Using Data to Build Dynamic Tests

In the lesson Database Initialization & Seeding, we give you several strategies for creating the data necessary for your tests. In this lesson, we will help you better understand how to use that data to drive your tests.

What are Data-Driven Tests?

When we speak of "Data-Driven Tests," we refer to using variables, fixtures, or data from a database to construct all aspects of a dynamic test (UI interactions, expectations, and the test itself).

For example, let's say you have a test which tests the login form in your app. You could hard code the data, like so:

cy.get("username").type("jdoe")
cy.get("password").type("password123")

Or you could use data from variables.

const users = [
  {
    username: "John",
    password: "password123",
  },
  {
    username: "Jane",
    password: "password123",
  },
]

cy.get("username").type(users[0].username)
cy.get("password").type(users[0].password)

You could also use data from a fixture.

cy.fixture("users.json").as("usersData")

cy.get("username").type(usersData[0].username)
cy.get("password").type(usersData[0].password)

Or, you could use an actual user from your database.

Using data from remote systems (API, database, etc.) to drive seed data and tests

describe("Notifications", () => {
  const ctx = {}

  beforeEach(() => {
    // ...

    cy.database("filter", "users").then((users) => {
      ctx.userA = users[0]
      ctx.userB = users[1]
      ctx.userC = users[2]
    })
  })

  it("allows users to login", () => {
    cy.get("username").type(ctx.userA.userName)
    cy.get("password").type(ctx.userA.password)
  })
})

In this example, cy.database() is a custom Cypress command which performs operations on our database depending upon which arguments are passed into it. You can learn how this command works here.

Benefits of Data-Driven Tests

Using actual data has several benefits. First, you are using existing data from your application. This more closely mimics how real users interact with your app. Hard-coded data can be challenging to maintain over time, as it requires consistent updating and maintenance. Instead of hard-coded data, the only thing you have to maintain is the data itself.

Wrap Up

Congrats! You have finished the fourth course of Real World Testing with Cypress. If you have completed all four courses, make sure to check out the Real World Examples as they demonstrate real-world usage of Cypress testing methods, patterns, and workflows.