Restructure tests to match providers/ layout, add parameterized platform fixture

Move test files from tests/cluster/platform/, tests/cluster/k8s/, and
tests/kubernetes/ into tests/cluster/providers/{gcp,k8s}/ to mirror the
source layout under src/iris/cluster/providers/. Add a shared conftest.py
with parameterized gcp/coreweave platform fixtures. Update imports in
test_autoscaler.py, test_snapshot_reconciliation.py, and test_vm_lifecycle.py
to reference the new fakes module path.

Author: rjpower

lib/iris/tests/cluster/controller/test_autoscaler.py

@@ -47,7 +47,7 @@
 from iris.cluster.types import WorkerStatus
 from iris.rpc import cluster_pb2, config_pb2, vm_pb2
 from iris.time_utils import Duration, Timestamp
-from tests.cluster.platform.fakes import FailureMode, FakePlatform, FakePlatformConfig
+from tests.cluster.providers.fakes import FailureMode, FakePlatform, FakePlatformConfig
 
 # --- Test fixtures and helpers ---
 

lib/iris/tests/cluster/k8s/__init__.py …iris/tests/cluster/providers/__init__.pylib/iris/tests/cluster/k8s/__init__.py renamed to lib/iris/tests/cluster/providers/__init__.py lib/iris/tests/cluster/k8s/__init__.py renamed to lib/iris/tests/cluster/providers/__init__.py

@@ -0,0 +1,46 @@
+# Copyright The Marin Authors
+# SPDX-License-Identifier: Apache-2.0
+
+"""Shared fixtures for provider tests.
+
+Provides parameterized platform fixtures that allow protocol-level tests
+to run against both GCP (InMemoryGcpService DRY_RUN) and CoreWeave
+(InMemoryK8sService) backends.
+"""
+
+from __future__ import annotations
+
+import pytest
+
+from iris.cluster.providers.gcp.fake_service import InMemoryGcpService
+from iris.cluster.providers.gcp.platform import GcpPlatform
+from iris.cluster.providers.k8s.fake_service import InMemoryK8sService
+from iris.cluster.providers.k8s.platform import CoreweavePlatform
+from iris.cluster.service_mode import ServiceMode
+from iris.rpc import config_pb2
+
+
+@pytest.fixture
+def gcp_platform():
+    """GcpPlatform backed by InMemoryGcpService for dry-run testing."""
+    gcp_service = InMemoryGcpService(mode=ServiceMode.DRY_RUN, project_id="test-project")
+    gcp_config = config_pb2.GcpPlatformConfig(project_id="test-project", zones=["us-central2-b"])
+    return GcpPlatform(gcp_config, label_prefix="iris", gcp_service=gcp_service)
+
+
+@pytest.fixture
+def coreweave_platform():
+    """CoreweavePlatform backed by InMemoryK8sService."""
+    k8s = InMemoryK8sService(namespace="iris")
+    config = config_pb2.CoreweavePlatformConfig(region="LGA1", namespace="iris")
+    platform = CoreweavePlatform(config=config, label_prefix="iris", poll_interval=0.05, kubectl=k8s)
+    yield platform
+    platform.shutdown()
+
+
+@pytest.fixture(params=["gcp", "coreweave"])
+def platform(request, gcp_platform, coreweave_platform):
+    """Parameterized fixture yielding each Platform implementation in turn."""
+    if request.param == "gcp":
+        return gcp_platform
+    return coreweave_platform