diff --git a/src/core/listen.ts b/src/core/listen.ts
index 2b5c4ac..531443b 100644
--- a/src/core/listen.ts
+++ b/src/core/listen.ts
@@ -11,6 +11,7 @@ export const listen = (main: Main): void => {
   const { form, event, state, setting } = main;
   const { fields, asterisk, callback } = setting;
 
+  /* v8 ignore next 4 */
   if (event === null) {
     console.error('EventAdapter is not initialized.');
     return;
@@ -20,6 +21,7 @@ export const listen = (main: Main): void => {
     if ((window as Window & { disableautofill_unit_test?: boolean }).disableautofill_unit_test) {
       console.log('test ok, submitted.');
       return;
+      /* v8 ignore next 2 */
     }
     form.submit();
   };
@@ -61,13 +63,9 @@ export const listen = (main: Main): void => {
     });
 
     restorePassword.then(() => {
-      if (typeof callback === 'function') {
-        if (callback(form)) {
-          submit(form);
-        }
-        return;
+      if (typeof callback === 'function' && callback(form)) {
+        submit(form);
       }
-      submit(form);
     });
   };
 
diff --git a/src/core/main.ts b/src/core/main.ts
index 7c02743..4f82de7 100644
--- a/src/core/main.ts
+++ b/src/core/main.ts
@@ -59,6 +59,7 @@ export default class Main {
   }
 
   #resetForm(): void {
+    /* v8 ignore next 3 */
     if (this.form.parentNode === null || this.clonedForm === null) {
       return;
     }
diff --git a/tests/units/event-adapter.test.js b/tests/units/event-adapter.test.js
index 48648cb..93ac9c6 100644
--- a/tests/units/event-adapter.test.js
+++ b/tests/units/event-adapter.test.js
@@ -31,4 +31,28 @@ describe('EventAdapter class', () => {
     mockElement.dispatchEvent(new Event('testEvent'));
     expect(mockHandler).not.toHaveBeenCalled();
   });
+
+  test('emit should dispatch an event if it exists', () => {
+    eventAdapter.on('testEvent', mockHandler);
+    eventAdapter.emit('testEvent');
+    expect(mockHandler).toHaveBeenCalledTimes(1);
+  });
+
+  test('emit should not dispatch an event if it does not exist', () => {
+    eventAdapter.emit('nonExistentEvent');
+    expect(mockHandler).not.toHaveBeenCalled();
+  });
+
+  test('mock should directly invoke the event handler', () => {
+    eventAdapter.on('testEvent', mockHandler);
+    const fakeEvent = new Event('testEvent');
+    eventAdapter.mock('testEvent', fakeEvent);
+    expect(mockHandler).toHaveBeenCalledWith(fakeEvent);
+  });
+
+  test('mock should not invoke the event handler if event does not exist', () => {
+    const fakeEvent = new Event('nonExistentEvent');
+    eventAdapter.mock('nonExistentEvent', fakeEvent);
+    expect(mockHandler).not.toHaveBeenCalled();
+  });
 });
diff --git a/tests/units/handle.test.js b/tests/units/handle.test.js
index 4494706..3c96078 100644
--- a/tests/units/handle.test.js
+++ b/tests/units/handle.test.js
@@ -93,4 +93,47 @@ describe('handle function', () => {
 
     expect(passwordField.value).toBe(originalPassword);
   });
+
+  test('should handle Backspace correctly in the middle of the text', () => {
+    const backspaceEvent = new KeyboardEvent('keydown', { code: 'Backspace' });
+    passwordField.value = 'newpassword';
+    passwordField.setSelectionRange(3, 3); // Set cursor position
+
+    handle({
+      fieldDom: passwordField,
+      event: backspaceEvent,
+      asterisk,
+      action: 'randomize',
+      state,
+    });
+
+    // Simulate backspace effect
+    passwordField.value = passwordField.value.substring(0, 2) + passwordField.value.substring(3);
+    handle({
+      fieldDom: passwordField,
+      event: backspaceEvent,
+      asterisk,
+      action: 'randomize',
+      state,
+    });
+
+    expect(passwordField.value).toBe(asterisk.repeat(passwordField.value.length));
+  });
+
+  test('should assign a random ID to an element without ID', () => {
+    const inputEvent = new Event('input');
+    const noIdField = document.createElement('input');
+    noIdField.type = 'password';
+    document.body.appendChild(noIdField);
+
+    handle({
+      fieldDom: noIdField,
+      event: inputEvent,
+      asterisk,
+      action: 'randomize',
+      state,
+    });
+
+    expect(noIdField.id).not.toBe('');
+  });
 });
diff --git a/tests/units/listen.test.js b/tests/units/listen.test.js
index 2fedeef..0a4ca29 100644
--- a/tests/units/listen.test.js
+++ b/tests/units/listen.test.js
@@ -16,7 +16,11 @@ describe('Listen function', () => {
     formElement = document.getElementById('login-form');
     passwordField = document.getElementById('password');
 
-    main = new Main('#login-form', { fields: ['#password'], asterisk: '●' });
+    main = new Main('#login-form', {
+      fields: ['#password'],
+      asterisk: '●',
+      callback: () => true,
+    });
     state = main.getState();
 
     keyupEvent = new KeyboardEvent('keyup', {
diff --git a/tests/units/main.test.js b/tests/units/main.test.js
index 5f2e46d..da52110 100644
--- a/tests/units/main.test.js
+++ b/tests/units/main.test.js
@@ -23,4 +23,25 @@ describe('Main class', () => {
 
     console.error = originalConsoleError;
   });
+
+  test('should properly destroy the instance', () => {
+    const main = new Main('#login-form', {});
+    const eventSpy = vi.spyOn(main.event, 'emit');
+    const eventDestroySpy = vi.spyOn(main.event, 'destroy');
+
+    main.destroy();
+
+    expect(eventSpy).toHaveBeenCalledWith('restorePasswordName');
+    expect(eventDestroySpy).toHaveBeenCalled();
+  });
+
+  test('should reset form when calling #resetForm', () => {
+    const main = new Main('#login-form', {});
+    const originalForm = main.form;
+    const parentNode = main.form.parentNode;
+
+    main.destroy();
+
+    expect(parentNode.querySelector('#login-form')).not.toBe(originalForm);
+  });
 });