[CI/UT] Add ut for parallel_state.py (#1460)

### What this PR does / why we need it?
 Add ut for parallel_state.py

### Does this PR introduce _any_ user-facing change?
N/A

### How was this patch tested?
 python -m unittest  test_parallel_state.py

---------

Signed-off-by: wangyanhui-cmss <wangyanhui_yewu@cmss.chinamobile.com>

tests/ut/distributed/test_parallel_state.py

@@ -0,0 +1,193 @@
+import unittest
+from unittest.mock import MagicMock, patch
+
+import pytest
+from vllm.distributed.parallel_state import GroupCoordinator
+
+import vllm_ascend
+from vllm_ascend.distributed.parallel_state import (
+    destory_ascend_model_parallel, get_ep_group, get_etp_group,
+    init_ascend_model_parallel, model_parallel_initialized)
+
+
+class TestParallelState(unittest.TestCase):
+
+    @patch('vllm_ascend.distributed.parallel_state._EP',
+           new_callable=lambda: MagicMock(spec=GroupCoordinator))
+    def test_get_ep_group_when_initialized(self, mock_ep):
+        # Act
+        result = get_ep_group()
+
+        # Assert
+        assert isinstance(result, GroupCoordinator)
+
+    @patch('vllm_ascend.distributed.parallel_state._EP', None)
+    def test_get_ep_group_when_not_initialized(self):
+        # Act & Assert
+        with pytest.raises(AssertionError) as excinfo:
+            get_ep_group()
+        assert "expert model parallel group is not initialized" in str(
+            excinfo.value)
+
+    @patch('vllm_ascend.distributed.parallel_state._ETP',
+           new_callable=lambda: MagicMock(spec=GroupCoordinator))
+    def test_get_etp_group_when_initialized(self, mock_etp):
+        # Act
+        result = get_etp_group()
+
+        # Assert
+        assert isinstance(result, GroupCoordinator)
+
+    @patch('vllm_ascend.distributed.parallel_state._ETP', None)
+    def test_get_etp_group_when_not_initialized(self):
+        # Act & Assert
+        with pytest.raises(AssertionError) as excinfo:
+            get_etp_group()
+        assert "expert tensor parallel group is not initialized" in str(
+            excinfo.value)
+
+    @patch('vllm_ascend.distributed.parallel_state._ETP', None)
+    @patch('vllm_ascend.distributed.parallel_state._EP', None)
+    def test_model_parallel_initialized_when_both_none(self):
+        # Act & Assert
+        assert not model_parallel_initialized()
+
+    @patch('vllm_ascend.distributed.parallel_state._ETP',
+           new_callable=lambda: MagicMock(spec=GroupCoordinator))
+    @patch('vllm_ascend.distributed.parallel_state._EP', None)
+    def test_model_parallel_initialized_when_ep_none(self, mock_etp):
+        # Act & Assert
+        assert not model_parallel_initialized()
+
+    @patch('vllm_ascend.distributed.parallel_state._ETP', None)
+    @patch('vllm_ascend.distributed.parallel_state._EP',
+           new_callable=lambda: MagicMock(spec=GroupCoordinator))
+    def test_model_parallel_initialized_when_etp_none(self, mock_ep):
+        # Act & Assert
+        assert not model_parallel_initialized()
+
+    @patch('vllm_ascend.distributed.parallel_state._ETP',
+           new_callable=lambda: MagicMock(spec=GroupCoordinator))
+    @patch('vllm_ascend.distributed.parallel_state._EP',
+           new_callable=lambda: MagicMock(spec=GroupCoordinator))
+    def test_model_parallel_initialized_when_etp_initialized(
+            self, mock_ep, mock_etp):
+        # Act & Assert
+        assert model_parallel_initialized()
+
+    @patch('vllm_ascend.distributed.parallel_state._ETP',
+           new_callable=lambda: MagicMock(spec=GroupCoordinator))
+    @patch('vllm_ascend.distributed.parallel_state._EP',
+           new_callable=lambda: MagicMock(spec=GroupCoordinator))
+    def test_destroy_when_both_exist(self, mock_ep, mock_etp):
+        # Act
+        destory_ascend_model_parallel()
+        # Assert
+        mock_ep.destroy.assert_called_once()
+        mock_etp.destroy.assert_called_once()
+        assert vllm_ascend.distributed.parallel_state._ETP is None
+        assert vllm_ascend.distributed.parallel_state._EP is None
+
+    @patch('vllm_ascend.distributed.parallel_state._ETP', None)
+    @patch('vllm_ascend.distributed.parallel_state._EP',
+           new_callable=lambda: MagicMock())
+    def test_destory_ascend_model_parallel_when_etp_none(self, mock_ep):
+        # Act
+        destory_ascend_model_parallel()
+        # Assert
+        mock_ep.destroy.assert_called_once()
+        assert vllm_ascend.distributed.parallel_state._EP is None
+        assert vllm_ascend.distributed.parallel_state._ETP is None
+
+    @patch('vllm_ascend.distributed.parallel_state._ETP',
+           new_callable=lambda: MagicMock())
+    @patch('vllm_ascend.distributed.parallel_state._EP', None)
+    def test_destory_ascend_model_parallel_when_ep_none(self, mock_etp):
+        # Act
+        destory_ascend_model_parallel()
+        # Assert
+        mock_etp.destroy.assert_called_once()
+        assert vllm_ascend.distributed.parallel_state._ETP is None
+        assert vllm_ascend.distributed.parallel_state._EP is None
+
+    @patch('vllm_ascend.distributed.parallel_state._ETP', None)
+    @patch('vllm_ascend.distributed.parallel_state._EP', None)
+    def test_destory_ascend_model_parallel_when_both_none(self):
+        # Act
+        destory_ascend_model_parallel()
+        # Assert
+        assert vllm_ascend.distributed.parallel_state._ETP is None
+        assert vllm_ascend.distributed.parallel_state._EP is None
+
+    @patch('torch.distributed.is_initialized', return_value=True)
+    @patch('torch.distributed.get_world_size', return_value=8)
+    @patch('vllm_ascend.distributed.parallel_state.get_world_group',
+           return_value=MagicMock(device_group='npu:0', local_rank=0))
+    @patch('torch.distributed.get_backend', return_value='hccl')
+    @patch('vllm_ascend.distributed.parallel_state.init_model_parallel_group')
+    @patch('vllm_ascend.distributed.parallel_state.model_parallel_initialized',
+           return_value=False)
+    def test_init_ascend_model_parallel_normal_case(
+            self, mock_mp_init, mock_init_group, mock_get_backend,
+            mock_world_group, mock_get_world_size, mock_is_init):
+        """Test normal initialization with default parameters"""
+        # Act
+        init_ascend_model_parallel()
+        # Assert
+        mock_init_group.assert_any_call([[0, 1, 2, 3, 4, 5, 6, 7]],
+                                        0,
+                                        'hccl',
+                                        group_name="ep")
+        mock_init_group.assert_any_call([[0]], 0, 'hccl', group_name="etp")
+        self.assertIsNotNone(vllm_ascend.distributed.parallel_state._EP)
+        self.assertIsNotNone(vllm_ascend.distributed.parallel_state._ETP)
+
+    @patch('vllm_ascend.distributed.parallel_state.model_parallel_initialized',
+           return_value=True)
+    def test_init_ascend_model_parallel_skip_if_initialized(
+            self, mock_mp_init):
+        """Test skipping when model parallel already initialized"""
+        with patch.object(vllm_ascend.distributed.parallel_state,
+                          '_EP') as mock_ep, patch.object(
+                              vllm_ascend.distributed.parallel_state,
+                              '_ETP') as mock_etp:
+            # Act
+            init_ascend_model_parallel()
+            # Assert
+            mock_ep.assert_not_called()
+            mock_etp.assert_not_called()
+
+    @patch('torch.distributed.is_initialized', return_value=False)
+    def test_init_ascend_model_parallel_assert_dist_not_init(
+            self, mock_is_init):
+        """Test assertion when distributed not initialized"""
+        # Act & Assert
+        with self.assertRaises(AssertionError):
+            init_ascend_model_parallel()
+
+    @patch('torch.distributed.is_initialized', return_value=True)
+    @patch('torch.distributed.get_world_size', return_value=8)
+    @patch('vllm_ascend.distributed.parallel_state.get_world_group',
+           return_value=MagicMock(device_group='npu:0', local_rank=1))
+    @patch('torch.distributed.get_backend', return_value='hccl')
+    @patch('vllm_ascend.distributed.parallel_state.init_model_parallel_group')
+    @patch('vllm_ascend.distributed.parallel_state.model_parallel_initialized',
+           return_value=False)
+    def test_init_ascend_model_parallel_custom_params(
+            self, mock_mp_init, mock_init_group, mock_get_backend,
+            mock_world_group, mock_get_world_size, mock_is_init):
+        """Test initialization with custom parallel sizes"""
+        # Act
+        init_ascend_model_parallel(expert_parallel_size=2,
+                                   expert_tensor_parallel_size=4,
+                                   world_size=8,
+                                   backend='hccl')
+        #Assert
+        mock_init_group.assert_any_call([[0, 4], [1, 5], [2, 6], [3, 7]],
+                                        1,
+                                        'hccl',
+                                        group_name="ep")
+        mock_init_group.assert_any_call([[0, 1, 2, 3], [4, 5, 6, 7]],
+                                        1,
+                                        'hccl',
+                                        group_name="etp")