Add deprectaion warnings for trubodbc and pyodbc (#441)

CHANGELOG.rst

@@ -5,6 +5,7 @@ Unreleased
 
 🔧 Changed
 -----------
+- Added deprecation warnings for pyodbc and trubodbc dialects
 - Made websockets the default way to use sqlalchemy with exasol
 - Made pydobc an optional dependency
 

pyproject.toml

@@ -110,6 +110,7 @@ addopts = "--tb native -v -r fxX"
 filterwarnings = [
     "error::DeprecationWarning",
     "ignore::DeprecationWarning:sqlalchemy.testing.plugin.*",
+    "ignore::DeprecationWarning:sqlalchemy_exasol.*",
 ]
 
 [tool.black]

sqlalchemy_exasol/pyodbc.py

@@ -9,6 +9,7 @@
 import logging
 import re
 import sys
+from warnings import warn
 
 from packaging import version
 from sqlalchemy import sql
@@ -20,6 +21,7 @@
     EXADialect,
     EXAExecutionContext,
 )
+from sqlalchemy_exasol.warnings import SqlaExasolDeprecationWarning
 
 logger = logging.getLogger("sqlalchemy_exasol")
 
@@ -30,6 +32,11 @@ class EXADialect_pyodbc(EXADialect, PyODBCConnector):
     driver_version = None
 
     def __init__(self, **kw):
+        message = (
+            "'pyodbc' support in 'sqlalchemy_exasol' is deprecated and will be removed. "
+            "Please switch to the websocket driver. See documentation for details."
+        )
+        warn(message, SqlaExasolDeprecationWarning)
         super().__init__(**kw)
 
     def get_driver_version(self, connection):

sqlalchemy_exasol/turbodbc.py

@@ -1,9 +1,11 @@
 import decimal
+from warnings import warn
 
 from sqlalchemy import types as sqltypes
 from sqlalchemy import util
 
 from sqlalchemy_exasol.base import EXADialect
+from sqlalchemy_exasol.warnings import SqlaExasolDeprecationWarning
 
 DEFAULT_CONNECTION_PARAMS = {
     # always enable efficient conversion to Python types:
@@ -72,6 +74,14 @@ class EXADialect_turbodbc(EXADialect):
 
     colspecs = {sqltypes.Numeric: _ExaDecimal, sqltypes.Integer: _ExaInteger}
 
+    def __init__(self, **kw):
+        message = (
+            "'turbodbc' support in 'sqlalchemy_exasol' is deprecated and will be removed. "
+            "Please switch to the websocket driver. See documentation for details."
+        )
+        warn(message, SqlaExasolDeprecationWarning)
+        super().__init__(**kw)
+
     @classmethod
     def dbapi(cls):
         return __import__("turbodbc")

sqlalchemy_exasol/warnings.py

@@ -0,0 +1,6 @@
+class SqlaExasolWarning(UserWarning):
+    """Base class for all warnings emited by sqlalchemy_exasol."""
+
+
+class SqlaExasolDeprecationWarning(SqlaExasolWarning, DeprecationWarning):
+    """Warning class for features that will be removed in future versions."""

test/unit/exasol/test_deprectation_warnings.py

@@ -0,0 +1,12 @@
+import pytest
+
+from sqlalchemy_exasol.pyodbc import EXADialect_pyodbc
+from sqlalchemy_exasol.turbodbc import EXADialect_turbodbc
+
+
+@pytest.mark.parametrize(
+    "klass,kwargs", [(EXADialect_pyodbc, {}), (EXADialect_turbodbc, {})]
+)
+def test_deprectation_warnings(klass, kwargs):
+    with pytest.deprecated_call():
+        _ = EXADialect_pyodbc(**kwargs)