feat: add comprehensive client library and CI workflow

- Add UDFClient for simplified UDF server testing
- Implement professional test suite with isolated server instances
- Add comprehensive validation and error handling
- Support both positional and batch function calls
- Update CI workflow to include linting, formatting, and testing
- Test coverage across Python 3.9-3.12
- Fix code formatting and linting issues

Author: BohuTANG

.github/workflows/python.yml

@@ -20,20 +20,33 @@ concurrency:
 jobs:
   test:
     runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        python-version: ["3.9", "3.10", "3.11", "3.12"]
     steps:
       - uses: actions/checkout@v4
-      - name: Setup Python
+      - name: Setup Python ${{ matrix.python-version }}
         uses: actions/setup-python@v5
         with:
-          python-version: "3.12"
+          python-version: ${{ matrix.python-version }}
       - name: Install dependencies
         working-directory: python
-        run: pip install ruff
+        run: |
+          python -m pip install --upgrade pip
+          pip install -e .[lint,test]
+      - name: Lint with ruff
+        working-directory: python
+        run: |
+          ruff check .
       - name: Check format
         working-directory: python
         run: |
           ruff format --check .
-      - name: build
+      - name: Run tests
+        working-directory: python
+        run: |
+          python -m pytest tests/ -v --tb=short
+      - name: Build package
         working-directory: python
         run: |
           python -m pip install build

python/README_CLIENT.md

@@ -0,0 +1,121 @@
+# Databend UDF Client Library
+
+Simple Python client library for testing Databend UDF servers.
+
+## Installation
+
+```bash
+pip install databend-udf
+```
+
+## Quick Start
+
+```python
+from databend_udf import UDFClient, create_client
+
+# Create client (default: localhost:8815)
+client = create_client()
+
+# Or specify host/port
+client = UDFClient(host="localhost", port=8815)
+
+# Health check
+if client.health_check():
+    print("Server is running!")
+
+# Echo test
+result = client.echo("Hello, Databend!")
+print(result)  # "Hello, Databend!"
+
+# Call UDF function
+result = client.call_function("gcd", 48, 18)
+print(result[0])  # 6
+```
+
+## API Reference
+
+### UDFClient
+
+#### Methods
+
+- `__init__(host="localhost", port=8815)` - Create client
+- `health_check() -> bool` - Check server health
+- `echo(message: str) -> str` - Echo test message
+- `call_function(name, *args) -> List[Any]` - Call UDF with arguments
+- `call_function_batch(name, **kwargs) -> List[Any]` - Call UDF with batch data
+- `get_function_info(name) -> FlightInfo` - Get function schema
+- `list_functions() -> List[str]` - List available functions
+
+### Examples
+
+#### Single Value Calls
+
+```python
+client = create_client()
+
+# Numeric functions
+result = client.call_function("add_signed", 1, 2, 3, 4)
+print(result[0])  # 10
+
+# String functions
+result = client.call_function("split_and_join", "a,b,c", ",", "-")
+print(result[0])  # "a-b-c"
+
+# Array functions
+result = client.call_function("array_access", ["hello", "world"], 1)
+print(result[0])  # "hello"
+```
+
+#### Batch Calls
+
+```python
+client = create_client()
+
+# Process multiple values at once
+x_values = [48, 56, 72]
+y_values = [18, 21, 24]
+results = client.call_function_batch("gcd_batch", a=x_values, b=y_values)
+print(results)  # [6, 7, 24]
+```
+
+## Testing
+
+Run the example server:
+
+```bash
+cd python/example
+python server.py
+```
+
+In another terminal, run tests:
+
+```bash
+# Simple test
+python simple_test.py
+
+# Comprehensive test suite
+python client_test.py
+```
+
+## Error Handling
+
+```python
+try:
+    result = client.call_function("my_function", arg1, arg2)
+    print(result[0])
+except Exception as e:
+    print(f"Function call failed: {e}")
+```
+
+## Performance Testing
+
+The client supports testing concurrent I/O operations:
+
+```python
+# Sequential calls (slow)
+for i in range(10):
+    client.call_function("slow_function", i)
+
+# Batch call (fast with io_threads)
+client.call_function_batch("slow_function", a=list(range(10)))
+```

python/databend_udf/__init__.py

@@ -1 +1,4 @@
 from .udf import *  # noqa
+from .client import UDFClient, create_client
+
+__all__ = ["UDFClient", "create_client"]