Test: Add web API test suite for knowledge base operations (#8254)

### What problem does this PR solve?

- Implement RAGFlowWebApiAuth class for web API authentication
- Add comprehensive test cases for KB CRUD operations
- Set up common fixtures and utilities in conftest.py
- Add helper functions in common.py for web API requests

The changes establish a complete testing framework for knowledge base
management via web API endpoints.

### Type of change

- [x] Add test case

test/testcases/test_web_api/conftest.py

@@ -0,0 +1,100 @@
+#
+#  Copyright 2025 The InfiniFlow Authors. All Rights Reserved.
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+#
+import pytest
+from common import (
+    batch_create_datasets,
+)
+from configs import HOST_ADDRESS, VERSION
+from libs.auth import RAGFlowWebApiAuth
+from pytest import FixtureRequest
+from ragflow_sdk import RAGFlow
+from utils.file_utils import (
+    create_docx_file,
+    create_eml_file,
+    create_excel_file,
+    create_html_file,
+    create_image_file,
+    create_json_file,
+    create_md_file,
+    create_pdf_file,
+    create_ppt_file,
+    create_txt_file,
+)
+
+
+@pytest.fixture
+def generate_test_files(request: FixtureRequest, tmp_path):
+    file_creators = {
+        "docx": (tmp_path / "ragflow_test.docx", create_docx_file),
+        "excel": (tmp_path / "ragflow_test.xlsx", create_excel_file),
+        "ppt": (tmp_path / "ragflow_test.pptx", create_ppt_file),
+        "image": (tmp_path / "ragflow_test.png", create_image_file),
+        "pdf": (tmp_path / "ragflow_test.pdf", create_pdf_file),
+        "txt": (tmp_path / "ragflow_test.txt", create_txt_file),
+        "md": (tmp_path / "ragflow_test.md", create_md_file),
+        "json": (tmp_path / "ragflow_test.json", create_json_file),
+        "eml": (tmp_path / "ragflow_test.eml", create_eml_file),
+        "html": (tmp_path / "ragflow_test.html", create_html_file),
+    }
+
+    files = {}
+    for file_type, (file_path, creator_func) in file_creators.items():
+        if request.param in ["", file_type]:
+            creator_func(file_path)
+            files[file_type] = file_path
+    return files
+
+
+@pytest.fixture(scope="class")
+def ragflow_tmp_dir(request, tmp_path_factory):
+    class_name = request.cls.__name__
+    return tmp_path_factory.mktemp(class_name)
+
+
+@pytest.fixture(scope="session")
+def WebApiAuth(auth):
+    return RAGFlowWebApiAuth(auth)
+
+
+@pytest.fixture(scope="session")
+def client(token: str) -> RAGFlow:
+    return RAGFlow(api_key=token, base_url=HOST_ADDRESS, version=VERSION)
+
+
+@pytest.fixture(scope="function")
+def clear_datasets(request: FixtureRequest, client: RAGFlow):
+    def cleanup():
+        client.delete_datasets(ids=None)
+
+    request.addfinalizer(cleanup)
+
+
+@pytest.fixture(scope="class")
+def add_dataset(request: FixtureRequest, client: RAGFlow, WebApiAuth: RAGFlowWebApiAuth) -> str:
+    def cleanup():
+        client.delete_datasets(ids=None)
+
+    request.addfinalizer(cleanup)
+    return batch_create_datasets(WebApiAuth, 1)[0]
+
+
+@pytest.fixture(scope="function")
+def add_dataset_func(request: FixtureRequest, client: RAGFlow, WebApiAuth: RAGFlowWebApiAuth) -> str:
+    def cleanup():
+        client.delete_datasets(ids=None)
+
+    request.addfinalizer(cleanup)
+    return batch_create_datasets(WebApiAuth, 1)[0]