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Overview

Make AI-powered assertions about the current screen state using natural language. The AI analyzes the screen and verifies that your assertion is true.

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Syntax

await testdriver.assert(assertion)

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Parameters

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assertion
string
required
Natural language description of what should be true

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Returns

Promise<boolean> - true if assertion passes, throws error if assertion fails

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Examples

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Basic Assertions

// Verify page elements
await testdriver.assert('the login page is displayed');
await testdriver.assert('submit button is visible');
await testdriver.assert('error message is shown');

// Verify text content
await testdriver.assert('the page title is "Welcome"');
await testdriver.assert('username field contains "john.doe"');
await testdriver.assert('success message says "Account created"');

// Verify states
await testdriver.assert('the form is empty');
await testdriver.assert('the checkbox is checked');
await testdriver.assert('the dropdown shows "United States"');

// Verify visual appearance
await testdriver.assert('the button is blue');
await testdriver.assert('the loading spinner is displayed');
await testdriver.assert('the modal dialog is open');

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Best Practices

Be specific in assertionsMore specific assertions are more reliable:
// ❌ Too vague
await testdriver.assert('button is visible');

// ✅ Specific
await testdriver.assert('blue submit button is visible below the form');
Assert state changesVerify state before and after actions:
// Before
await testdriver.assert('cart is empty');

// Action
const addBtn = await testdriver.find('add to cart');
await addBtn.click();

// After
await testdriver.assert('cart contains 1 item');
Use with test framework assertionsCombine AI assertions with traditional test assertions:
// AI assertion
const result = await testdriver.assert('success message is displayed');

// Framework assertion
expect(result).toBeTruthy();

// Extract for detailed comparison
const message = await testdriver.remember('the success message text');
expect(message).toContain('successfully');

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Polling Assertions

For conditions that may take time to become true: 
async function waitForAssertion(testdriver, assertion, timeout = 30000) {
  const startTime = Date.now();
  
  while (Date.now() - startTime < timeout) {
    try {
      await testdriver.assert(assertion);
      return true; // Assertion passed
    } catch (error) {
      // Assertion failed, wait and retry
      await new Promise(r => setTimeout(r, 1000));
    }
  }
  
  throw new Error(`Assertion timeout: "${assertion}"`);
}

// Usage
await waitForAssertion(testdriver, 'page has finished loading', 30000);
await waitForAssertion(testdriver, 'results are displayed', 10000);

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Use Cases

// Try to submit empty form
const submitBtn = await testdriver.find('submit button');
await submitBtn.click();

// Verify validation errors
await testdriver.assert('email field shows "required" error');
await testdriver.assert('password field shows "required" error');

// Verify form not submitted
await testdriver.assert('still on the form page');

const loginBtn = await testdriver.find('login button');
await loginBtn.click();

// Verify navigation
await testdriver.assert('user dashboard is displayed');
await testdriver.assert('welcome message shows user name');
await testdriver.assert('logout button is visible');

const loadBtn = await testdriver.find('load more button');
await loadBtn.click();

// Poll for content using helper
await waitForAssertion(testdriver, 'more than 10 items are shown', 10000);
await testdriver.assert('load more button is still visible');

// Verify hover effect
const button = await testdriver.find('primary button');
await button.hover();

await testdriver.assert('button background is darker');

// Verify button is enabled
await testdriver.assert('submit button is enabled');

// Step 1
await testdriver.assert('step 1 is active');
const nextBtn = await testdriver.find('next button');
await nextBtn.click();

// Step 2
await testdriver.assert('step 2 is active');
await testdriver.assert('step 1 is completed');
await nextBtn.click();

// Step 3
await testdriver.assert('step 3 is active');
await testdriver.assert('step 2 is completed');

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Complete Example

import { beforeAll, afterAll, describe, it, expect } from 'vitest';
import TestDriver from 'testdriverai';

describe('Assertions', () => {
  let testdriver;

  beforeAll(async () => {
    client = new TestDriver(process.env.TD_API_KEY);
    await testdriver.auth();
    await testdriver.connect({ newSandbox: true });
  });

  afterAll(async () => {
    await testdriver.disconnect();
  });

  it('should validate login flow', async () => {
    await testdriver.focusApplication('Google Chrome');
    
    // Verify initial state
    await testdriver.assert('the login page is displayed');
    await testdriver.assert('username field is empty');
    await testdriver.assert('password field is empty');
    
    // Fill form
    const usernameField = await testdriver.find('username input');
    await usernameField.click();
    await testdriver.type('testuser');
    
    await testdriver.pressKeys(['tab']);
    await testdriver.type('password123');
    
    // Verify fields filled
    await testdriver.assert('username field contains "testuser"');
    await testdriver.assert('password field is not empty');
    
    // Submit
    await testdriver.pressKeys(['enter']);
    
    // Poll for success
    await waitForAssertion(testdriver, 'user dashboard is displayed', 10000);
    
    // Verify logged in state
    await testdriver.assert('welcome message is shown');
    await testdriver.assert('logout button is visible');
    
    // Verify login page is gone
    await testdriver.assert('login form is displayed', false, true);
  });

  it('should show validation errors', async () => {
    // Try empty submission
    const submitBtn = await testdriver.find('submit button');
    await submitBtn.click();
    
    // Verify multiple errors
    const errors = [
      'email field shows error',
      'name field shows error',
      'password field shows error'
    ];
    
    for (const error of errors) {
      const result = await testdriver.assert(error);
      expect(result).toBeTruthy();
    }
    
    // Verify not submitted
    await testdriver.assert('confirmation page is shown', false, true);
  });
});
  • remember() - Extract information for detailed assertions
  • find() - Locate elements to verify
  • ai() - Complex AI-driven tasks