diff --git a/js/renovation/button.tsx b/js/renovation/button.tsx
index 5904ff098739..6f7ddd5903b5 100644
--- a/js/renovation/button.tsx
+++ b/js/renovation/button.tsx
@@ -24,7 +24,7 @@ import BaseComponent from './preact-wrapper/button';
 const stylingModes = ['outlined', 'text', 'contained'];
 
 const getInkRippleConfig = ({ text, icon, type }: ButtonProps) => {
-  const isOnlyIconButton = !text && icon || type === 'back';
+  const isOnlyIconButton = (!text && icon) || (type === 'back');
   const config: any = isOnlyIconButton ? {
     isCentered: true,
     useHoldAnimation: false,
diff --git a/package.json b/package.json
index da6a63c7baa6..c6bba5636594 100644
--- a/package.json
+++ b/package.json
@@ -156,7 +156,7 @@
   "scripts": {
     "lint": "npm-run-all -p -c lint-js lint-css",
     "lint-js": "eslint .",
-    "lint-ts": "eslint ./testing/jest/**/*.ts ./testing/jest/**/*.tsx ./js/renovation/**/*.tsx ./js/renovation/**/*.ts",
+    "lint-ts": "eslint ./js/renovation/*.{ts,tsx} ./js/renovation/**/*.{ts,tsx} ./testing/jest/**/*.{ts,tsx}",
     "lint-css": "stylelint styles",
     "lint-staged": "lint-staged && npm run lint-ts",
     "build": "dotnet build build/build-dotnet.sln && gulp default",
diff --git a/testing/jest/button.tests.tsx b/testing/jest/button.tests.tsx
index 5878dca16328..57ef06d24fb0 100644
--- a/testing/jest/button.tests.tsx
+++ b/testing/jest/button.tests.tsx
@@ -1,6 +1,7 @@
 
 import { h, createRef } from 'preact';
-import { mount, ReactWrapper, Element } from 'enzyme';
+import { mount, ReactWrapper } from 'enzyme';
+import { JSXInternal } from 'preact/src/jsx';
 import devices from '../../js/core/devices';
 import themes from '../../js/ui/themes';
 import {
@@ -17,6 +18,10 @@ import Button, { defaultOptions } from '../../js/renovation/button.p';
 import type ButtonRef from '../../js/renovation/button.p';
 import Icon from '../../js/renovation/icon.p';
 import Widget from '../../js/renovation/widget.p';
+import type { WidgetProps } from '../../js/renovation/widget';
+import type { ButtonProps } from '../../js/renovation/button';
+
+type Mock = jest.Mock;
 
 jest.mock('../../js/core/devices', () => {
   const actualDevices = require.requireActual('../../js/core/devices');
@@ -38,9 +43,10 @@ describe('Button', () => {
   const render = (props = {}): ReactWrapper => mount(<Button {...props} />).childAt(0);
 
   beforeEach(() => {
-    (devices.real as any).mockImplementation(() => ({ deviceType: 'desktop' }));
+    (devices.real as Mock).mockImplementation(() => ({ deviceType: 'desktop' }));
+    // eslint-disable-next-line @typescript-eslint/no-explicit-any
     (devices as any).isSimulator.mockImplementation(() => false);
-    (themes.current as any).mockImplementation(() => 'generic');
+    (themes.current as Mock).mockImplementation(() => 'generic');
   });
 
   afterEach(() => {
@@ -53,14 +59,14 @@ describe('Button', () => {
       describe('Wave position and size', () => {
         it('should calc correct position and size for the back button', () => {
           const button = render({ useInkRipple: true, type: 'back' });
-          const content: Element = button.find('.dx-button-content').getDOMNode();
-          const { onActive } = button.find(Widget).props();
+          const content = button.find('.dx-button-content').getDOMNode<HTMLDivElement>();
+          const { onActive } = button.find(Widget).props() as WidgetProps;
 
           content.style.width = '10px';
           content.style.height = '10px';
           onActive(fakeClickEvent);
 
-          const wave = content.querySelectorAll('.dx-inkripple-wave')[0];
+          const wave = content.querySelectorAll<HTMLDivElement>('.dx-inkripple-wave')[0];
 
           expect(wave.style).toMatchObject({
             left: '-2px', top: '-2px', width: '14px', height: '14px',
@@ -69,14 +75,14 @@ describe('Button', () => {
 
         it('should calc correct position and size for the icon only button', () => {
           const button = render({ useInkRipple: true, text: '', icon: 'icon' });
-          const content: Element = button.find('.dx-button-content').getDOMNode();
-          const { onActive } = button.find(Widget).props();
+          const content = button.find('.dx-button-content').getDOMNode<HTMLDivElement>();
+          const { onActive } = button.find(Widget).props() as WidgetProps;
 
           content.style.width = '10px';
           content.style.height = '10px';
           onActive(fakeClickEvent);
 
-          const wave = content.querySelectorAll('.dx-inkripple-wave')[0];
+          const wave = content.querySelectorAll<HTMLDivElement>('.dx-inkripple-wave')[0];
 
           expect(wave.style).toMatchObject({
             left: '-2px', top: '-2px', width: '14px', height: '14px',
@@ -85,14 +91,14 @@ describe('Button', () => {
 
         it('should calc correct position and size for the regular button', () => {
           const button = render({ useInkRipple: true });
-          const content: Element = button.find('.dx-button-content').getDOMNode();
-          const { onActive } = button.find(Widget).props();
+          const content = button.find('.dx-button-content').getDOMNode<HTMLDivElement>();
+          const { onActive } = button.find(Widget).props() as WidgetProps;
 
           content.style.width = '10px';
           content.style.height = '10px';
           onActive(fakeClickEvent);
 
-          const wave = content.querySelectorAll('.dx-inkripple-wave')[0];
+          const wave = content.querySelectorAll<HTMLDivElement>('.dx-inkripple-wave')[0];
 
           expect(wave.style).toMatchObject({
             left: '-14px', top: '-14px', width: '28px', height: '28px',
@@ -102,8 +108,8 @@ describe('Button', () => {
 
       it('should be `false` by default', () => {
         const button = render();
-        const content: Element = button.find('.dx-button-content').getDOMNode();
-        const { onActive } = button.find(Widget).props();
+        const content = button.find('.dx-button-content').getDOMNode<HTMLDivElement>();
+        const { onActive } = button.find(Widget).props() as WidgetProps;
 
         onActive(defaultEvent);
         expect(content.querySelectorAll('.dx-inkripple')).toHaveLength(0);
@@ -112,7 +118,7 @@ describe('Button', () => {
       it('should render on active event and clear on inactive event', () => {
         const button = render({ useInkRipple: true });
         const content: Element = button.find('.dx-button-content').getDOMNode();
-        const { onActive, onInactive } = button.find(Widget).props();
+        const { onActive, onInactive } = button.find(Widget).props() as WidgetProps;
 
         expect(content.querySelectorAll('.dx-inkripple-wave')).toHaveLength(0);
         expect(content.querySelectorAll('.dx-inkripple-hiding')).toHaveLength(0);
@@ -146,7 +152,7 @@ describe('Button', () => {
         const submitInput = button.find('input.dx-button-submit-input');
         const submitInputClick = jest.fn();
 
-        (submitInput.getDOMNode() as Element).click = submitInputClick;
+        submitInput.getDOMNode<HTMLInputElement>().click = submitInputClick;
         expect(submitInputClick).toHaveBeenCalledTimes(0);
         emit(EVENT.dxClick, defaultEvent, button.getDOMNode());
         expect(submitInputClick).toHaveBeenCalledTimes(1);
@@ -157,7 +163,7 @@ describe('Button', () => {
         const submitInput = button.find('input.dx-button-submit-input');
         const submitInputClick = jest.fn();
 
-        (submitInput.getDOMNode() as Element).click = submitInputClick;
+        submitInput.getDOMNode<HTMLInputElement>().click = submitInputClick;
         expect(submitInputClick).toHaveBeenCalledTimes(0);
         emitKeyboard(KEY.enter);
         expect(submitInputClick).toHaveBeenCalledTimes(1);
@@ -165,17 +171,17 @@ describe('Button', () => {
 
       it('should submit form by space press', () => {
         const button = render({ useSubmitBehavior: true });
-        const submitInput = button.find('input.dx-button-submit-input');
+        const submitInput = button.find('input.dx-button-submit-input').getDOMNode<HTMLInputElement>();
         const submitInputClick = jest.fn();
 
-        submitInput.getDOMNode().click = submitInputClick;
+        submitInput.click = submitInputClick;
         expect(submitInputClick).toHaveBeenCalledTimes(0);
         emitKeyboard(KEY.space);
         expect(submitInputClick).toHaveBeenCalledTimes(1);
       });
 
       it('should stop event propagation', () => {
-        const onSubmit = ({ event }) => event.stopPropagation();
+        const onSubmit = ({ event }): boolean => event.stopPropagation();
         const button = render({ useSubmitBehavior: true, onSubmit });
         const submitInput = button.find('input.dx-button-submit-input');
         const e = { ...defaultEvent, stopPropagation: jest.fn() };
@@ -188,7 +194,7 @@ describe('Button', () => {
 
     describe('stylingMode', () => {
       it('should use `contained` as a default value', () => {
-        const classNames = render().prop('classes');
+        const classNames = render().prop('classes') as string[];
 
         expect(classNames.includes('dx-button-mode-contained')).toBe(true);
         expect(classNames.includes('dx-button-mode-text')).toBe(false);
@@ -196,7 +202,7 @@ describe('Button', () => {
       });
 
       it('should add `dx-button-mode-text` class if the stylingMode is `text`', () => {
-        const classNames = render({ stylingMode: 'text' }).prop('classes');
+        const classNames = render({ stylingMode: 'text' }).prop('classes') as string[];
 
         expect(classNames.includes('dx-button-mode-text')).toBe(true);
         expect(classNames.includes('dx-button-mode-contained')).toBe(false);
@@ -204,7 +210,7 @@ describe('Button', () => {
       });
 
       it('should add `dx-button-mode-contained` class if the stylingMode is `contained`', () => {
-        const classNames = render({ stylingMode: 'contained' }).prop('classes');
+        const classNames = render({ stylingMode: 'contained' }).prop('classes') as string[];
 
         expect(classNames.includes('dx-button-mode-contained')).toBe(true);
         expect(classNames.includes('dx-button-mode-text')).toBe(false);
@@ -212,7 +218,7 @@ describe('Button', () => {
       });
 
       it('should add `dx-button-mode-outlined` class if the stylingMode is `outlined`', () => {
-        const classNames = render({ stylingMode: 'outlined' }).prop('classes');
+        const classNames = render({ stylingMode: 'outlined' }).prop('classes') as string[];
 
         expect(classNames.includes('dx-button-mode-outlined')).toBe(true);
         expect(classNames.includes('dx-button-mode-text')).toBe(false);
@@ -228,7 +234,7 @@ describe('Button', () => {
       });
 
       it('should not render `text` by default', () => {
-        const classNames = render().prop('classes');
+        const classNames = render().prop('classes') as string[];
 
         expect(classNames.includes('dx-button')).toBe(true);
         expect(classNames.includes('dx-button-has-text')).toBe(false);
@@ -238,13 +244,13 @@ describe('Button', () => {
 
     describe('type', () => {
       it('should use `normal` as a default value', () => {
-        const classNames = render().prop('classes');
+        const classNames = render().prop('classes') as string[];
 
         expect(classNames.includes('dx-button-normal')).toBe(true);
       });
 
       it('should add `dx-button-*` if the type is defined', () => {
-        const classNames = render({ type: 'custom' }).prop('classes');
+        const classNames = render({ type: 'custom' }).prop('classes') as string[];
 
         expect(classNames.includes('dx-button-custom')).toBe(true);
         expect(classNames.includes('dx-button-normal')).toBe(false);
@@ -254,14 +260,15 @@ describe('Button', () => {
     describe('activeStateEnabled', () => {
       it('should be enabled by default', () => {
         const button = render();
+        const classNames = button.prop('classes') as string[];
 
         expect(button.prop('activeStateEnabled')).toBe(true);
-        expect(button.prop('classes').includes('dx-state-active')).toBe(false);
+        expect(classNames.includes('dx-state-active')).toBe(false);
       });
     });
 
     describe('template', () => {
-      const template = ({ text }) => <div className="custom-content">{`${text}123`}</div>;
+      const template = ({ text }): JSXInternal.Element => <div className="custom-content">{`${text}123`}</div>;
 
       it('should render template', () => {
         const button = render({
@@ -325,8 +332,9 @@ describe('Button', () => {
 
       it('should render icon', () => {
         const button = render({ icon: 'test' });
+        const classNames = button.prop('classes') as string[];
 
-        expect(button.prop('classes').includes('dx-button-has-icon')).toBe(true);
+        expect(classNames.includes('dx-button-has-icon')).toBe(true);
         const { source } = button.find(Icon).props();
         expect(source).toEqual('test');
       });
@@ -352,8 +360,9 @@ describe('Button', () => {
           text: 'myButton',
         });
         const elements = button.find('.dx-button-content').children();
+        const classNames = button.prop('classes') as string[];
 
-        expect(button.prop('classes').includes('dx-button-icon-right')).toBe(true);
+        expect(classNames.includes('dx-button-icon-right')).toBe(true);
         expect(elements.at(0).is('.dx-button-text')).toBe(true);
         expect(elements.at(1).is(Icon)).toBe(true);
         expect(elements.at(1).props().position).toEqual('right');
@@ -472,6 +481,7 @@ describe('Button', () => {
             if (keyName === 'space' || which === 'space' || keyName === 'enter' || which === 'enter') {
               customHandler();
               event.cancel = true; // eslint-disable-line no-param-reassign
+
               return event;
             }
 
@@ -614,17 +624,18 @@ describe('Button', () => {
   });
 
   describe('Default option rules', () => {
-    const getDefaultProps = () => {
+    const getDefaultProps = (): ButtonProps => {
       defaultOptions({
         device: () => false,
         options: {},
       });
-      return (Button as any).defaultProps;
+
+      return Button.defaultProps as ButtonProps;
     };
 
     describe('focusStateEnabled', () => {
       it('should be false if device is not desktop', () => {
-        (devices.real as any).mockImplementation(() => ({ deviceType: 'android' }));
+        (devices.real as Mock).mockImplementation(() => ({ deviceType: 'android' }));
         expect(getDefaultProps().focusStateEnabled).toBe(false);
       });
 
@@ -633,6 +644,7 @@ describe('Button', () => {
       });
 
       it('should be false on simulator', () => {
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
         (devices as any).isSimulator.mockImplementation(() => true);
         expect(getDefaultProps().focusStateEnabled).toBe(false);
       });
@@ -640,12 +652,12 @@ describe('Button', () => {
 
     describe('useInkRiple', () => {
       it('should be true if material theme', () => {
-        (themes.current as any).mockImplementation(() => 'material');
+        (themes.current as Mock).mockImplementation(() => 'material');
         expect(getDefaultProps().useInkRipple).toBe(true);
       });
 
       it('should be false if theme is not material', () => {
-        (themes.current as any).mockImplementation(() => 'generic');
+        (themes.current as Mock).mockImplementation(() => 'generic');
         expect(getDefaultProps().useInkRipple).toBe(false);
       });
     });
@@ -653,14 +665,14 @@ describe('Button', () => {
 
   describe('API', () => {
     describe('Focus', () => {
-      it('should call Widget.focus API', () => {
+      it('should call .focus API', () => {
         const apiRef = createRef<ButtonRef>();
         const button = render({ ref: apiRef, focusStateEnabled: true });
-        const { ref: widgetRef } = button.find(Widget).props();
+        const { ref: widgetRef } = button.find(Widget).props() as WidgetProps & { ref };
         const widgetFocusApi = jest.fn();
-        widgetRef.current.focus = widgetFocusApi;
 
-        apiRef.current.focus();
+        (widgetRef as ButtonRef & { current }).current.focus = widgetFocusApi;
+        (apiRef as ButtonRef & { current }).current.focus();
 
         expect(widgetFocusApi).toHaveBeenCalledTimes(1);
       });
@@ -668,7 +680,7 @@ describe('Button', () => {
   });
 
   it('should have dx-button class', () => {
-    const classNames = render().prop('classes');
+    const classNames = render().prop('classes') as string[];
 
     expect(classNames.includes('dx-button')).toBe(true);
   });
diff --git a/testing/jest/error-message.tests.tsx b/testing/jest/error-message.tests.tsx
index 30c9cb230bc6..d160b0d706cc 100644
--- a/testing/jest/error-message.tests.tsx
+++ b/testing/jest/error-message.tests.tsx
@@ -1,9 +1,9 @@
 import { h } from 'preact';
-import { mount } from 'enzyme';
+import { mount, ReactWrapper } from 'enzyme';
 import ErrorMessage from '../../js/renovation/error-message.p';
 
 describe('ErrorMessage', () => {
-  const render = (props = {}) => mount(<ErrorMessage {...props} />).childAt(0);
+  const render = (props = {}): ReactWrapper => mount(<ErrorMessage {...props} />).childAt(0);
 
   describe('Props', () => {
     it('should render `messages` inside the component', () => {
diff --git a/testing/jest/icon.tests.tsx b/testing/jest/icon.tests.tsx
index 49c200ed6603..065f4f33126a 100644
--- a/testing/jest/icon.tests.tsx
+++ b/testing/jest/icon.tests.tsx
@@ -1,9 +1,9 @@
 import { h } from 'preact';
-import { mount } from 'enzyme';
+import { mount, ReactWrapper } from 'enzyme';
 import Icon from '../../js/renovation/icon.p';
 
 describe('Icon', () => {
-  const render = (props = {}) => mount(<Icon {...props} />);
+  const render = (props = {}): ReactWrapper => mount(<Icon {...props} />);
 
   describe('Props', () => {
     describe('source', () => {
diff --git a/testing/jest/utils/events-mock.ts b/testing/jest/utils/events-mock.ts
index 641e4c45d373..6da355d967ea 100644
--- a/testing/jest/utils/events-mock.ts
+++ b/testing/jest/utils/events-mock.ts
@@ -8,7 +8,7 @@ export const KEY = {
   a: 'a',
 };
 
-export const clear = () => {
+export const clear = (): void => {
   eventHandlers = {};
   keyboardHandlers = {};
 };
@@ -28,10 +28,10 @@ export const EVENT = {
 };
 
 export const defaultEvent = {
-  isDefaultPrevented: () => undefined,
-  preventDefault: () => undefined,
-  stopImmediatePropagation: () => undefined,
-  stopPropagation: () => undefined,
+  isDefaultPrevented: (): void => undefined,
+  preventDefault: (): void => undefined,
+  stopImmediatePropagation: (): void => undefined,
+  stopPropagation: (): void => undefined,
   screenX: 5,
   offsetX: 5,
   pageX: 10,
@@ -46,9 +46,9 @@ export const fakeClickEvent = {
   pageY: 0,
 };
 
-export const getEventHandlers = (event) => eventHandlers[event];
+export const getEventHandlers = (event): Array<object> => eventHandlers[event];
 
-export const emitKeyboard = (key, which = key, e = defaultEvent) => {
+export const emitKeyboard = (key, which = key, e = defaultEvent): void => {
   Object.keys(keyboardHandlers).forEach((id) => {
     keyboardHandlers[id].forEach(
       (handler) => handler({ originalEvent: e, keyName: key, which }),
@@ -56,7 +56,7 @@ export const emitKeyboard = (key, which = key, e = defaultEvent) => {
   });
 };
 
-export const emit = (event, e = defaultEvent, element = null) => {
+export const emit = (event, e = defaultEvent, element = null): void => {
     eventHandlers[event]?.forEach(({ handler, el }) => {
       if (!element || el === element) {
         handler(e);
@@ -74,13 +74,15 @@ keyboard.on = (el, focusTarget, handler): string => {
   return keyboardSubscriberId.toString();
 };
 
-keyboard.off = (id) => delete keyboardHandlers[id];
+keyboard.off = (id): boolean => delete keyboardHandlers[id];
 
 jest.mock('../../../js/events/core/events_engine', () => {
   const originalEventsEngine = jest.requireActual('../../../js/events/core/events_engine');
+
   return (
     {
       ...originalEventsEngine,
+
       on: (el, eventName, ...args): void => {
         const event = eventName.split('.')[0];
 
@@ -93,10 +95,12 @@ jest.mock('../../../js/events/core/events_engine', () => {
           el,
         });
       },
+
       off: (_, eventName): void => {
         const event = eventName.split('.')[0];
         eventHandlers[event] = [];
       },
+
       trigger: (element, event): void => {
         emit(EVENT[event], undefined, element);
       },
diff --git a/testing/jest/widget.tests.tsx b/testing/jest/widget.tests.tsx
index 72c0a084dde9..10141bd040c4 100644
--- a/testing/jest/widget.tests.tsx
+++ b/testing/jest/widget.tests.tsx
@@ -1,14 +1,15 @@
 import { h, createRef } from 'preact';
-import { mount, shallow } from 'enzyme';
 // Should be before component import
+import { mount, shallow, ShallowWrapper } from 'enzyme';
 import {
   clear as clearEventHandlers, defaultEvent, emit, getEventHandlers, fakeClickEvent, EVENT,
 } from './utils/events-mock';
 import Widget from '../../js/renovation/widget.p';
 import type { WidgetRef } from '../../js/renovation/widget.p';
+import type { WidgetProps } from '../../js/renovation/widget';
 
 describe('Widget', () => {
-  const render = (props = {}) => shallow(<Widget {...props} />);
+  const render = (props = {}): ShallowWrapper => shallow(<Widget {...props} />);
 
   beforeEach(clearEventHandlers);
 
@@ -16,20 +17,23 @@ describe('Widget', () => {
     describe('accessKey', () => {
       it('should render `accesskey` attribute', () => {
         const widget = render({ accessKey: 'y', focusStateEnabled: true });
+        const props = widget.props() as WidgetProps;
 
-        expect(widget.props().accessKey).toBe('y');
+        expect(props.accessKey).toBe('y');
       });
 
       it('should not render if disabled', () => {
         const widget = render({ accessKey: 'y', focusStateEnabled: true, disabled: true });
+        const props = widget.props() as WidgetProps;
 
-        expect(widget.props().accessKey).toBe(undefined);
+        expect(props.accessKey).toBe(undefined);
       });
 
       it('should not render if `focusStateEnabled` is false', () => {
         const widget = render({ accessKey: 'y', focusStateEnabled: false });
+        const props = widget.props() as WidgetProps;
 
-        expect(widget.props().accessKey).toBe(undefined);
+        expect(props.accessKey).toBe(undefined);
       });
 
       it('should take a focus if the `accessKey` is pressed', () => {
@@ -82,26 +86,30 @@ describe('Widget', () => {
     describe('width/height', () => {
       it('should have the ability to be a function', () => {
         const widget = render({ width: () => 50, height: () => 'auto' });
+        const props = widget.props() as WidgetProps;
 
-        expect(widget.props().style).toEqual({ width: 50, height: 'auto' });
+        expect(props.style).toEqual({ width: 50, height: 'auto' });
       });
 
       it('should process string values', () => {
         const widget = render({ width: '50px', height: () => '100%' });
+        const props = widget.props() as WidgetProps;
 
-        expect(widget.props().style).toEqual({ width: '50px', height: '100%' });
+        expect(props.style).toEqual({ width: '50px', height: '100%' });
       });
 
       it('should process number values', () => {
         const widget = render({ width: 50, height: 70 });
+        const props = widget.props() as WidgetProps;
 
-        expect(widget.props().style).toEqual({ width: 50, height: 70 });
+        expect(props.style).toEqual({ width: 50, height: 70 });
       });
 
       it('should ignore null/undefined values', () => {
         const widget = render({ width: null, height: undefined });
+        const props = widget.props() as WidgetProps;
 
-        expect(widget.props().style).toEqual({});
+        expect(props.style).toEqual({});
       });
     });
 
@@ -190,8 +198,9 @@ describe('Widget', () => {
     describe('activeStateEnabled', () => {
       it('should be disabled by default', () => {
         const widget = render();
+        const props = widget.instance().props as WidgetProps;
 
-        expect(widget.instance().props.activeStateEnabled).toBe(false);
+        expect(props.activeStateEnabled).toBe(false);
         expect(widget.hasClass('dx-state-active')).toBe(false);
       });
     });
@@ -199,8 +208,9 @@ describe('Widget', () => {
     describe('hoverStateEnabled', () => {
       it('should be disabled by default', () => {
         const widget = render();
+        const props = widget.instance().props as WidgetProps;
 
-        expect(widget.instance().props.hoverStateEnabled).toBe(false);
+        expect(props.hoverStateEnabled).toBe(false);
         expect(widget.hasClass('dx-state-hover')).toBe(false);
       });
     });
@@ -208,8 +218,9 @@ describe('Widget', () => {
     describe('focusStateEnabled', () => {
       it('should be disabled by default', () => {
         const widget = render();
+        const props = widget.instance().props as WidgetProps;
 
-        expect(widget.instance().props.focusStateEnabled).toBe(false);
+        expect(props.focusStateEnabled).toBe(false);
         expect(widget.hasClass('dx-state-focus')).toBe(false);
       });
     });
@@ -450,7 +461,7 @@ describe('Widget', () => {
   describe('Events', () => {
     describe('onClick', () => {
       it('should detach `dxclick` event before rerendering', () => {
-        const widget = mount(<Widget onClick={() => undefined} />);
+        const widget = mount(<Widget onClick={(): void => undefined} />);
 
         expect(getEventHandlers(EVENT.dxClick).length).toBe(1);
         widget.unmount();
@@ -469,7 +480,7 @@ describe('Widget', () => {
 
     describe('onDimensionChanged', () => {
       it('should detach `dxresize` event before rerendering', () => {
-        const widget = mount(<Widget onDimensionChanged={() => undefined} />);
+        const widget = mount(<Widget onDimensionChanged={(): void => undefined} />);
 
         expect(getEventHandlers(EVENT.resize).length).toBe(1);
         widget.unmount();
@@ -495,7 +506,7 @@ describe('Widget', () => {
       });
 
       it('should detach `dxshown` and `dxhiding` events before rerendering', () => {
-        const widget = mount(<Widget onVisibilityChange={() => undefined} />);
+        const widget = mount(<Widget onVisibilityChange={(): void => undefined} />);
 
         expect(getEventHandlers(EVENT.shown).length).toBe(1);
         expect(getEventHandlers(EVENT.hiding).length).toBe(1);