fix(auth): correctly redirect the user to the last visited page after login

Resolves https://kolaente.dev/vikunja/frontend/issues/3682

cypress/e2e/user/login.spec.ts

@@ -1,4 +1,5 @@
 import {UserFactory} from '../../factories/user'
+import {ProjectFactory} from '../../factories/project'
 
 const testAndAssertFailed = fixture => {
 	cy.intercept(Cypress.env('API_URL') + '/login*').as('login')
@@ -13,26 +14,28 @@ const testAndAssertFailed = fixture => {
 	cy.get('div.message.danger').contains('Wrong username or password.')
 }
 
-const username = 'test'
+const credentials = {
+	username: 'test',
+	password: '1234',
+}
+
+function login() {
+	cy.get('input[id=username]').type(credentials.username)
+	cy.get('input[id=password]').type(credentials.password)
+	cy.get('.button').contains('Login').click()
+	cy.url().should('include', '/')
+}
 
 context('Login', () => {
 	beforeEach(() => {
-		UserFactory.create(1, {username})
+		UserFactory.create(1, {username: credentials.username})
 	})
 
 	it('Should log in with the right credentials', () => {
-		const fixture = {
-			username: 'test',
-			password: '1234',
-		}
-
 		cy.visit('/login')
-		cy.get('input[id=username]').type(fixture.username)
-		cy.get('input[id=password]').type(fixture.password)
-		cy.get('.button').contains('Login').click()
-		cy.url().should('include', '/')
+		login()
 		cy.clock(1625656161057) // 13:00
-		cy.get('h2').should('contain', `Hi ${fixture.username}!`)
+		cy.get('h2').should('contain', `Hi ${credentials.username}!`)
 	})
 
 	it('Should fail with a bad password', () => {
@@ -57,4 +60,15 @@ context('Login', () => {
 		cy.visit('/')
 		cy.url().should('include', '/login')
 	})
+	
+	it('Should redirect to the previous route after logging in', () => {
+		const projects = ProjectFactory.create(1)
+		cy.visit(`/projects/${projects[0].id}/list`)
+
+		cy.url().should('include', '/login')
+		
+		login()
+
+		cy.url().should('include', `/projects/${projects[0].id}/list`)
+	})
 })