Significantly simpler and malleable test setup (#360)

* Significantly simpler and malleable test setup

* convert memory tests

* refactor fixtures and add support for composable fixtures

* Fix memory to use the newer fixture organization

* Get agents tests working

* Safety tests work

* yet another refactor to make this more general

now it accepts --inference-model, --safety-model options also

* get multiple providers working for meta-reference (for inference + safety)

* Add README.md

---------

Co-authored-by: Ashwin Bharambe <ashwin@meta.com>

llama_stack/providers/tests/resolver.py

@@ -7,7 +7,7 @@
 import json
 import os
 from datetime import datetime
-from typing import Any, Dict, List
+from typing import Any, Dict, List, Optional
 
 import yaml
 
@@ -18,6 +18,28 @@ from llama_stack.distribution.request_headers import set_request_provider_data
 from llama_stack.distribution.resolver import resolve_impls
 
 
+async def resolve_impls_for_test_v2(
+    apis: List[Api],
+    providers: Dict[str, List[Provider]],
+    provider_data: Optional[Dict[str, Any]] = None,
+):
+    run_config = dict(
+        built_at=datetime.now(),
+        image_name="test-fixture",
+        apis=apis,
+        providers=providers,
+    )
+    run_config = parse_and_maybe_upgrade_config(run_config)
+    impls = await resolve_impls(run_config, get_provider_registry())
+
+    if provider_data:
+        set_request_provider_data(
+            {"X-LlamaStack-ProviderData": json.dumps(provider_data)}
+        )
+
+    return impls
+
+
 async def resolve_impls_for_test(api: Api, deps: List[Api] = None):
     if "PROVIDER_CONFIG" not in os.environ:
         raise ValueError(