Fast-executing tests require less time and are executed more frequently, contributing to improved code quality. Therefore a high test execution speed is important.
Measures
- General code optimizations such as faster algorithms, data types, etc.
- Test type segregation: Unit tests typically run much faster than other types of tests. For large test suites, consider running unit tests regularly on the developer's local machine, while scheduling more resource-intensive tests to run at a fixed rate in a continuous integration environment, for example.
- Partial testing: You don't have to run all tests every time. Often, it is sufficient to run only the tests related to recently changed code.
- Mock slow dependencies to minimize code execution time, especially operations such as I/O, transaction management, and networking.
- Prefer in-memory databases during testing for cleaner and faster operations compared to standard databases.
- Identify performance bottlenecks by increasing the number of threads:
- If execution time remains constant, CPU is the bottleneck. Mitigate with faster CPUs, more cores, or additional machines.
- If execution time decreases, I/O is the bottleneck. Use more threads, faster memory (such as SSDs), or additional storage.
- Improve I/O speed by using RAM disks, such as Linux's tmpfs tool. Configure your tests to direct all file interactions to the RAM disk.
- Parallelize test execution. Multiple threads can improve execution speed even on single-core processors by keeping the CPU busy while other threads wait for disk I/O.
- Offload CPU-intensive tasks to cloud-based computing resources:
- Upload project files to the cloud.
- The cloud service builds the project, runs tests, and generates a test report.
- Upon completion, download the test report from the cloud.