test: improve coverage for Windows platform detection

- Add test for is_psutil_available() with small nice value
- Add comprehensive error handling tests for count_physical_cpus() on Windows:
  - CalledProcessError
  - TimeoutExpired
  - ValueError for invalid output

This brings test coverage to 100% for the Windows-specific code paths added in the PR.

Author: benoit-cty

tests/test_cpu.py

@@ -28,6 +28,14 @@ def test_is_psutil_available_with_nice(self, mock_cpu_times):
         mock_cpu_times.return_value = mock_times
         self.assertTrue(is_psutil_available())
 
+    @mock.patch("psutil.cpu_times")
+    def test_is_psutil_available_with_small_nice(self, mock_cpu_times):
+        # Test when nice attribute is too small
+        mock_times = mock.Mock()
+        mock_times.nice = 0.00001
+        mock_cpu_times.return_value = mock_times
+        self.assertFalse(is_psutil_available())
+
     @mock.patch("psutil.cpu_times")
     def test_is_psutil_available_without_nice(self, mock_cpu_times):
         # Create a mock without 'nice' attribute (like Windows)
@@ -341,6 +349,28 @@ def test_count_physical_cpus_windows(self):
             ):
                 assert count_physical_cpus() == 1
 
+    def test_count_physical_cpus_windows_with_error(self):
+        with mock.patch("platform.system", return_value="Windows"):
+            # Test CalledProcessError
+            with mock.patch(
+                "subprocess.run",
+                side_effect=subprocess.CalledProcessError(1, "powershell"),
+            ):
+                assert count_physical_cpus() == 1
+
+            # Test TimeoutExpired
+            with mock.patch(
+                "subprocess.run",
+                side_effect=subprocess.TimeoutExpired("powershell", 10),
+            ):
+                assert count_physical_cpus() == 1
+
+            # Test ValueError when converting invalid output
+            with mock.patch(
+                "subprocess.run", return_value=mock.Mock(returncode=0, stdout="invalid")
+            ):
+                assert count_physical_cpus() == 1
+
     def test_count_physical_cpus_linux(self):
         with mock.patch("platform.system", return_value="Linux"):
             lscpu_output = "Socket(s): 2\n"