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tools/server/tests/README.md

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+# Server tests
+
+Python based server tests scenario using [pytest](https://docs.pytest.org/en/stable/).
+
+Tests target GitHub workflows job runners with 4 vCPU.
+
+Note: If the host architecture inference speed is faster than GitHub runners one, parallel scenario may randomly fail.
+To mitigate it, you can increase values in `n_predict`, `kv_size`.
+
+### Install dependencies
+
+`pip install -r requirements.txt`
+
+### Run tests
+
+1. Build the server
+
+```shell
+cd ../../..
+cmake -B build
+cmake --build build --target llama-server
+```
+
+2. Start the test: `./tests.sh`
+
+It's possible to override some scenario steps values with environment variables:
+
+| variable                 | description                                                                                    |
+|--------------------------|------------------------------------------------------------------------------------------------|
+| `PORT`                   | `context.server_port` to set the listening port of the server during scenario, default: `8080` |
+| `LLAMA_SERVER_BIN_PATH`  | to change the server binary path, default: `../../../build/bin/llama-server`                         |
+| `DEBUG`                  | to enable steps and server verbose mode `--verbose`                                       |
+| `N_GPU_LAYERS`           | number of model layers to offload to VRAM `-ngl --n-gpu-layers`                                |
+| `LLAMA_CACHE`            | by default server tests re-download models to the `tmp` subfolder. Set this to your cache (e.g. `$HOME/Library/Caches/llama.cpp` on Mac or `$HOME/.cache/llama.cpp` on Unix) to avoid this |
+
+To run slow tests (will download many models, make sure to set `LLAMA_CACHE` if needed):
+
+```shell
+SLOW_TESTS=1 ./tests.sh
+```
+
+To run with stdout/stderr display in real time (verbose output, but useful for debugging):
+
+```shell
+DEBUG=1 ./tests.sh -s -v -x
+```
+
+To run all the tests in a file:
+
+```shell
+./tests.sh unit/test_chat_completion.py -v -x
+```
+
+To run a single test:
+
+```shell
+./tests.sh unit/test_chat_completion.py::test_invalid_chat_completion_req
+```
+
+Hint: You can compile and run test in single command, useful for local developement:
+
+```shell
+cmake --build build -j --target llama-server && ./tools/server/tests/tests.sh
+```
+
+To see all available arguments, please refer to [pytest documentation](https://docs.pytest.org/en/stable/how-to/usage.html)
+
+### Debugging external llama-server
+It can sometimes be useful to run the server in a debugger when invesigating test
+failures. To do this, the environment variable `DEBUG_EXTERNAL=1` can be set
+which will cause the test to skip starting a llama-server itself. Instead, the
+server can be started in a debugger.
+
+Example using `gdb`:
+```console
+$ gdb --args ../../../build/bin/llama-server \
+    --host 127.0.0.1 --port 8080 \
+    --temp 0.8 --seed 42 \
+    --hf-repo ggml-org/models --hf-file tinyllamas/stories260K.gguf \
+    --batch-size 32 --no-slots --alias tinyllama-2 --ctx-size 512 \
+    --parallel 2 --n-predict 64
+```
+And a break point can be set in before running:
+```console
+(gdb) br server.cpp:4604
+(gdb) r
+main: server is listening on http://127.0.0.1:8080 - starting the main loop
+srv  update_slots: all slots are idle
+```
+
+And then the test in question can be run in another terminal:
+```console
+(venv) $ env DEBUG_EXTERNAL=1 ./tests.sh unit/test_chat_completion.py -v -x
+```
+And this should trigger the breakpoint and allow inspection of the server state
+in the debugger terminal.