FEAT: Pytests for Dependencies (#139)

### ADO Work Item Reference  
<!-- Insert your ADO Work Item ID below (e.g. AB#37452) -->
>
[AB#37995](https://sqlclientdrivers.visualstudio.com/c6d89619-62de-46a0-8b46-70b92a84d85e/_workitems/edit/37995)
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### Summary   
<!-- Insert your Copilot Generated Summary below -->  
This pull request introduces significant updates to the `mssql_python`
package, focusing on architecture-specific dependency handling,
documentation improvements, and comprehensive testing. Key changes
include enhancements to the README for better clarity on
platform-specific builds, removal of unused imports, and the addition of
a new test file to validate dependencies across platforms.

### Documentation Updates:
*
[`mssql_python/pybind/README.md`](diffhunk://#diff-1429930017ef4a5b84d9331206c1ac47e546427b914986e531e3f04e45f4bb31L3-R22):
Expanded documentation to include platform-specific architecture
handling, runtime loading mechanisms, and dependency summaries for
Windows, macOS, and Linux. Added detailed directory structure and naming
conventions for Python extension modules.
[[1]](diffhunk://#diff-1429930017ef4a5b84d9331206c1ac47e546427b914986e531e3f04e45f4bb31L3-R22)
[[2]](diffhunk://#diff-1429930017ef4a5b84d9331206c1ac47e546427b914986e531e3f04e45f4bb31L28-R47)
[[3]](diffhunk://#diff-1429930017ef4a5b84d9331206c1ac47e546427b914986e531e3f04e45f4bb31L62-R167)

### Code Cleanup:
*
[`tests/conftest.py`](diffhunk://#diff-e52e4ddd58b7ef887ab03c04116e676f6280b824ab7469d5d3080e5cba4f2128L12-R12):
Removed unused `ddbc_bindings` import to streamline the test
configuration file.

### Testing Enhancements:
*
[`tests/test_000_dependencies.py`](diffhunk://#diff-e489a2a29f29954dcd0b17a34b15e53ee2aa4fa1def0a5a466bcee81df59ddf0R1-R352):
Added a new test file to validate platform-specific dependencies,
architecture normalization, and runtime compatibility. Includes helper
functions for detecting Linux distributions and verifying dependency
files and Python extension modules.

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Author: bewithgaurav

mssql_python/pybind/README.md

@@ -1,6 +1,25 @@
 # Build Instructions for Developers
 
-This README provides instructions to build the DDBC Bindings PYD for your system (supports Windows x64 and arm64).
+This README provides instructions to build the DDBC Bindings for your system and documents the platform-specific dependencies.
+
+## **Key Architecture Handling**
+
+1. **Architecture Normalization** (from `mssql_python/ddbc_bindings.py`):
+   - Windows: `win64/amd64/x64` → `x64`, `win32/x86` → `x86`, `arm64` → `arm64`
+   - macOS: Always uses `universal2` for distribution
+   - Linux: `x64/amd64` → `x86_64`, `arm64/aarch64` → `arm64`
+
+2. **Build System Support**:
+   - CMake handles universal binaries for macOS (`arm64;x86_64`)
+   - Windows `mssql_python/pybind/build.bat` supports x64, x86, and ARM64
+   - Linux builds are distribution-aware (Debian/Ubuntu vs RHEL)
+
+3. **Runtime Loading**:
+   - `LoadDriverLibrary()` in `mssql_python/pybind/ddbc_bindings.cpp` handles platform-specific loading
+   - Windows uses `LoadLibraryW()`
+   - macOS/Linux uses `dlopen()`
+
+---
 
 ## Building on Windows
 > Supporting Windows x64 & ARM64 only
@@ -25,7 +44,7 @@ This README provides instructions to build the DDBC Bindings PYD for your system
 - The script will:
     - Clean up existing build directories
     - Detect VS Build Tools Installation, and start compilation for your Python version and Windows architecture
-    - Compile `ddbc_bindings.cpp` using CMake and create properly versioned PYD file (`ddbc_bindings.cp313-amd64.pyd`)
+    - Compile `mssql_python/pybind/ddbc_bindings.cpp` using CMake and create properly versioned PYD file (`ddbc_bindings.cp313-amd64.pyd`)
     - Move the built PYD file to the parent `mssql_python` directory
 
 ## Building on MacOS
@@ -59,6 +78,90 @@ This README provides instructions to build the DDBC Bindings PYD for your system
    - Clean any existing build artifacts
    - Detect system architecture
    - Configure CMake with appropriate include/library paths
-   - Compile `ddbc_bindings.cpp` using CMake
+   - Compile `mssql_python/pybind/ddbc_bindings.cpp` using CMake
    - Generate the `.so` file (e.g., `ddbc_bindings.cp313-universal2.so`)
    - Copy the output SO file to the parent `mssql_python` directory
+
+## Architecture Dependencies Summary
+
+### **Directory Structure**
+```
+mssql_python/
+├── libs/
+│   ├── windows/
+│   │   ├── x64/
+│   │   ├── x86/
+│   │   └── arm64/
+│   ├── macos/
+│   │   ├── arm64/lib/
+│   │   └── x86_64/lib/
+│   └── linux/
+│       ├── debian_ubuntu/
+│       │   ├── x86_64/lib/
+│       │   └── arm64/lib/
+│       └── rhel/
+│           ├── x86_64/lib/
+│           └── arm64/lib/
+└── ddbc_bindings.cp{python_version}-{architecture}.{extension}
+```
+
+### **Windows (.dll files)**
+Windows builds depend on these DLLs for different architectures:
+
+**x64 (amd64):**
+- `msodbcsql18.dll` - Main driver
+- `msodbcdiag18.dll` - Diagnostic library
+- `mssql-auth.dll` - Authentication library (for Entra ID)
+- `vcredist/msvcp140.dll` - Visual C++ runtime (from vcredist)
+
+**x86 (win32):**
+- `msodbcsql18.dll` - Main driver
+- `msodbcdiag18.dll` - Diagnostic library  
+- `mssql-auth.dll` - Authentication library
+- `vcredist/msvcp140.dll` - Visual C++ runtime (from vcredist)
+
+**ARM64:**
+- `msodbcsql18.dll` - Main driver
+- `msodbcdiag18.dll` - Diagnostic library
+- `mssql-auth.dll` - Authentication library
+- `vcredist/msvcp140.dll` - Visual C++ runtime (from vcredist)
+
+### **macOS (.dylib files)**
+macOS builds use universal2 binaries and depend on:
+
+**Packaged Dependencies (arm64 & x86_64):**
+- `libmsodbcsql.18.dylib` - Main driver
+- `libodbcinst.2.dylib` - Installer library
+
+### **Linux (.so files)**
+Linux builds support multiple distributions:
+
+**Debian/Ubuntu x86_64:**
+- `libmsodbcsql-18.5.so.1.1` - Main driver
+- `libodbcinst.so.2` - Installer library
+
+**Debian/Ubuntu ARM64:**
+- `libmsodbcsql-18.5.so.1.1` - Main driver
+- `libodbcinst.so.2` - Installer library
+
+**RHEL/CentOS x86_64:**
+- `libmsodbcsql-18.5.so.1.1` - Main driver
+- `libodbcinst.so.2` - Installer library
+
+**RHEL/CentOS ARM64:**
+- `libmsodbcsql-18.5.so.1.1` - Main driver
+- `libodbcinst.so.2` - Installer library
+
+## **Python Extension Modules**
+Your build system generates architecture-specific Python extension modules:
+
+**Naming Convention:** `ddbc_bindings.cp{python_version}-{architecture}.{extension}`
+
+Examples:
+- Windows x64: `ddbc_bindings.cp311-amd64.pyd`
+- Windows x86: `ddbc_bindings.cp311-win32.pyd`
+- Windows ARM64: `ddbc_bindings.cp311-arm64.pyd`
+- macOS Universal: `ddbc_bindings.cp311-universal2.so`
+- Linux x86_64: `ddbc_bindings.cp311-x86_64.so`
+- Linux ARM64: `ddbc_bindings.cp311-arm64.so`
+

tests/conftest.py

@@ -9,7 +9,7 @@
 
 import pytest
 import os
-from mssql_python import connect, ddbc_bindings
+from mssql_python import connect
 import time
 
 def pytest_configure(config):