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/agents/fixtures.py

@@ -0,0 +1,63 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the terms described in the LICENSE file in
+# the root directory of this source tree.
+
+import tempfile
+
+import pytest
+import pytest_asyncio
+
+from llama_stack.distribution.datatypes import Api, Provider
+
+from llama_stack.providers.impls.meta_reference.agents import (
+    MetaReferenceAgentsImplConfig,
+)
+
+from llama_stack.providers.tests.resolver import resolve_impls_for_test_v2
+from llama_stack.providers.utils.kvstore.config import SqliteKVStoreConfig
+
+from ..conftest import ProviderFixture
+
+
+@pytest.fixture(scope="session")
+def agents_meta_reference() -> ProviderFixture:
+    sqlite_file = tempfile.NamedTemporaryFile(delete=False, suffix=".db")
+    return ProviderFixture(
+        providers=[
+            Provider(
+                provider_id="meta-reference",
+                provider_type="meta-reference",
+                config=MetaReferenceAgentsImplConfig(
+                    # TODO: make this an in-memory store
+                    persistence_store=SqliteKVStoreConfig(
+                        db_path=sqlite_file.name,
+                    ),
+                ).model_dump(),
+            )
+        ],
+    )
+
+
+AGENTS_FIXTURES = ["meta_reference"]
+
+
+@pytest_asyncio.fixture(scope="session")
+async def agents_stack(request):
+    fixture_dict = request.param
+
+    providers = {}
+    provider_data = {}
+    for key in ["inference", "safety", "memory", "agents"]:
+        fixture = request.getfixturevalue(f"{key}_{fixture_dict[key]}")
+        providers[key] = fixture.providers
+        if fixture.provider_data:
+            provider_data.update(fixture.provider_data)
+
+    impls = await resolve_impls_for_test_v2(
+        [Api.agents, Api.inference, Api.safety, Api.memory],
+        providers,
+        provider_data,
+    )
+    return impls[Api.agents], impls[Api.memory]