test: add unit tests for nested virtualization detection

Add test_nested_virtualization.py covering _supports_nested_virtualization()
in VMLauncher. Tests verify that C8i, M8i, R8i, C7i, M7i, R7i, X8i,
I7i families (and flex/d variants) are correctly detected as supporting
nested virtualization, while older families (c5a, c6g, t3, m5) are not.

Signed-off-by: Norbert Manthey <nmanthey@amazon.de>

Author: nmanthey

tests/test_nested_virtualization.py

@@ -0,0 +1,82 @@
+"""Unit tests for nested virtualization support in launch_vm."""
+
+__authors__ = ["Norbert Manthey <nmanthey@amazon.de>"]
+__copyright__ = "Copyright Amazon.com, Inc. or its affiliates. All Rights Reserved."
+# SPDX-License-Identifier: Apache-2.0
+
+from unittest.mock import patch, MagicMock
+
+import pytest
+
+from kernel_ci_cloud_labs.launch_vm import VMLauncher
+
+
+@pytest.fixture
+def _mock_boto3():
+    """Patch boto3 so VMLauncher.__init__ doesn't need real AWS credentials."""
+    with patch("kernel_ci_cloud_labs.launch_vm.boto3") as mock_boto:
+        mock_boto.client.return_value = MagicMock()
+        yield mock_boto
+
+
+class TestNestedVirtualization:
+    """Tests for _supports_nested_virtualization and CpuOptions."""
+
+    def _make_launcher(self, instance_type, _mock_boto3):
+        """Create a VMLauncher with a given instance_type, mocking AWS."""
+        vm_config = {
+            "instance_type": instance_type,
+            "ami_id": "ami-test123",
+            "role_name": "test-role",
+            "s3_bucket": "test-bucket",
+            "run_prefix": "run_test",
+        }
+        return VMLauncher(vm_config)
+
+    def test_c8i_supports_nested(self, _mock_boto3):
+        launcher = self._make_launcher("c8i.4xlarge", _mock_boto3)
+        assert launcher._supports_nested_virtualization() is True
+
+    def test_c8i_flex_supports_nested(self, _mock_boto3):
+        launcher = self._make_launcher("c8i-flex.2xlarge", _mock_boto3)
+        assert launcher._supports_nested_virtualization() is True
+
+    def test_m8i_supports_nested(self, _mock_boto3):
+        launcher = self._make_launcher("m8i.large", _mock_boto3)
+        assert launcher._supports_nested_virtualization() is True
+
+    def test_r8i_supports_nested(self, _mock_boto3):
+        launcher = self._make_launcher("r8i.xlarge", _mock_boto3)
+        assert launcher._supports_nested_virtualization() is True
+
+    def test_c7i_supports_nested(self, _mock_boto3):
+        launcher = self._make_launcher("c7i.2xlarge", _mock_boto3)
+        assert launcher._supports_nested_virtualization() is True
+
+    def test_m7i_supports_nested(self, _mock_boto3):
+        launcher = self._make_launcher("m7i.xlarge", _mock_boto3)
+        assert launcher._supports_nested_virtualization() is True
+
+    def test_x8i_supports_nested(self, _mock_boto3):
+        launcher = self._make_launcher("x8i.large", _mock_boto3)
+        assert launcher._supports_nested_virtualization() is True
+
+    def test_i7i_supports_nested(self, _mock_boto3):
+        launcher = self._make_launcher("i7i.xlarge", _mock_boto3)
+        assert launcher._supports_nested_virtualization() is True
+
+    def test_c5a_does_not_support_nested(self, _mock_boto3):
+        launcher = self._make_launcher("c5a.4xlarge", _mock_boto3)
+        assert launcher._supports_nested_virtualization() is False
+
+    def test_c6g_does_not_support_nested(self, _mock_boto3):
+        launcher = self._make_launcher("c6g.4xlarge", _mock_boto3)
+        assert launcher._supports_nested_virtualization() is False
+
+    def test_t3_does_not_support_nested(self, _mock_boto3):
+        launcher = self._make_launcher("t3.micro", _mock_boto3)
+        assert launcher._supports_nested_virtualization() is False
+
+    def test_m5_does_not_support_nested(self, _mock_boto3):
+        launcher = self._make_launcher("m5.large", _mock_boto3)
+        assert launcher._supports_nested_virtualization() is False