helpers.triggerEvent(searchTextbox, 'input');
+
+      expect(noResultsMessage.classList.contains('js-hidden')).toBe(true);
+
+    });
+
+    test("No results message should hide when search is empty", () => {
+
+      searchTextbox.value = 'nomatch';
+      window.NotifyModules.start();
+
+      searchTextbox.value = '';
+      helpers.triggerEvent(searchTextbox, 'input');
+
+      const noResultsMessage = document.querySelector('.js-live-search-no-results');
+      expect(noResultsMessage.classList.contains('js-hidden')).toBe(true);
+
+    });
+
+  });
+
 });
diff --git a/tests/javascripts/notifyModal.test.js b/tests/javascripts/notifyModal.test.js
index be703fd97..5e8156194 100644
--- a/tests/javascripts/notifyModal.test.js
+++ b/tests/javascripts/notifyModal.test.js
@@ -159,3 +159,70 @@ describe("Modal trigger buttons", () => {
       expect(modalWrapper.classList.contains("is-hidden")).toBe(true);
     });
   });
+
+describe("Modal edge cases", () => {
+  test("openModal does nothing if wrapper doesn't exist", () => {
+    expect(() => {
+      openModal("nonExistentModal");
+    }).not.toThrow();
+  });
+
+  test("openModal does nothing if modal element doesn't exist inside wrapper", () => {
+    document.body.innerHTML = `<div id="emptyWrapper"></div>`;
+    expect(() => {
+      openModal("emptyWrapper");
+    }).not.toThrow();
+  });
+
+  test("openModal works when there is no focusable element", () => {
+    document.body.innerHTML = `
+      <div id="noFocusModal">
+        <div class="usa-modal">
+          <p>No focusable elements here</p>
+        </div>
+      </div>
+    `;
+    expect(() => {
+      openModal("noFocusModal");
+    }).not.toThrow();
+    expect(document.getElementById("noFocusModal").classList.contains("is-hidden")).toBe(false);
+  });
+
+  test("closeModal does nothing if no modal is active", () => {
+    expect(() => {
+      closeModal();
+    }).not.toThrow();
+  });
+
+  test("closeModal handles case where modal element is missing", () => {
+    document.body.innerHTML = `
+      <button data-open-modal="testModal">Open</button>
+      <div id="testModal"></div>
+    `;
+    openModal("testModal");
+    expect(() => {
+      closeModal();
+    }).not.toThrow();
+  });
+
+  test("Modal keydown handler ignores non-Tab keys", () => {
+    document.body.innerHTML = `
+      <div id="keyModal">
+        <div class="usa-modal">
+          <button>Test</button>
+        </div>
+      </div>
+    `;
+    openModal("keyModal");
+    const modal = document.querySelector(".usa-modal");
+
+    const enterEvent = new KeyboardEvent("keydown", {
+      key: "Enter",
+      bubbles: true
+    });
+
+    expect(() => {
+      modal.dispatchEvent(enterEvent);
+    }).not.toThrow();
+  });
+});
diff --git a/tests/javascripts/preventDuplicateFormSubmissions.test.js b/tests/javascripts/preventDuplicateFormSubmissions.test.js
index af043b3e6..450ef483f 100644
--- a/tests/javascripts/preventDuplicateFormSubmissions.test.js
+++ b/tests/javascripts/preventDuplicateFormSubmissions.test.js
@@ -65,5 +65,140 @@ describe('Prevent duplicate form submissions', () => {
 
   });
 
+  test("It should not error when form has no submit button", () => {
+
+    document.body.innerHTML = `
+      <form action="/" method="post">
+        <input type="text" name="test">
+      </form>`;
+
+    form = document.querySelector('form');
+    formEventSpy = helpers.spyOnFormSubmitEventPrevention(jest, form);
+
+    jest.resetModules();
+    require('../../app/assets/javascripts/preventDuplicateFormSubmissions.js');
+
+    expect(() => {
+      helpers.triggerEvent(form, 'submit');
+    }).not.toThrow();
+
+  });
+
+  test("It should disable and add spinner to 'send' button", () => {
+
+    document.body.innerHTML = `
+      <form action="/" method="post">
+        <button class="usa-button" type="submit" name="send">Send</button>
+      </form>`;
+
+    form = document.querySelector('form');
+    button = document.querySelector('button');
+    formEventSpy = helpers.spyOnFormSubmitEventPrevention(jest, form);
+
+    jest.resetModules();
+    require('../../app/assets/javascripts/preventDuplicateFormSubmissions.js');
+
+    helpers.triggerEvent(button, 'click');
+
+    jest.advanceTimersByTime(100);
+
+    expect(button.disabled).toBe(true);
+    expect(button.getAttribute('aria-busy')).toBe('true');
+    expect(button.querySelector('.loading-spinner')).not.toBeNull();
+
+  });
+
+  test("It should disable and add spinner to 'schedule' button", () => {
+
+    document.body.innerHTML = `
+      <form action="/" method="post">
+        <button class="usa-button" type="submit" name="schedule">Schedule</button>
+      </form>`;
+
+    form = document.querySelector('form');
+    button = document.querySelector('button');
+    formEventSpy = helpers.spyOnFormSubmitEventPrevention(jest, form);
+
+    jest.resetModules();
+    require('../../app/assets/javascripts/preventDuplicateFormSubmissions.js');
+
+    helpers.triggerEvent(button, 'click');
+
+    jest.advanceTimersByTime(100);
+
+    expect(button.disabled).toBe(true);
+    expect(button.getAttribute('aria-busy')).toBe('true');
+    expect(button.querySelector('.loading-spinner')).not.toBeNull();
+
+  });
+
+  test("It should disable both send and cancel buttons when send is clicked", () => {
+
+    document.body.innerHTML = `
+      <form action="/" method="post">
+        <button class="usa-button" type="submit" name="send">Send</button>
+        <button class="usa-button" type="submit" name="cancel">Cancel</button>
+      </form>`;
+
+    form = document.querySelector('form');
+    const sendButton = document.querySelector('button[name="send"]');
+    const cancelButton = document.querySelector('button[name="cancel"]');
+    formEventSpy = helpers.spyOnFormSubmitEventPrevention(jest, form);
+
+    jest.resetModules();
+    require('../../app/assets/javascripts/preventDuplicateFormSubmissions.js');
+
+    helpers.triggerEvent(sendButton, 'click');
+
+    jest.advanceTimersByTime(100);
+
+    expect(sendButton.disabled).toBe(true);
+    expect(cancelButton.disabled).toBe(true);
+
+  });
+
+  test("It should not add duplicate spinner if one already exists", () => {
+
+    document.body.innerHTML = `
+      <form action="/" method="post">
+        <button class="usa-button" type="submit" name="send">Send<span class="loading-spinner"></span></button>
+      </form>`;
+
+    form = document.querySelector('form');
+    button = document.querySelector('button');
+    formEventSpy = helpers.spyOnFormSubmitEventPrevention(jest, form);
+
+    jest.resetModules();
+    require('../../app/assets/javascripts/preventDuplicateFormSubmissions.js');
+
+    helpers.triggerEvent(button, 'click');
+
+    jest.advanceTimersByTime(100);
+
+    expect(button.querySelectorAll('.loading-spinner').length).toBe(1);
+
+  });
+
+  test("It should handle button with no name attribute", () => {
+
+    document.body.innerHTML = `
+      <form action="/" method="post">
+        <button class="usa-button" type="submit">Submit</button>
+      </form>`;
+
+    form = document.querySelector('form');
+    button = document.querySelector('button');
+    formEventSpy = helpers.spyOnFormSubmitEventPrevention(jest, form);
+
+    jest.resetModules();
+    require('../../app/assets/javascripts/preventDuplicateFormSubmissions.js');
+
+    expect(() => {
+      helpers.triggerEvent(button, 'click');
+      jest.advanceTimersByTime(1600);
+    }).not.toThrow();
+
+  });
+
 
 });
diff --git a/tests/javascripts/radioSelect.test.js b/tests/javascripts/radioSelect.test.js
index 9e67288a0..387efe5ae 100644
--- a/tests/javascripts/radioSelect.test.js
+++ b/tests/javascripts/radioSelect.test.js
@@ -434,6 +434,17 @@ describe('RadioSelect', () => {
 
     });
 
+    test("clicking the 'Done' button without selecting an option should reset to default state", () => {
+
+      const doneButton = document.querySelector('.radio-select__column:nth-child(2) input[type=button]');
+
+      helpers.triggerEvent(doneButton, 'click');
+
+      const categoryButtons = document.querySelectorAll('.radio-select__column:nth-child(2) .radio-select__button--category');
+      expect(categoryButtons.length).toBeGreaterThan(0);
+
+    });
+
     describe("after selecting an option clicking the 'Choose a different time' button should", () => {
 
       beforeEach(() => {
diff --git a/tests/javascripts/timeoutPopup.test.js b/tests/javascripts/timeoutPopup.test.js
index 1afea4b86..26d35a1f1 100644
--- a/tests/javascripts/timeoutPopup.test.js
+++ b/tests/javascripts/timeoutPopup.test.js
@@ -135,4 +135,37 @@ describe('The session timer ', () => {
     window.NotifyModules.TimeoutPopup.checkTimer();
     expect(checkTimerMock).toHaveBeenCalled();
   });
+
+  test('checkTimer expires and redirects when time runs out', () => {
+    const restore = mockWindowLocation();
+    const sessionTimer = document.getElementById('sessionTimer');
+    sessionTimer.showModal = jest.fn();
+    sessionTimer.close = jest.fn();
+
+    const closeTimerMock = jest.spyOn(sessionTimer, 'close');
+
+    const pastTime = new Date().getTime() - 1000;
+
+    window.NotifyModules.TimeoutPopup.checkTimer(pastTime);
+
+    expect(closeTimerMock).toHaveBeenCalled();
+
+    restore();
+  });
+
+  test('checkTimer updates time display and shows modal when time is remaining', () => {
+    const sessionTimer = document.getElementById('sessionTimer');
+    const timeLeftElement = document.getElementById('timeLeft');
+    sessionTimer.showModal = jest.fn();
+    sessionTimer.close = jest.fn();
+
+    const showModalMock = jest.spyOn(sessionTimer, 'showModal');
+
+    const futureTime = new Date().getTime() + (2 * 60 * 1000);
+
+    window.NotifyModules.TimeoutPopup.checkTimer(futureTime);
+
+    expect(showModalMock).toHaveBeenCalled();
+    expect(timeLeftElement.textContent).toMatch(/\d+m \d+s/);
+  });
 });
diff --git a/tests/javascripts/updateStatus.test.js b/tests/javascripts/updateStatus.test.js
index 30c53384e..0504db2e8 100644
--- a/tests/javascripts/updateStatus.test.js
+++ b/tests/javascripts/updateStatus.test.js
@@ -179,4 +179,25 @@ describe('Update content', () => {
 
   });
 
+  test("It should handle fetch errors gracefully", async () => {
+
+    global.fetch.mockImplementationOnce(() =>
+      Promise.resolve({
+        ok: false,
+        status: 500,
+        json: () => Promise.resolve({})
+      })
+    );
+
+    window.NotifyModules.start();
+
+    const textbox = document.getElementById('template_content');
+    helpers.triggerEvent(textbox, 'input');
+
+    jest.runAllTimers();
+
+    expect(document.querySelector('[data-module="update-status"]')).not.toBeNull();
+
+  });
+
 });