Understanding Flaky Tests and Element Not Found Errors in Cypress

Cypress runs in a real browser, but asynchronous UI changes, network delays, and DOM re-renders can cause tests to intermittently fail due to elements not being available when expected.

Common Causes of Flaky Cypress Tests

• UI re-rendering delays: Elements load dynamically and are unavailable when Cypress queries the DOM.
• Assertions running too early: Cypress executes assertions before the UI has settled.
• Incorrect use of retries: Tests fail when elements are not awaited properly.
• Network request variability: API calls return at different times, affecting test consistency.

Diagnosing Flaky Cypress Test Failures

Checking Cypress Command Logs

Use the Cypress Test Runner to inspect command execution:

cy.get(".element-selector").should("be.visible");

Verifying Network Response Timing

Use cy.intercept to log API responses:

cy.intercept("GET", "/api/data").as("getData");
cy.wait("@getData").then((interception) => {
  console.log(interception.response.body);
});

Detecting Unstable DOM Changes

Check if the element exists before performing actions:

cy.get(".element-selector", { timeout: 10000 }).should("exist");

Fixing Flaky Cypress Tests

Ensuring Proper Element Visibility

Wait for elements to be visible before interacting:

cy.get(".element-selector").should("be.visible").click();

Using Cypress Retries for Dynamic Content

Wrap assertions inside a retry block:

cy.get(".element-selector").should(($el) => {
  expect($el).to.have.length.greaterThan(0);
});

Stabilizing Network Requests

Ensure API responses are fully loaded before proceeding:

cy.wait("@getData").its("response.statusCode").should("eq", 200);

Handling Flaky UI Transitions

Use explicit waits for animations or page loads:

cy.wait(500);

Preventing Future Flaky Tests

• Use cy.wait for network requests instead of arbitrary timeouts.
• Leverage Cypress retries for dynamic elements.
• Avoid hardcoded waits; use conditional assertions instead.

Conclusion

Flaky tests in Cypress occur due to timing issues, dynamic UI updates, and unstable network requests. By using proper retries, waiting for elements dynamically, and stabilizing network interactions, developers can ensure consistent test execution.

FAQs

1. Why does Cypress fail to find elements intermittently?

The DOM might be updating dynamically, causing elements to be missing when Cypress queries them.

2. How can I fix network-dependent flaky tests?

Use cy.intercept and cy.wait to ensure API responses are ready before proceeding.

3. Should I use cy.wait with fixed time values?

No, use conditional assertions instead to wait for elements dynamically.

4. How do I make Cypress tests more reliable?

Use proper chaining, ensure elements are visible before interaction, and stabilize network requests.

5. Can I retry failed assertions automatically?

Yes, Cypress automatically retries assertions within commands like should() and get().