added tests help

tests/tests.md

@@ -1,26 +1,32 @@
-# How to run the tests
+# MOSAICapp Test Suite
 
-#### Install pytest if not already installed
-pip install pytest
-
-#### Run all tests
-pytest tests/ -v
-
-#### Run specific test file (eg test_core_functions.py)
-pytest tests/test_core_functions.py -v
+This directory contains the automated tests for the MOSAICapp software.
 
+## File Structure
 
-# Which tests to run:
+### 1. `conftest.py`
+Contains **fixtures** (setup code) shared across all tests. It generates temporary CSV files and dummy datasets so tests can run without external data dependencies.
 
-### Test utility functions (fast)
-pytest tests/test_core_functions.py -v
-
-### Integration tests (slow, run occasionally):
+### 2. `test_core_functions.py` (Fast)
+Unit tests for the `mosaic_core` utility functions. These run instantly.
+- **Slugify:** Checks filename sanitisation.
+- **CacheIO:** Verifies that topic labels can be saved/loaded from JSON.
+- **Device Resolution:** Ensures the app correctly selects CPU/GPU/MPS devices.
 
-- Without LLM tests
-pytest tests/test_integration.py -v
+### 3. `test_integration.py` (Slow)
+Integration tests that run the actual ML pipeline.
+- **Embeddings:** Loads the `sentence-transformers` model and checks vector output.
+- **Topic Modelling:** Runs a minimal BERTopic pipeline (UMAP + HDBSCAN) on dummy data.
+- **LLM labeling:** (Optional) Tests the HuggingFace API connection if `HF_TOKEN` is present in the environment.
 
-- With LLM tests (needs token)
-HF_TOKEN=your_token pytest tests/test_integration.py -v
+## How to Run
 
+**Run everything:**
+```bash
+pytest tests/ -v
+```
 
+**Run only fast tests:**
+```bash
+pytest tests/test_core_functions.py -v
+```