test: add extra unit test for invalid login

Author: jescalada

cypress/e2e/login.cy.js

@@ -31,6 +31,16 @@ describe('Login page', () => {
     cy.url().should('include', '/dashboard/repo');
   })
 
+  it('should show an error snackbar on invalid login', () => {
+    cy.get('[data-test="username"]').type('wronguser');
+    cy.get('[data-test="password"]').type('wrongpass');
+    cy.get('[data-test="login"]').click();
+
+    cy.get('.MuiSnackbarContent-message')
+      .should('be.visible')
+      .and('contain', 'You entered an invalid username or password...');
+  });
+
   describe('OIDC login button', () => {
     it('should exist', () => {
       cy.get('[data-test="oidc-login"]').should('exist');