What are the best practices for testing a web application before release?

Before releasing a web application, follow best practices for testing, including comprehensive unit testing to validate individual components, integration testing to ensure seamless interactions between modules, and end-to-end testing to assess overall functionality. Implement automated testing for efficiency and reliability, conduct performance testing to assess scalability, and perform security testing to identify vulnerabilities. Regularly update test cases, leverage continuous integration for ongoing validation, and employ user acceptance testing to align with user expectations.

Functional testing verifies that each function of a web application operates in line with the requirement specifications. For example, an e-commerce site's checkout process is tested to ensure that users can select items, add them to the cart, and complete purchases securely. This test checks the application flow from start to finish, confirming that all user inputs lead to the correct outputs.

In the practical world of competing priorities & strict release deadlines, following best practices are helpful to ensure good application performance: 1. Create a robust workload model, which will be a good enough representation of production volumes. Testing with too much volume will show problems that don't exist, but testing with smaller volumes may result in performance issues after release. 2. Be mindful of different variations of the same use case, like a user having 50 items in a cart instead of just one. 3. If QAs & BAs are complaining of poor user experience, you don't have to wait for a "load test report" to start analyzing performance issues. Have good observability setup in testing regions using tools like Splunk & Dynatrace.

Performance testing ensures a web app's robustness by simulating peak loads to assess speed and stability. For instance, tools like Apache JMeter or LoadRunner can test if a shopping site remains swift and secure on Black Friday, handling thousands of simultaneous users without compromising performance, thus safeguarding user experience during critical times.

Security testing scrutinizes a web app for vulnerabilities. For instance, using tools like OWASP ZAP, testers simulate attacks, seeking out weaknesses like SQL injections or XSS flaws in a banking app. The aim is to preempt breaches, ensuring that personal financial data remains ironclad against cyber threats, thus maintaining trust and compliance.

In my internship, we focused on usability testing to refine our app's user experience. We mapped out typical user journeys, then observed real users navigating the app. One scenario involved booking a service; we tracked how intuitively users could complete this task. The insights gained were pivotal, leading to a simplified booking process that significantly improved user satisfaction scores in subsequent tests.

Regression testing is essential to ensure that new code changes don't disrupt existing functionality. For example, at my previous role, after adding a new feature to our project management tool, we ran a suite of automated regression tests. These tests were crucial in confirming that the addition didn't negatively impact the task assignment feature, which was core to our application's functionality. This process helped us maintain product integrity with every update.