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/safety/fixtures.py

@@ -0,0 +1,90 @@
+# 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 pytest
+import pytest_asyncio
+
+from llama_stack.distribution.datatypes import Api, Provider
+from llama_stack.providers.adapters.safety.together import TogetherSafetyConfig
+from llama_stack.providers.impls.meta_reference.safety import (
+    LlamaGuardShieldConfig,
+    SafetyConfig,
+)
+
+from llama_stack.providers.tests.resolver import resolve_impls_for_test_v2
+
+from ..conftest import ProviderFixture
+from ..env import get_env_or_fail
+
+
+@pytest.fixture(scope="session")
+def safety_model(request):
+    if hasattr(request, "param"):
+        return request.param
+    return request.config.getoption("--safety-model", None)
+
+
+@pytest.fixture(scope="session")
+def safety_meta_reference(safety_model) -> ProviderFixture:
+    return ProviderFixture(
+        providers=[
+            Provider(
+                provider_id="meta-reference",
+                provider_type="meta-reference",
+                config=SafetyConfig(
+                    llama_guard_shield=LlamaGuardShieldConfig(
+                        model=safety_model,
+                    ),
+                ).model_dump(),
+            )
+        ],
+    )
+
+
+@pytest.fixture(scope="session")
+def safety_together() -> ProviderFixture:
+    return ProviderFixture(
+        providers=[
+            Provider(
+                provider_id="together",
+                provider_type="remote::together",
+                config=TogetherSafetyConfig().model_dump(),
+            )
+        ],
+        provider_data=dict(
+            together_api_key=get_env_or_fail("TOGETHER_API_KEY"),
+        ),
+    )
+
+
+SAFETY_FIXTURES = ["meta_reference", "together"]
+
+
+@pytest_asyncio.fixture(scope="session")
+async def safety_stack(inference_model, safety_model, request):
+    # We need an inference + safety fixture to test safety
+    fixture_dict = request.param
+    inference_fixture = request.getfixturevalue(
+        f"inference_{fixture_dict['inference']}"
+    )
+    safety_fixture = request.getfixturevalue(f"safety_{fixture_dict['safety']}")
+
+    providers = {
+        "inference": inference_fixture.providers,
+        "safety": safety_fixture.providers,
+    }
+    provider_data = {}
+    if inference_fixture.provider_data:
+        provider_data.update(inference_fixture.provider_data)
+    if safety_fixture.provider_data:
+        provider_data.update(safety_fixture.provider_data)
+
+    impls = await resolve_impls_for_test_v2(
+        [Api.safety, Api.shields, Api.inference],
+        providers,
+        provider_data,
+    )
+    return impls[Api.safety], impls[Api.shields]