Add README to tests

tests/README.md

@@ -1,4 +1,32 @@
-# Bless tests
+# HyperQueue test suite
+This directory contains the Python test suite of HyperQueue.
+
+## Usage
+The following commands are supposed to be executed from the root HyperQueue directory.
+
+1) Install `pytest` and other dependencies
+    ```bash
+    $ python -m pip install tests/requirements.txt
+    ```
+2) Run tests
+    ```bash
+    $ python -m pytest tests
+    ```
+
+You can speed up test execution by running them in parallel:
+```bash
+$ python -m pytest tests -n16
+```
+
+### Running autoalloc tests
+There are several tests for the automatic allocator that require the presence of an external service (PBS).
+If you are on a system that has these services installed, you can run these tests with the `pbs` mark:
+```bash
+$ python -m pytest tests -m pbs
+```
+
+## Blessing
+You can bless tests with the following command:
 ```bash
 $ python -m pytest --inline-snapshot=create
 ```