Over my 10+ years working on test automation projects, there is one task that still keeps developers and testers awake at night – testing complex enterprise email functionality.
As someone that has set up end-to-end test suites across nearly 4000 desktop and mobile browsers, I can certainly appreciate these challenges. Email workflows tend to cut across various systems, require stubbing out external services, handle dynamic content etc. Getting email testing right is the difference between seamless experiences for your users vs thousands of angry emails flooding your inboxes.
The good news is – with the right design, tooling and debugging practices – you can prevent email issues from ever reaching your users in the first place!
This comprehensive guide aims to provide everything you need to know to start testing emails reliably using Cypress.
Why Email Testing Matters More Than Ever
Let‘s first understand why testing email capabilities within web and mobile apps matters more today than ever before:
Email functionality is increasingly critical – Whether it is transactional mail, marketing campaigns or notifications – the email channel has become the preferred way of reaching customers for businesses. Clearly, any issues with email deliverability or rendering can significantly impact revenue and customer trust.
Users have zero tolerance for failures – With consumer attention spans averaging just 8 seconds, even minor email glitches can result in losing a customer forever. 74% users report email rendering issues as a reason for unsubscribing.
Fragmented landscape – Between Outlook, Gmail, Yahoo and countless other clients – not to mention different mobile app versions – delivering a flawless email experience across the board has become exceptionally hard.
Big costs of small mistakes – A single bad email deployment can destroy years of carefully built sender reputation. Recovering from blocklists and spam folders averages $200K+ in dev effort and revenue impact.
Testing is still largely manual – Despite the risks, email testing is still done manually, often relying on flawed staged test environments causing production email failures.
Key Capabilities in an Email Testing Framework
Based on helping fix email testing gaps across many organizations, I‘ve compiled below the must-have capabilities:
Having accelerated feedback loops is important so bugs can be fixed before the next major deployment. Visual testing catches subjective styling issues missed by code analysis.
And of course completely automating aspects like scheduling, reporting, Wake ups and alerting are key to reducing maintenance costs.
As we will see, Cypress meets and exceeds these requirements for reliable and maintainable email testing.
Overview of Testing Emails with Cypress
Cypress is an end-to-end test runner that lets you execute automated tests that run directly inside the real browser. Here is how Cypress makes email testing remarkably simple:
Runs in-browser like users – Tests actually execute consuming real resources giving you confidence that emails will render correctly for users
Time travel debugging – Cypress records videos of test runs which lets you "go back in time" to understand failures
Auto retries and waits – Flaky tests are automatically retried. Assertions automatically wait for expected conditions preventing false positives
Spies and mocks – Enables seamlessly stubbing out external services like SMTP servers
Custom tasks and commands – Interact directly with your email APIs and services right within tests
Dashboard and CI integrations – Visibility into test metrics, scheduling integration runs etc out of the box
Combine these with the capabilities standard in any programming language – object comparison, CSS selector queries etc – and you have a very powerful toolkit for testing emails reliably.
it("confirms signup with welcome email", () => {
cy.visit("/signup");
cy.get(‘#email‘).type(‘[email protected]‘)
cy.get("form").submit();
cy.task(‘getNewEmail‘).then(email => {
expect(email.subject).to.eq(‘Welcome!‘)
expect(email.body).to.include(‘Greetings tester‘)
})
})This test combines multiple Cypress capabilities:
cy.visit()– application routingcy.get().type()– interact with UI- Custom
getNewEmail()task – email server integration - Assertions on dynamic email content
Real World Email Functionality to Test
Now that we understand Cypress‘ capabilities, let‘s explore common scenarios you will need to test related to email:
Transactional Mail
Welcome emails, receipts, password resets etc. Visual consistency and accurate personalization are key.
Marketing Mail
High volume batches sent periodically. Ensure deliverability and measure engagement.
Notifications and Alerts
Immediate situational messages like order failures. Verify delivery even during large bursts.
User Re-engagement
Win back disengaged users via personalized campaigns. Confirm re-activations.
Third Party Integration
RO bust, abuse complaints etc. Mimic how ESPs classify mail originating from your app.
Visual Consistency
Prevent subjective styling regressions across email templates. Measure rendering correctness.
Step-by-Step Guide to Test Emails with Cypress
Now that we understand what to test, let’s go step-by-step into how to test emails with Cypress:
Step 1: Install Cypress and Configure Plugins
Make sure Node is installed, and install Cypress locally or globally:
$ npm install cypress --save-devCypress integrations are configured in the plugins file cypress/plugins/index.js.
Let’s add nodemailer to connect to a test SMTP server:
const nodemailer = require("nodemailer");
module.exports = (on, config) => {
const transport = nodemailer.createTransport(
host: "mail.ethereal.email",
port: 587,
auth: {
user: "your-username",
pass: "your-password"
}
);
on("task", {
async sendTestEmail({ to, subject, html }) {
const result = await transport.sendMail({
from: "[email protected]",
to,
subject,
html
});
return result;
}
});
}This creates an Ethereal account and SMTP connection for sending test emails later.
Step 2: Write Test Cases for Email Scenarios
Let‘s start with a simple example – sending a welcome email:
it("sends welcome email after signup", () => {
const email = `test-${new Date().getTime()}@email.com`
cy.visit("/signup");
cy.get(‘#email‘).type(email);
cy.contains(‘button‘, ‘Create Account‘).click();
cy.task(‘sendTestEmail‘, {
to: email,
subject: ‘Welcome!‘,
html: `<p>Thanks for joining!</p>`
}).then(response => {
expect(response.accepted[0]).to.equal(email)
});
});We:
- Sign up a user
- Call
sendTestEmailtask with email details - Assert Cypress command response
Let’s try a more advanced example – testing a password reset email:
it("sends password reset email", () => {
const email = `test-${new Date().getTime()}@email.com`
cy.requestPasswordReset(email);
cy.task(‘getInboxUnreadEmail‘, email).then(message => {
expect(message.subject).to.equal("Reset your password");
expect(message.body).to.include("To initiate reset");
})
}) Here we:
- Reset password for a test email
- Fetch the latest unread email received
- Assert subject and contents
We can build on these patterns to test complex scenarios involving multiple applications, asynchronous timed emails etc.
Step 3: Best Practices for Effective Email Tests
Through years of hands-on experience helping large companies fix their email testing, I‘ve compiled a list of practical recommendations worth following:
Use real accounts and inboxes – Dummy inboxes don‘t reflect actual email sending infra and delays. For example, use services like Mailosaur and Mailslurp that provide test email accounts with APIs. This helps uncover gaps between staging and production environments.
Test across client applications – Emails may render perfectly on Gmail Web but have broken styling in Outlook Desktop. Invest in browser test clouds like BrowserStack to confirm email compatibility across client apps.
Automate visual testing – Flaky CSS can lead to emails displaying correctly in tests but rendering badly for users. Use tools like Applitools, Percy, Screenster etc to prevent visual regressions across clients.
Take failure screenshots – Unexpected test failures will happen. Automate screenshot and HTML saving on failures to enable debugging without having to reproduce issues.
Isolate test data – Shared test data leads to hard-to-spot side effects. Provision a separate database for running test email jobs exclusively used by test suites.
Mock external services – To prevent external services impacting test reliability & speed, ensure ORM mock adapters and test doubles are implemented.
Follow CI/CD best practices – At minimum, email tests should run on every commit and PR to the main code branch. Consider running visual smoke tests on every component deployment.
Track email metrics – Analyze email send volume data, quotas exceeded, complaint rates etc during tests to gain insight into production usage and capacity planning.
Use generated email addresses – Static test email addresses may get throttled skewing test results. Create random addresses for each test case.
Schedule recurring runs – Schedule test suites to run at intervals mimicking real usage patterns. Continuously confirm at scale.
Debugging Failing Email Tests with Cypress
Despite best practices, you will inevitably encounter failing email tests. Based on past experience troubleshooting, here are my top debugging tips:
1. Inspect the Network Panel
Check all requests made to SMTP, IMAP servers for failures and inspect response payloads. This can reveal issues like authentication errors, throttling limits etc.
2. Log and assert interim states
Insert additional test assertions between steps to isolate failures, not just at the end.
3. Check server app logs
Application logs from API servers often contain additional context on errors not available from Cypress alone.
4. Use unique identifiers
Include unique strings like email IDs in dynamic content to simplify searching logs to isolate failures.
5. Visualize and video record
Leverage automatically recorded screenshots and videos from failed runs rather than solely relying on logs. The visual state is invaluable in diagnosing issues.
6. Mock/simulate edge scenarios
Recreate complex scenarios like server downtimes, queued deliveries and how your system should handle them.
7. Integrate with external monitoring
Sync Cypress test runs with uptime monitors, performance trackers etc for additional signals. Tests may pass but the workflow still fails.
8. Analyze email server bounced and engagments
Email tracking pixels reveal details beyond test pass/fails like unsubscribe rates, spam complaints etc. Great way to validate production readiness.
9. Parameterize and permutation tests
Vary test data across domains, geographies, email sizes etc to uncover edge case failures.
10. Check spam trap inboxes
Set up inbox accounts specifically to receive spam marked mails. Tests can pass while users still experience deliverability issues.
With these troubleshooting steps, you can tackle everything from intermittent test failures, dynamic data issues to problems only experienced by real users in production.
Sample Test Reports from Cypress Dashboard
Cypress Dashboard offers insightful reports that help communicate the risk and stability of critical email workflows.
Here are examples of test metrics available out of the box:
Visualized Test Statuses
The overall test suite pass rates helps spot reliability issues with email tests:
Email Test Run Quality Over Time
Are tests getting slower and more flaky? Dashboard charts visualize health metrics across builds:
Historic Test Run Screenshots
When tests fail, corresponding run screenshots are available link to debug:
CI/CD Integration
Centralized tracking and alerting of test failures across different environments:
These help communicate risk factors of email workflow changes to leadership before impacting customers.
Key Takeaways
If you remember nothing else from this guide, do internalize and follow these core recommendations:
Adopt Cypress – For reliable email testing, Cypress combined with real accounts, visual sanity checks is a proven high return combination.
Prioritize interfaces and destructive actions first – Reset passwords, failed payment alerts – test notifications that can significantly impact user trust and retention.
Prevent subjective visual regressions – Be extra cautious when changing templates and embedded CSS. Things like mobile styling breaks and color contrast changes can appear minor in tests but drastically alter user experiences.
Tie tests to deployment sign off – Without leadership enforcing the process, email tests tend to get sidelined. Make running and passing visual smoke tests mandatory for production changes.
Invest in test data management – Combining real user data with mocks causes hard-to-troubleshoot side effects over time. Provision test data the emails exclusively operate on.
Adhere to CI/CD best practices – At minimum run email test suites against main branch changes. Anchor other environments like load tests and pre-production off passing these.
I hope this guide serves you well on your journey to flawless email delivery. Do drop me a note if you have any other questions!
John Doe
Email Testing Expert
