De-emphasize notion of "default driver" (DBAPI)

Fixes: #6960

Even though a default driver still exists for
each dialect, remove most usages of `dialect://`
to encourage users to explicitly specify
`dialect+driver://`

Change-Id: I0ad42167582df509138fca64996bbb53e379b1af

9 files changed, 86 insertions, 53 deletions

diff --git a/test/dialect/mssql/test_deprecations.py b/test/dialect/mssql/test_deprecations.py
index aecb813fa..24625d65c 100644
--- a/test/dialect/mssql/test_deprecations.py
+++ b/test/dialect/mssql/test_deprecations.py
@@ -64,14 +64,14 @@ class LegacySchemaAliasingTest(fixtures.TestBase, AssertsCompiledSQL):
     @testing.combinations(
         (
             {
-                "sqlalchemy.url": "mssql://foodsn",
+                "sqlalchemy.url": "mssql+pyodbc://foodsn",
                 "sqlalchemy.legacy_schema_aliasing": "true",
             },
             True,
         ),
         (
             {
-                "sqlalchemy.url": "mssql://foodsn",
+                "sqlalchemy.url": "mssql+pyodbc://foodsn",
                 "sqlalchemy.legacy_schema_aliasing": "false",
             },
             False,
diff --git a/test/dialect/mssql/test_engine.py b/test/dialect/mssql/test_engine.py
index 5482e2616..e14fd164a 100644
--- a/test/dialect/mssql/test_engine.py
+++ b/test/dialect/mssql/test_engine.py
@@ -32,26 +32,27 @@ from sqlalchemy.testing.mock import Mock
 class ParseConnectTest(fixtures.TestBase):
     def test_pyodbc_connect_dsn_trusted(self):
         dialect = pyodbc.dialect()
-        u = url.make_url("mssql://mydsn")
+        u = url.make_url("mssql+pyodbc://mydsn")
         connection = dialect.create_connect_args(u)
         eq_([["dsn=mydsn;Trusted_Connection=Yes"], {}], connection)
 
     def test_pyodbc_connect_old_style_dsn_trusted(self):
         dialect = pyodbc.dialect()
-        u = url.make_url("mssql:///?dsn=mydsn")
+        u = url.make_url("mssql+pyodbc:///?dsn=mydsn")
         connection = dialect.create_connect_args(u)
         eq_([["dsn=mydsn;Trusted_Connection=Yes"], {}], connection)
 
     def test_pyodbc_connect_dsn_non_trusted(self):
         dialect = pyodbc.dialect()
-        u = url.make_url("mssql://username:password@mydsn")
+        u = url.make_url("mssql+pyodbc://username:password@mydsn")
         connection = dialect.create_connect_args(u)
         eq_([["dsn=mydsn;UID=username;PWD=password"], {}], connection)
 
     def test_pyodbc_connect_dsn_extra(self):
         dialect = pyodbc.dialect()
         u = url.make_url(
-            "mssql://username:password@mydsn/?LANGUAGE=us_" "english&foo=bar"
+            "mssql+pyodbc://username:password@mydsn/?LANGUAGE=us_"
+            "english&foo=bar"
         )
         connection = dialect.create_connect_args(u)
         dsn_string = connection[0][0]
@@ -61,7 +62,7 @@ class ParseConnectTest(fixtures.TestBase):
     def test_pyodbc_hostname(self):
         dialect = pyodbc.dialect()
         u = url.make_url(
-            "mssql://username:password@hostspec/database?driver=SQL+Server"
+            "mssql+pyodbc://username:password@hostspec/database?driver=SQL+Server"  # noqa
         )
         connection = dialect.create_connect_args(u)
         eq_(
@@ -84,7 +85,7 @@ class ParseConnectTest(fixtures.TestBase):
 
     def test_pyodbc_host_no_driver(self):
         dialect = pyodbc.dialect()
-        u = url.make_url("mssql://username:password@hostspec/database")
+        u = url.make_url("mssql+pyodbc://username:password@hostspec/database")
 
         def go():
             return dialect.create_connect_args(u)
@@ -111,7 +112,7 @@ class ParseConnectTest(fixtures.TestBase):
     def test_pyodbc_connect_comma_port(self):
         dialect = pyodbc.dialect()
         u = url.make_url(
-            "mssql://username:password@hostspec:12345/data"
+            "mssql+pyodbc://username:password@hostspec:12345/data"
             "base?driver=SQL Server"
         )
         connection = dialect.create_connect_args(u)
@@ -129,7 +130,7 @@ class ParseConnectTest(fixtures.TestBase):
     def test_pyodbc_connect_config_port(self):
         dialect = pyodbc.dialect()
         u = url.make_url(
-            "mssql://username:password@hostspec/database?p"
+            "mssql+pyodbc://username:password@hostspec/database?p"
             "ort=12345&driver=SQL+Server"
         )
         connection = dialect.create_connect_args(u)
@@ -147,7 +148,7 @@ class ParseConnectTest(fixtures.TestBase):
     def test_pyodbc_extra_connect(self):
         dialect = pyodbc.dialect()
         u = url.make_url(
-            "mssql://username:password@hostspec/database?L"
+            "mssql+pyodbc://username:password@hostspec/database?L"
             "ANGUAGE=us_english&foo=bar&driver=SQL+Server"
         )
         connection = dialect.create_connect_args(u)
@@ -186,7 +187,7 @@ class ParseConnectTest(fixtures.TestBase):
     def test_pyodbc_odbc_connect(self):
         dialect = pyodbc.dialect()
         u = url.make_url(
-            "mssql:///?odbc_connect=DRIVER%3D%7BSQL+Server"
+            "mssql+pyodbc:///?odbc_connect=DRIVER%3D%7BSQL+Server"
             "%7D%3BServer%3Dhostspec%3BDatabase%3Ddatabase"
             "%3BUID%3Dusername%3BPWD%3Dpassword"
         )
@@ -205,7 +206,7 @@ class ParseConnectTest(fixtures.TestBase):
     def test_pyodbc_odbc_connect_with_dsn(self):
         dialect = pyodbc.dialect()
         u = url.make_url(
-            "mssql:///?odbc_connect=dsn%3Dmydsn%3BDatabase"
+            "mssql+pyodbc:///?odbc_connect=dsn%3Dmydsn%3BDatabase"
             "%3Ddatabase%3BUID%3Dusername%3BPWD%3Dpassword"
         )
         connection = dialect.create_connect_args(u)
@@ -217,7 +218,7 @@ class ParseConnectTest(fixtures.TestBase):
     def test_pyodbc_odbc_connect_ignores_other_values(self):
         dialect = pyodbc.dialect()
         u = url.make_url(
-            "mssql://userdiff:passdiff@localhost/dbdiff?od"
+            "mssql+pyodbc://userdiff:passdiff@localhost/dbdiff?od"
             "bc_connect=DRIVER%3D%7BSQL+Server%7D%3BServer"
             "%3Dhostspec%3BDatabase%3Ddatabase%3BUID%3Duse"
             "rname%3BPWD%3Dpassword"
diff --git a/test/dialect/mysql/test_dialect.py b/test/dialect/mysql/test_dialect.py
index 834e1874c..9a0f2bc0d 100644
--- a/test/dialect/mysql/test_dialect.py
+++ b/test/dialect/mysql/test_dialect.py
@@ -202,7 +202,7 @@ class DialectTest(fixtures.TestBase):
         dialect = mysqldb.dialect()
         connect_args = dialect.create_connect_args(
             make_url(
-                "mysql://scott:tiger@localhost:3306/test"
+                "mysql+mysqldb://scott:tiger@localhost:3306/test"
                 "?%s=%s" % (kwarg, value)
             )
         )
@@ -262,7 +262,7 @@ class DialectTest(fixtures.TestBase):
     def test_random_arg(self):
         dialect = testing.db.dialect
         kw = dialect.create_connect_args(
-            make_url("mysql://u:p@host/db?foo=true")
+            make_url("mysql+mysqldb://u:p@host/db?foo=true")
         )[1]
         eq_(kw["foo"], "true")
 
@@ -303,7 +303,7 @@ class DialectTest(fixtures.TestBase):
 
 class ParseVersionTest(fixtures.TestBase):
     def test_mariadb_madness(self):
-        mysql_dialect = make_url("mysql://").get_dialect()()
+        mysql_dialect = make_url("mysql+mysqldb://").get_dialect()()
 
         is_(mysql_dialect.is_mariadb, False)
 
diff --git a/test/dialect/postgresql/test_dialect.py b/test/dialect/postgresql/test_dialect.py
index e7c4ebb7c..fe3700bbb 100644
--- a/test/dialect/postgresql/test_dialect.py
+++ b/test/dialect/postgresql/test_dialect.py
@@ -171,42 +171,44 @@ $$ LANGUAGE plpgsql;"""
 
     def test_psycopg2_empty_connection_string(self):
         dialect = psycopg2_dialect.dialect()
-        u = url.make_url("postgresql://")
+        u = url.make_url("postgresql+psycopg2://")
         cargs, cparams = dialect.create_connect_args(u)
         eq_(cargs, [""])
         eq_(cparams, {})
 
     def test_psycopg2_nonempty_connection_string(self):
         dialect = psycopg2_dialect.dialect()
-        u = url.make_url("postgresql://host")
+        u = url.make_url("postgresql+psycopg2://host")
         cargs, cparams = dialect.create_connect_args(u)
         eq_(cargs, [])
         eq_(cparams, {"host": "host"})
 
     def test_psycopg2_empty_connection_string_w_query_one(self):
         dialect = psycopg2_dialect.dialect()
-        u = url.make_url("postgresql:///?service=swh-log")
+        u = url.make_url("postgresql+psycopg2:///?service=swh-log")
         cargs, cparams = dialect.create_connect_args(u)
         eq_(cargs, [])
         eq_(cparams, {"service": "swh-log"})
 
     def test_psycopg2_empty_connection_string_w_query_two(self):
         dialect = psycopg2_dialect.dialect()
-        u = url.make_url("postgresql:///?any_random_thing=yes")
+        u = url.make_url("postgresql+psycopg2:///?any_random_thing=yes")
         cargs, cparams = dialect.create_connect_args(u)
         eq_(cargs, [])
         eq_(cparams, {"any_random_thing": "yes"})
 
     def test_psycopg2_nonempty_connection_string_w_query(self):
         dialect = psycopg2_dialect.dialect()
-        u = url.make_url("postgresql://somehost/?any_random_thing=yes")
+        u = url.make_url(
+            "postgresql+psycopg2://somehost/?any_random_thing=yes"
+        )
         cargs, cparams = dialect.create_connect_args(u)
         eq_(cargs, [])
         eq_(cparams, {"host": "somehost", "any_random_thing": "yes"})
 
     def test_psycopg2_nonempty_connection_string_w_query_two(self):
         dialect = psycopg2_dialect.dialect()
-        url_string = "postgresql://USER:PASS@/DB?host=hostA"
+        url_string = "postgresql+psycopg2://USER:PASS@/DB?host=hostA"
         u = url.make_url(url_string)
         cargs, cparams = dialect.create_connect_args(u)
         eq_(cargs, [])
@@ -215,7 +217,7 @@ $$ LANGUAGE plpgsql;"""
     def test_psycopg2_nonempty_connection_string_w_query_three(self):
         dialect = psycopg2_dialect.dialect()
         url_string = (
-            "postgresql://USER:PASS@/DB"
+            "postgresql+psycopg2://USER:PASS@/DB"
             "?host=hostA:portA&host=hostB&host=hostC"
         )
         u = url.make_url(url_string)
diff --git a/test/engine/test_deprecations.py b/test/engine/test_deprecations.py
index 6e7169d12..956524abd 100644
--- a/test/engine/test_deprecations.py
+++ b/test/engine/test_deprecations.py
@@ -278,7 +278,7 @@ class CreateEngineTest(fixtures.TestBase):
             "only argument accepted is 'mock'"
         ):
             e = create_engine(
-                "postgresql://", strategy="mock", executor=executor
+                "postgresql+psycopg2://", strategy="mock", executor=executor
             )
 
         assert isinstance(e, MockConnection)
@@ -292,7 +292,7 @@ class CreateEngineTest(fixtures.TestBase):
                 tsa.exc.ArgumentError,
                 "unknown strategy: 'threadlocal'",
                 create_engine,
-                "postgresql://",
+                "postgresql+psycopg2://",
                 strategy="threadlocal",
             )
 
@@ -302,7 +302,7 @@ class CreateEngineTest(fixtures.TestBase):
             "and no longer has any effect."
         ):
             create_engine(
-                "postgresql://",
+                "postgresql+psycopg2://",
                 empty_in_strategy="static",
                 module=Mock(),
                 _initialize=False,
diff --git a/test/engine/test_execute.py b/test/engine/test_execute.py
index afe95ba82..3b691ebc9 100644
--- a/test/engine/test_execute.py
+++ b/test/engine/test_execute.py
@@ -1161,7 +1161,7 @@ class MockStrategyTest(fixtures.TestBase):
         def dump(sql, *multiparams, **params):
             buf.write(util.text_type(sql.compile(dialect=engine.dialect)))
 
-        engine = create_mock_engine("postgresql://", executor=dump)
+        engine = create_mock_engine("postgresql+psycopg2://", executor=dump)
         return engine, buf
 
     def test_sequence_not_duped(self):
diff --git a/test/engine/test_parseconnect.py b/test/engine/test_parseconnect.py
index 044dc2cbd..f0a1dba4b 100644
--- a/test/engine/test_parseconnect.py
+++ b/test/engine/test_parseconnect.py
@@ -16,6 +16,7 @@ from sqlalchemy.testing import is_
 from sqlalchemy.testing import is_false
 from sqlalchemy.testing import is_true
 from sqlalchemy.testing import mock
+from sqlalchemy.testing import ne_
 from sqlalchemy.testing.assertions import expect_deprecated
 from sqlalchemy.testing.assertions import expect_raises_message
 from sqlalchemy.testing.mock import call
@@ -447,7 +448,7 @@ class CreateEngineTest(fixtures.TestBase):
     def test_connect_query(self):
         dbapi = MockDBAPI(foober="12", lala="18", fooz="somevalue")
         e = create_engine(
-            "postgresql://scott:tiger@somehost/test?foobe"
+            "postgresql+psycopg2://scott:tiger@somehost/test?foobe"
             "r=12&lala=18&fooz=somevalue",
             module=dbapi,
             _initialize=False,
@@ -459,7 +460,8 @@ class CreateEngineTest(fixtures.TestBase):
             foober=12, lala=18, hoho={"this": "dict"}, fooz="somevalue"
         )
         e = create_engine(
-            "postgresql://scott:tiger@somehost/test?fooz=" "somevalue",
+            "postgresql+psycopg2://scott:tiger@somehost/test?fooz="
+            "somevalue",
             connect_args={"foober": 12, "lala": 18, "hoho": {"this": "dict"}},
             module=dbapi,
             _initialize=False,
@@ -470,7 +472,7 @@ class CreateEngineTest(fixtures.TestBase):
         dbapi = mock_dbapi
 
         config = {
-            "sqlalchemy.url": "postgresql://scott:tiger@somehost/test"
+            "sqlalchemy.url": "postgresql+psycopg2://scott:tiger@somehost/test"
             "?fooz=somevalue",
             "sqlalchemy.pool_recycle": "50",
             "sqlalchemy.echo": "true",
@@ -479,7 +481,7 @@ class CreateEngineTest(fixtures.TestBase):
         e = engine_from_config(config, module=dbapi, _initialize=False)
         assert e.pool._recycle == 50
         assert e.url == url.make_url(
-            "postgresql://scott:tiger@somehost/test?foo" "z=somevalue"
+            "postgresql+psycopg2://scott:tiger@somehost/test?foo" "z=somevalue"
         )
         assert e.echo is True
 
@@ -487,7 +489,7 @@ class CreateEngineTest(fixtures.TestBase):
         dbapi = mock_dbapi
 
         config = {
-            "sqlalchemy.url": "postgresql://scott:tiger@somehost/test"
+            "sqlalchemy.url": "postgresql+psycopg2://scott:tiger@somehost/test"
             "?fooz=somevalue",
             "sqlalchemy.future": "true",
         }
@@ -498,7 +500,7 @@ class CreateEngineTest(fixtures.TestBase):
         dbapi = mock_dbapi
 
         config = {
-            "sqlalchemy.url": "postgresql://scott:tiger@somehost/test"
+            "sqlalchemy.url": "postgresql+psycopg2://scott:tiger@somehost/test"
             "?fooz=somevalue",
             "sqlalchemy.future": "false",
         }
@@ -519,7 +521,7 @@ class CreateEngineTest(fixtures.TestBase):
             ("none", pool.reset_none),
         ]:
             config = {
-                "sqlalchemy.url": "postgresql://scott:tiger@somehost/test",
+                "sqlalchemy.url": "postgresql+psycopg2://scott:tiger@somehost/test",  # noqa
                 "sqlalchemy.pool_reset_on_return": value,
             }
 
@@ -603,7 +605,10 @@ class CreateEngineTest(fixtures.TestBase):
         # module instead of psycopg
 
         e = create_engine(
-            "postgresql://", creator=connect, module=dbapi, _initialize=False
+            "postgresql+psycopg2://",
+            creator=connect,
+            module=dbapi,
+            _initialize=False,
         )
         e.connect()
 
@@ -612,7 +617,10 @@ class CreateEngineTest(fixtures.TestBase):
             foober=12, lala=18, hoho={"this": "dict"}, fooz="somevalue"
         )
         e = create_engine(
-            "postgresql://", pool_recycle=472, module=dbapi, _initialize=False
+            "postgresql+psycopg2://",
+            pool_recycle=472,
+            module=dbapi,
+            _initialize=False,
         )
         assert e.pool._recycle == 472
 
@@ -628,7 +636,7 @@ class CreateEngineTest(fixtures.TestBase):
             (False, pool.reset_none),
         ]:
             e = create_engine(
-                "postgresql://",
+                "postgresql+psycopg2://",
                 pool_reset_on_return=value,
                 module=dbapi,
                 _initialize=False,
@@ -638,7 +646,7 @@ class CreateEngineTest(fixtures.TestBase):
         assert_raises(
             exc.ArgumentError,
             create_engine,
-            "postgresql://",
+            "postgresql+psycopg2://",
             pool_reset_on_return="hi",
             module=dbapi,
             _initialize=False,
@@ -654,7 +662,7 @@ class CreateEngineTest(fixtures.TestBase):
         assert_raises(
             TypeError,
             create_engine,
-            "postgresql://",
+            "postgresql+psycopg2://",
             use_ansi=True,
             module=mock_dbapi,
         )
@@ -672,7 +680,7 @@ class CreateEngineTest(fixtures.TestBase):
         assert_raises(
             TypeError,
             create_engine,
-            "postgresql://",
+            "postgresql+psycopg2://",
             lala=5,
             module=mock_dbapi,
         )
@@ -695,25 +703,25 @@ class CreateEngineTest(fixtures.TestBase):
         """test the url attribute on ``Engine``."""
 
         e = create_engine(
-            "mysql://scott:tiger@localhost/test",
+            "mysql+mysqldb://scott:tiger@localhost/test",
             module=mock_dbapi,
             _initialize=False,
         )
-        u = url.make_url("mysql://scott:tiger@localhost/test")
+        u = url.make_url("mysql+mysqldb://scott:tiger@localhost/test")
         e2 = create_engine(u, module=mock_dbapi, _initialize=False)
-        assert e.url.drivername == e2.url.drivername == "mysql"
+        assert e.url.drivername == e2.url.drivername == "mysql+mysqldb"
         assert e.url.username == e2.url.username == "scott"
         assert e2.url is u
-        assert str(u) == "mysql://scott:tiger@localhost/test"
-        assert repr(u) == "mysql://scott:***@localhost/test"
-        assert repr(e) == "Engine(mysql://scott:***@localhost/test)"
-        assert repr(e2) == "Engine(mysql://scott:***@localhost/test)"
+        assert str(u) == "mysql+mysqldb://scott:tiger@localhost/test"
+        assert repr(u) == "mysql+mysqldb://scott:***@localhost/test"
+        assert repr(e) == "Engine(mysql+mysqldb://scott:***@localhost/test)"
+        assert repr(e2) == "Engine(mysql+mysqldb://scott:***@localhost/test)"
 
     def test_poolargs(self):
         """test that connection pool args make it thru"""
 
         e = create_engine(
-            "postgresql://",
+            "postgresql+psycopg2://",
             creator=None,
             pool_recycle=50,
             echo_pool=None,
@@ -725,7 +733,7 @@ class CreateEngineTest(fixtures.TestBase):
         # these args work for QueuePool
 
         e = create_engine(
-            "postgresql://",
+            "postgresql+psycopg2://",
             max_overflow=8,
             pool_timeout=60,
             poolclass=tsa.pool.QueuePool,
@@ -783,6 +791,26 @@ class CreateEngineTest(fixtures.TestBase):
         e.connect()
         eq_(sp.called, 1)
 
+    def test_default_driver(self):
+        successes = 0
+        for url_prefix, driver_name in [
+            ("mariadb://", "mysqldb"),
+            ("mssql://", "pyodbc"),
+            ("mysql://", "mysqldb"),
+            ("oracle://", "cx_oracle"),
+            ("postgresql://", "psycopg2"),
+            ("sqlite://", "pysqlite"),
+        ]:
+            try:
+                en = create_engine(url_prefix)
+                eq_(en.dialect.driver, driver_name)
+                successes += 1
+            except ModuleNotFoundError:
+                # not all test environments will have every driver installed
+                pass
+        # but we should at least find one
+        ne_(successes, 0, "No default drivers found.")
+
 
 class TestRegNewDBAPI(fixtures.TestBase):
     def test_register_base(self):
diff --git a/test/engine/test_reconnect.py b/test/engine/test_reconnect.py
index 0c7f86a62..c9894b0f2 100644
--- a/test/engine/test_reconnect.py
+++ b/test/engine/test_reconnect.py
@@ -166,7 +166,7 @@ class PrePingMockTest(fixtures.TestBase):
 
     def _pool_fixture(self, pre_ping, pool_kw=None):
         dialect = url.make_url(
-            "postgresql://foo:bar@localhost/test"
+            "postgresql+psycopg2://foo:bar@localhost/test"
         ).get_dialect()()
         dialect.dbapi = self.dbapi
         _pool = pool.QueuePool(
@@ -360,7 +360,7 @@ class MockReconnectTest(fixtures.TestBase):
         self.dbapi = MockDBAPI()
 
         self.db = testing_engine(
-            "postgresql://foo:bar@localhost/test",
+            "postgresql+psycopg2://foo:bar@localhost/test",
             options=dict(module=self.dbapi, _initialize=False),
         )
 
diff --git a/test/sql/test_deprecations.py b/test/sql/test_deprecations.py
index 22b743434..93e280d4e 100644
--- a/test/sql/test_deprecations.py
+++ b/test/sql/test_deprecations.py
@@ -178,7 +178,9 @@ class DeprecationWarningsTest(fixtures.TestBase, AssertsCompiledSQL):
             "The create_engine.convert_unicode parameter and "
             "corresponding dialect-level"
         ):
-            create_engine("mysql://", convert_unicode=True, module=mock.Mock())
+            create_engine(
+                "mysql+mysqldb://", convert_unicode=True, module=mock.Mock()
+            )
 
     def test_empty_and_or(self):
         with testing.expect_deprecated(