changes.patch

diff --git a/.node-version b/.node-version
new file mode 100644
index 0000000..62df50f
--- /dev/null
+++ b/.node-version
@@ -0,0 +1 @@
+14.17.0
diff --git a/__tests__/components/common/query_param.test.js b/__tests__/components/common/query_param.test.js
new file mode 100644
index 0000000..0781047
--- /dev/null
+++ b/__tests__/components/common/query_param.test.js
@@ -0,0 +1,18 @@
+import * as queryParamModule from "../../../components/common/query_param";
+
+describe('query param function test', () => {
+    test('returns query param from the url', async () => {
+        let result = queryParamModule.getParameterByName('testQuery', 'http://www.example.com/some_page?testQuery=testValue')
+        expect(result).toBe('testValue');
+    })
+
+    test('returns empty string from the url when query param is present', async () => {
+        let result = queryParamModule.getParameterByName('testQuery', 'http://www.example.com/some_page?testQuery')
+        expect(result).toBe('');
+    })
+
+    test('returns null when url does not contain the query param', async () => {
+        let result = queryParamModule.getParameterByName('testQuery', 'http://www.example.com/some_page')
+        expect(result).toBeNull();
+    })
+})
\ No newline at end of file
diff --git a/__tests__/pages/customers/list_page.test.js b/__tests__/pages/customers/list_page.test.js
index efe3f47..84ecef4 100644
--- a/__tests__/pages/customers/list_page.test.js
+++ b/__tests__/pages/customers/list_page.test.js
@@ -3,28 +3,28 @@ import { render, screen, fireEvent, waitFor } from '@testing-library/react'
 import { server } from '../../server'
 import { createMockRouter } from "../../mock_router";
 import { rest } from 'msw'
+import * as queryParamModule from "../../../components/common/query_param"
 
 import { CustomersListPage } from "../../../pages/customers/list";
 
 describe('CustomersListPage Component test', () => {
-    const { location } = window;
-
     beforeEach(() => {
-        delete window.location;
-        window.location = {
-            href: 'https://www.example.com',
-        };
+        jest.clearAllMocks();
+        queryParamModule.getParameterByName = jest.fn();
     });
 
     afterEach(() => {
-        window.location = location;
+        jest.clearAllMocks();
     });
 
     test('prefilling firstName search from query param', async () => {
-
-        window.location = {
-            href: 'https://www.example.com?firstName=test-first-name',
-        };
+        queryParamModule.getParameterByName.mockImplementation((param) => {
+            if(param == 'firstName') {
+                return 'test-first-name';
+            } else {
+                throw new Error("Unexpected param: " + param);
+            }
+        });
 
         server.use(
             rest.get(process.env.NEXT_PUBLIC_CUSTOMER_API_BASE_URL + "/customers", (req, res, ctx) => {
@@ -41,9 +41,13 @@ describe('CustomersListPage Component test', () => {
     });
 
     test('display customers filtered by first name from query', async () => {
-        window.location = {
-            href: 'https://www.example.com?firstName=test-first-name',
-        };
+        queryParamModule.getParameterByName.mockImplementation((param) => {
+            if(param == 'firstName') {
+                return 'test-first-name';
+            } else {
+                throw new Error("Unexpected param: " + param);
+            }
+        });
 
         var receivedFirstName = null;
         server.use(
@@ -125,15 +129,7 @@ describe('CustomersListPage Component test', () => {
         );
 
         const mockRouter = createMockRouter()
-        let receivedUrl = null;
-        let receivedAs = null;
-        let receivedOptions = null;
-        mockRouter.push = function (url, as, options) {
-            receivedUrl = url;
-            receivedAs = as;
-            receivedOptions = options;
-            return;
-        }
+        mockRouter.push = jest.fn()
         mockRouter.pathname = 'test-path-name';
         mockRouter.query = {
             firstName: 'test-old-first-name',
@@ -156,11 +152,12 @@ describe('CustomersListPage Component test', () => {
         await waitFor(() => expect(callCount).toBe(2));
         await waitFor(() => expect(receivedFirstName).toBe('test-first-name'));
 
-        expect(receivedUrl.pathname).toBe("test-path-name");
-        expect(receivedUrl.query.firstName).toBe("test-first-name");
-        expect(receivedUrl.query.someOtherQuery).toBe("test-query");
-        expect(receivedAs).toBeUndefined();
-        expect(receivedOptions.shallow).toBe(true);
+        expect(mockRouter.push.mock.calls.length).toBe(1);
+        expect(mockRouter.push.mock.calls[0][0].pathname).toBe("test-path-name");
+        expect(mockRouter.push.mock.calls[0][0].query.firstName).toBe("test-first-name");
+        expect(mockRouter.push.mock.calls[0][0].query.someOtherQuery).toBe("test-query");
+        expect(mockRouter.push.mock.calls[0][1]).toBeUndefined();
+        expect(mockRouter.push.mock.calls[0][2].shallow).toBe(true);
     })
 
     test('does not filter customers by first name given empty input and removes first name from query', async () => {
@@ -180,15 +177,7 @@ describe('CustomersListPage Component test', () => {
         );
 
         const mockRouter = createMockRouter()
-        let receivedUrl = null;
-        let receivedAs = null;
-        let receivedOptions = null;
-        mockRouter.push = function (url, as, options) {
-            receivedUrl = url;
-            receivedAs = as;
-            receivedOptions = options;
-            return;
-        }
+        mockRouter.push = jest.fn()
         mockRouter.pathname = 'test-path-name';
         mockRouter.query = {
             firstName: 'test-old-first-name',
@@ -211,11 +200,12 @@ describe('CustomersListPage Component test', () => {
         await waitFor(() => expect(callCount).toBe(2));
         await waitFor(() => expect(receivedFirstName).toBeNull());
 
-        expect(receivedUrl.pathname).toBe("test-path-name");
-        expect(receivedUrl.query.firstName).toBeUndefined();
-        expect(receivedUrl.query.someOtherQuery).toBe("test-query");
-        expect(receivedAs).toBeUndefined();
-        expect(receivedOptions.shallow).toBe(true);
+        expect(mockRouter.push.mock.calls.length).toBe(1);
+        expect(mockRouter.push.mock.calls[0][0].pathname).toBe("test-path-name");
+        expect(mockRouter.push.mock.calls[0][0].query.firstName).toBeUndefined();
+        expect(mockRouter.push.mock.calls[0][0].query.someOtherQuery).toBe("test-query");
+        expect(mockRouter.push.mock.calls[0][1]).toBeUndefined();
+        expect(mockRouter.push.mock.calls[0][2].shallow).toBe(true);
     })
 
     test('displays empty customers', async () => {
diff --git a/__tests__/pages/customers/new_page.test.js b/__tests__/pages/customers/new_page.test.js
index 2cf5ff8..cbb067d 100644
--- a/__tests__/pages/customers/new_page.test.js
+++ b/__tests__/pages/customers/new_page.test.js
@@ -8,6 +8,7 @@ import { NewCustomerPage } from "../../../pages/customers/new";
 
 describe('NewCustomerPage Component test', () => {
     beforeEach(() => {
+        jest.clearAllMocks();
         server.use(
             rest.post(process.env.NEXT_PUBLIC_CUSTOMER_API_BASE_URL + "/customers", (req, res, ctx) => {
                 return res(
@@ -17,14 +18,12 @@ describe('NewCustomerPage Component test', () => {
         );
     });
 
+    afterEach(() => {
+        jest.clearAllMocks();
+    });
+
     test('navigation links', async () => {
-        var redirectUrl = null;
-        const mockRouter = createMockRouter()
-        mockRouter.push = function(url, as, options) {
-            redirectUrl = url;
-            return;
-        }
-        render(<NewCustomerPage router={mockRouter} />);
+        render(<NewCustomerPage router={createMockRouter()} />);
         expect(screen.queryByTestId('home-link').getAttribute("href")).toBe('/');
         expect(screen.queryByTestId('list-customers-link').getAttribute("href")).toBe('/customers/list');
         expect(screen.queryByTestId('cancel-button').getAttribute("href")).toBe('/customers/list');
@@ -43,12 +42,8 @@ describe('NewCustomerPage Component test', () => {
             }),
         );
 
-        var redirectUrl = null;
         const mockRouter = createMockRouter()
-        mockRouter.push = function(url, as, options) {
-            redirectUrl = url;
-            return;
-        }
+        mockRouter.push = jest.fn()
         render(<NewCustomerPage router={mockRouter} />);
         expect(screen.queryByTestId('first-name').getAttribute("value")).toBe('');
         expect(screen.queryByTestId('last-name').getAttribute("value")).toBe('');
@@ -60,7 +55,8 @@ describe('NewCustomerPage Component test', () => {
         expect(screen.queryByTestId('submitting-content')).not.toBeNull();
         await waitFor(() => expect(screen.queryByTestId('submitting-content')).toBeNull());
 
-        await waitFor(() => expect(redirectUrl).toBe('/customers/list/'));
+        await waitFor(() => expect(mockRouter.push.mock.calls.length).toBe(1));
+        await waitFor(() => expect(mockRouter.push.mock.calls[0][0]).toBe('/customers/list/'));
 
         await waitFor(() => expect(requestJson).not.toBeNull());
         expect(requestJson.firstName).toBe('test-first-name');