Adds tests for filtering orphaned procs

tests/utils/test_filter_orphaned_processes.py

@@ -0,0 +1,62 @@
+"""Tests for the `filter_orphaned_processes` function."""
+
+import unittest
+
+import pandas as pd
+
+from shinigami.utils import filter_orphaned_processes, INIT_PROCESS_ID
+
+
+class FilterOrphanedProcesses(unittest.TestCase):
+    """Test the identification of orphaned processes from a DataFrame of process data"""
+
+    def test_processes_are_filtered(self) -> None:
+        """Test orphaned processes are returned from a DataFrame of process data"""
+
+        input_df = pd.DataFrame({
+            'PID': [1, 2, 3, 4, 5],
+            'PPID': [0, INIT_PROCESS_ID, INIT_PROCESS_ID, 2000, 2000],
+            'PGID': [0, 0, 0, 0, 0],
+            'UID': [0, 1, 1, 2, 2],
+            'CMD': ['init', 'process_1', 'process_2', 'process_3', 'process_4']})
+
+        # Manually define the data subset (including the index) expected in the function return
+        expected_output_df = pd.DataFrame({
+            'PID': [2, 3],
+            'PPID': [INIT_PROCESS_ID, INIT_PROCESS_ID],
+            'PGID': [0, 0],
+            'UID': [1, 1],
+            'CMD': ['process_1', 'process_2']},
+            index=[1, 2])
+
+        pd.testing.assert_frame_equal(
+            filter_orphaned_processes(input_df),
+            expected_output_df)
+
+    def test_no_orphaned_processes(self) -> None:
+        """Test the returned DataFrame is empty when no orphaned processes are present"""
+
+        input_df = pd.DataFrame({
+            'PID': [1, 2, 3, 4, 5],
+            'PPID': [0, 2, 3, 4, 4],
+            'PGID': [0, 0, 0, 0, 0],
+            'UID': [0, 1, 1, 2, 2],
+            'CMD': ['init', 'process_1', 'process_2', 'process_3', 'process_4']})
+
+        self.assertTrue(filter_orphaned_processes(input_df).empty)
+
+    def test_all_orphaned_processes(self) -> None:
+        """Test the returned DataFrame matches the input DataFrame when all processes are orphaned"""
+
+        input_df = pd.DataFrame({
+            'PID': [2, 3, 4, 5],
+            'PPID': [INIT_PROCESS_ID, INIT_PROCESS_ID, INIT_PROCESS_ID, INIT_PROCESS_ID],
+            'PGID': [0, 0, 0, 0],
+            'UID': [1, 1, 2, 2],
+            'CMD': ['process_1', 'process_2', 'process_3', 'process_4']})
+
+        returned_df = filter_orphaned_processes(input_df)
+        pd.testing.assert_frame_equal(returned_df, input_df)
+
+        # Make sure the return value is an equivalent copy and not just the original DataFrame
+        self.assertIsNot(returned_df, input_df)