docs: add docs for test-set-config

versioned_docs/version-3.0.0/running-keploy/test-set-configuration-file.md

@@ -0,0 +1,87 @@
+---
+title: Test-Set Configuration File (config.yaml)
+description: How to define per test-set configuration (like overriding appCommand) using config.yaml placed alongside mock.yaml.
+---
+
+# Test-Set Configuration File
+
+Each Keploy test-set can have its own lightweight configuration file. Create a file named `config.yaml` in the **same directory** as the corresponding `mock.yaml` (and any captured test data). This lets you override runtime parameters (like the application start command) or supply per test-set scripts/metadata without affecting other sets.
+
+## File Location
+
+```
+tests/
+	my-test-set/
+		mock.yaml          # Recorded mocks for this test-set
+		config.yaml        # Test-set specific configuration (optional)
+		...                # Any other assets
+```
+
+If `config.yaml` is absent, Keploy falls back to global/default settings.
+
+## Minimal Use Case: Override appCommand
+
+To run the application under test with a different command (env vars, flags, image, binary path, etc.) only for this test-set, place a `config.yaml` beside `mock.yaml` containing just the `appCommand` key:
+
+```yaml
+appCommand: docker run --rm --name python-api \
+	--network python-api-network \
+	-e DATABASE_URL=mysql+pymysql://user:password@mysql-db:3306/fastapi_db \
+	-e SECRET_KEY=super-secret-key-for-testing \
+	-e ACCESS_TOKEN_EXPIRE_MINUTES=5 \
+	-p 8000:8000 python-rest-api
+```
+
+That’s all you need when your only goal is to override how the app starts during replay for this specific test-set.
+
+## Available (Optional) Keys
+
+You can extend `config.yaml` later if needed. Common fields (all optional unless noted):
+
+common example -
+
+```yaml
+preScript: ""
+postScript: ""
+template: {}
+mockRegistry: null
+appCommand: <my test-set specific app command>
+metadata:
+  name: flask-mysql-app
+```
+
+| Key            | Purpose                                                                                                                    |
+| -------------- | -------------------------------------------------------------------------------------------------------------------------- |
+| `appCommand`   | Command Keploy should run to start the application for this test-set. Overrides any global/app-level command.              |
+| `preScript`    | Shell script (inline or path) executed before starting the app / replaying tests. Use for seeding DB, cleaning state, etc. |
+| `postScript`   | Shell script executed after tests finish (cleanup, exporting artifacts).                                                   |
+| `mockId`       | Explicit identifier if you maintain multiple mock groups in the same folder and need disambiguation.                       |
+| `template`     | A map/object for advanced templating or variable substitution (future/advanced usage).                                     |
+| `mockRegistry` | (Optional) Registry or remote reference for fetching mocks if they aren’t local.                                           |
+| `metadata`     | Arbitrary informational fields (e.g., `name`, `owner`, `tags`). Non-functional but useful for organization.                |
+
+> Note: Only include the keys you actually need. Unused keys can be omitted entirely.
+
+## Tips & Best Practices
+
+1. Keep the minimal override: if you only change the start command, only keep `appCommand`—simpler diffs and fewer merge conflicts.
+2. Avoid storing secrets directly; prefer referencing environment files or secret managers.
+3. Use descriptive `metadata.name` to make CI logs clearer when multiple test-sets run.
+4. Validate the command manually once before relying on it in automated replay.
+
+## Troubleshooting
+
+| Symptom                             | Likely Cause                                                        | Fix                                                       |
+| ----------------------------------- | ------------------------------------------------------------------- | --------------------------------------------------------- |
+| App doesn’t start for this test-set | Typo in `appCommand` or missing image                               | Run the command locally; ensure image/tag exists.         |
+| Pre/post script not executed        | Wrong key name (`preScript`/`postScript`) or YAML indentation error | Validate YAML (e.g., with `yamllint`) and check spelling. |
+| Wrong mocks used                    | Missing/incorrect `mockId` when multiple sets present               | Add/adjust `mockId` or standardize directory structure.   |
+
+## Quick Validation Checklist
+
+- `config.yaml` sits beside `mock.yaml`.
+- YAML parses (`yamllint config.yaml`).
+- Only necessary keys included.
+- `appCommand` works standalone in your shell.
+
+---