Run Unit Tests

SGLang uses the built-in library unittest as the testing framework.

Test Backend Runtime

cd sglang/test/srt

# Run a single file
python3 test_srt_endpoint.py

# Run a single test
python3 test_srt_endpoint.py TestSRTEndpoint.test_simple_decode

# Run a suite with multiple files
python3 run_suite.py --suite per-commit

Test Frontend Language

cd sglang/test/lang

# Run a single file
python3 test_choices.py

Adding or Updating Tests in CI

Create new test files under test/srt or test/lang depending on the type of test.
Ensure they are referenced in the respective run_suite.py (e.g., test/srt/run_suite.py) so they are picked up in CI. For most small test cases, they can be added to the per-commit-1-gpu suite. Sort the test cases alphabetically by name.
Ensure you added unittest.main() for unittest and pytest.main([__file__]) for pytest in the scripts. The CI run them via python3 test_file.py.
The CI will run some suites such as per-commit-1-gpu, per-commit-2-gpu, and nightly-1-gpu automatically. If you need special setup or custom test groups, you may modify the workflows in .github/workflows/.

Writing Elegant Test Cases

Learn from existing examples in sglang/test/srt.
Reduce the test time by using smaller models and reusing the server for multiple test cases. Launching a server takes a lot of time.
Use as few GPUs as possible. Do not run long tests with 8-gpu runners.
If the test cases take too long, considering adding them to nightly tests instead of per-commit tests.
Keep each test function focused on a single scenario or piece of functionality.
Give tests descriptive names reflecting their purpose.
Use robust assertions (e.g., assert, unittest methods) to validate outcomes.
Clean up resources to avoid side effects and preserve test independence.
Reduce the test time by using smaller models and reusing the server for multiple test cases.

Adding New Models to Nightly CI

For text models: extend global model lists variables in test_utils.py, or add more model lists
For vlms: extend the MODEL_THRESHOLDS global dictionary in test_nightly_vlms_.*.py, see here

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