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/memory/conftest.py

@@ -0,0 +1,29 @@
+# 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
+
+from .fixtures import MEMORY_FIXTURES
+
+
+def pytest_configure(config):
+    for fixture_name in MEMORY_FIXTURES:
+        config.addinivalue_line(
+            "markers",
+            f"{fixture_name}: marks tests as {fixture_name} specific",
+        )
+
+
+def pytest_generate_tests(metafunc):
+    if "memory_stack" in metafunc.fixturenames:
+        metafunc.parametrize(
+            "memory_stack",
+            [
+                pytest.param(fixture_name, marks=getattr(pytest.mark, fixture_name))
+                for fixture_name in MEMORY_FIXTURES
+            ],
+            indirect=True,
+        )