Optimizes niceness and cpulimit usage

tests/unit/test_process.py

@@ -15,6 +15,9 @@ from ffx.process import (  # noqa: E402
     COMMAND_NOT_FOUND_RETURN_CODE,
     COMMAND_TIMED_OUT_RETURN_CODE,
     executeProcess,
+    getWrappedCommandSequence,
+    normalizeCpuPercent,
+    normalizeNiceness,
 )
 
 
@@ -47,6 +50,39 @@ class ProcessTests(unittest.TestCase):
         self.assertIn("Command timed out", err)
         self.assertIn(sys.executable, err)
 
+    def test_get_wrapped_command_sequence_leaves_command_unwrapped_when_limits_disabled(self):
+        wrapped = getWrappedCommandSequence(
+            ["ffmpeg", "-i", "input.mkv"],
+            context={"resource_limits": {"niceness": None, "cpu_percent": None}},
+        )
+
+        self.assertEqual(["ffmpeg", "-i", "input.mkv"], wrapped)
+
+    def test_get_wrapped_command_sequence_wraps_nice_when_configured(self):
+        wrapped = getWrappedCommandSequence(
+            ["ffmpeg", "-i", "input.mkv"],
+            context={"resource_limits": {"niceness": 5, "cpu_percent": None}},
+        )
+
+        self.assertEqual(["nice", "-n", "5", "ffmpeg", "-i", "input.mkv"], wrapped)
+
+    def test_get_wrapped_command_sequence_wraps_cpulimit_around_nice_when_both_configured(self):
+        wrapped = getWrappedCommandSequence(
+            ["ffmpeg", "-i", "input.mkv"],
+            context={"resource_limits": {"niceness": 5, "cpu_percent": 42}},
+        )
+
+        self.assertEqual(
+            ["cpulimit", "-l", "42", "--", "nice", "-n", "5", "ffmpeg", "-i", "input.mkv"],
+            wrapped,
+        )
+
+    def test_normalize_niceness_accepts_disabled_sentinel(self):
+        self.assertIsNone(normalizeNiceness(99))
+
+    def test_normalize_cpu_percent_accepts_disabled_sentinel(self):
+        self.assertIsNone(normalizeCpuPercent(0))
+
 
 if __name__ == "__main__":
     unittest.main()