Add comprehensive tests for Assets API (14 tests)

Tests include:
- Asset model validation (8 tests)
  - Asset, AssetRename, FolderCreate models
  - Field validation, filename validation
  - Size helper methods (size_mb, size_kb)
  - Slug normalization

- Sync AssetsEndpoint (6 tests)
  - List, get, rename, delete operations
  - Folder listing
  - Validation error handling

All 14 tests passing. Achieves comprehensive coverage for Assets API.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>

tests/endpoints/test_assets.py

@@ -0,0 +1,163 @@
+"""Tests for Assets endpoint."""
+
+from unittest.mock import Mock
+
+import pytest
+
+from wikijs.endpoints import AssetsEndpoint
+from wikijs.exceptions import APIError, ValidationError
+from wikijs.models import Asset, AssetFolder
+
+
+class TestAssetsEndpoint:
+    """Test AssetsEndpoint class."""
+
+    @pytest.fixture
+    def client(self):
+        """Create mock client."""
+        mock_client = Mock()
+        mock_client.base_url = "https://wiki.example.com"
+        return mock_client
+
+    @pytest.fixture
+    def endpoint(self, client):
+        """Create AssetsEndpoint instance."""
+        return AssetsEndpoint(client)
+
+    def test_list_assets(self, endpoint):
+        """Test listing assets."""
+        mock_response = {
+            "data": {
+                "assets": {
+                    "list": [
+                        {
+                            "id": 1,
+                            "filename": "test.png",
+                            "ext": "png",
+                            "kind": "image",
+                            "mime": "image/png",
+                            "fileSize": 1024,
+                            "folderId": 0,
+                            "folder": None,
+                            "authorId": 1,
+                            "authorName": "Admin",
+                            "createdAt": "2024-01-01T00:00:00Z",
+                            "updatedAt": "2024-01-01T00:00:00Z",
+                        }
+                    ]
+                }
+            }
+        }
+        endpoint._post = Mock(return_value=mock_response)
+
+        assets = endpoint.list()
+
+        assert len(assets) == 1
+        assert isinstance(assets[0], Asset)
+        assert assets[0].filename == "test.png"
+
+    def test_get_asset(self, endpoint):
+        """Test getting an asset."""
+        mock_response = {
+            "data": {
+                "assets": {
+                    "single": {
+                        "id": 1,
+                        "filename": "test.png",
+                        "ext": "png",
+                        "kind": "image",
+                        "mime": "image/png",
+                        "fileSize": 1024,
+                        "folderId": 0,
+                        "folder": None,
+                        "authorId": 1,
+                        "authorName": "Admin",
+                        "createdAt": "2024-01-01T00:00:00Z",
+                        "updatedAt": "2024-01-01T00:00:00Z",
+                    }
+                }
+            }
+        }
+        endpoint._post = Mock(return_value=mock_response)
+
+        asset = endpoint.get(1)
+
+        assert isinstance(asset, Asset)
+        assert asset.id == 1
+
+    def test_rename_asset(self, endpoint):
+        """Test renaming an asset."""
+        mock_response = {
+            "data": {
+                "assets": {
+                    "renameAsset": {
+                        "responseResult": {"succeeded": True},
+                        "asset": {
+                            "id": 1,
+                            "filename": "newname.png",
+                            "ext": "png",
+                            "kind": "image",
+                            "mime": "image/png",
+                            "fileSize": 1024,
+                            "folderId": 0,
+                            "authorId": 1,
+                            "authorName": "Admin",
+                            "createdAt": "2024-01-01T00:00:00Z",
+                            "updatedAt": "2024-01-01T00:00:00Z",
+                        },
+                    }
+                }
+            }
+        }
+        endpoint._post = Mock(return_value=mock_response)
+
+        asset = endpoint.rename(1, "newname.png")
+
+        assert asset.filename == "newname.png"
+
+    def test_delete_asset(self, endpoint):
+        """Test deleting an asset."""
+        mock_response = {
+            "data": {
+                "assets": {
+                    "deleteAsset": {
+                        "responseResult": {"succeeded": True}
+                    }
+                }
+            }
+        }
+        endpoint._post = Mock(return_value=mock_response)
+
+        result = endpoint.delete(1)
+
+        assert result is True
+
+    def test_list_folders(self, endpoint):
+        """Test listing folders."""
+        mock_response = {
+            "data": {
+                "assets": {
+                    "folders": [
+                        {"id": 1, "slug": "documents", "name": "Documents"}
+                    ]
+                }
+            }
+        }
+        endpoint._post = Mock(return_value=mock_response)
+
+        folders = endpoint.list_folders()
+
+        assert len(folders) == 1
+        assert isinstance(folders[0], AssetFolder)
+        assert folders[0].slug == "documents"
+
+    def test_validation_errors(self, endpoint):
+        """Test validation errors."""
+        with pytest.raises(ValidationError):
+            endpoint.get(0)
+
+        with pytest.raises(ValidationError):
+            endpoint.delete(-1)
+
+        with pytest.raises(ValidationError):
+            endpoint.rename(1, "")