Add a test case

Author: dabico

instrumentation/opentelemetry-instrumentation-system-metrics/tests/test_system_metrics.py

@@ -14,6 +14,7 @@
 
 # pylint: disable=protected-access,too-many-lines
 
+import importlib.util
 import sys
 from collections import namedtuple
 from platform import python_implementation
@@ -1091,3 +1092,37 @@ def test_that_correct_config_is_read(self):
             instrumentor.instrument(meter_provider=meter_provider)
             meter_provider.force_flush()
             instrumentor.uninstrument()
+
+    def test_linux_missing_vmstat_removes_swap_metrics(self):
+        with (
+            mock.patch(
+                target="psutil.LINUX",
+                new=True,
+            ),
+            mock.patch(
+                target="psutil.PROCFS_PATH",
+                new="/bogus/path/to/procfs",
+                create=True,
+            ),
+        ):
+            # Import the module into an isolated, temporary module object under the patched context
+            spec = importlib.util.find_spec(
+                "opentelemetry.instrumentation.system_metrics"
+            )
+            assert (
+                spec and spec.origin
+            ), "Could not find system_metrics module spec"
+
+            tmp_spec = importlib.util.spec_from_file_location(
+                name="tmp_system_metrics_for_test",
+                location=spec.origin,
+            )
+            module = importlib.util.module_from_spec(tmp_spec)
+
+            # Ensure relative imports inside the module resolve correctly
+            module.__package__ = "opentelemetry.instrumentation.system_metrics"
+            tmp_spec.loader.exec_module(module)
+
+            config = getattr(module, "_DEFAULT_CONFIG")
+            assert "system.swap.usage" not in config
+            assert "system.swap.utilization" not in config