ensure pysqlite dialect enumerates correct isolation levels

Fixed bug where the error message for SQLite invalid isolation level on the
pysqlite driver would fail to indicate that "AUTOCOMMIT" is one of the
valid isolation levels.

Change-Id: Icbceab9a28af6a560859761fa92320b5473269a9
References: #6959

5 files changed, 41 insertions, 2 deletions

diff --git a/doc/build/changelog/unreleased_14/sqlite_autocommit.rst b/doc/build/changelog/unreleased_14/sqlite_autocommit.rst
new file mode 100644
index 000000000..183e0eeed
--- /dev/null
+++ b/doc/build/changelog/unreleased_14/sqlite_autocommit.rst
@@ -0,0 +1,6 @@
+.. change::
+    :tags: bug, sqlite
+
+    Fixed bug where the error message for SQLite invalid isolation level on the
+    pysqlite driver would fail to indicate that "AUTOCOMMIT" is one of the
+    valid isolation levels.
diff --git a/lib/sqlalchemy/dialects/sqlite/base.py b/lib/sqlalchemy/dialects/sqlite/base.py
index dc5ebc3f0..c4a6bf8e9 100644
--- a/lib/sqlalchemy/dialects/sqlite/base.py
+++ b/lib/sqlalchemy/dialects/sqlite/base.py
@@ -1915,7 +1915,9 @@ class SQLiteDialect(default.DefaultDialect):
                 14,
             )
 
-    _isolation_lookup = {"READ UNCOMMITTED": 1, "SERIALIZABLE": 0}
+    _isolation_lookup = util.immutabledict(
+        {"READ UNCOMMITTED": 1, "SERIALIZABLE": 0}
+    )
 
     def set_isolation_level(self, connection, level):
         try:
@@ -1925,7 +1927,11 @@ class SQLiteDialect(default.DefaultDialect):
                 exc.ArgumentError(
                     "Invalid value '%s' for isolation_level. "
                     "Valid isolation levels for %s are %s"
-                    % (level, self.name, ", ".join(self._isolation_lookup))
+                    % (
+                        level,
+                        self.name,
+                        ", ".join(self._isolation_lookup),
+                    )
                 ),
                 replace_context=err,
             )
diff --git a/lib/sqlalchemy/dialects/sqlite/pysqlite.py b/lib/sqlalchemy/dialects/sqlite/pysqlite.py
index 96a5351da..0f96e8830 100644
--- a/lib/sqlalchemy/dialects/sqlite/pysqlite.py
+++ b/lib/sqlalchemy/dialects/sqlite/pysqlite.py
@@ -492,6 +492,12 @@ class SQLiteDialect_pysqlite(SQLiteDialect):
     def _get_server_version_info(self, connection):
         return self.dbapi.sqlite_version_info
 
+    _isolation_lookup = SQLiteDialect._isolation_lookup.union(
+        {
+            "AUTOCOMMIT": None,
+        }
+    )
+
     def set_isolation_level(self, connection, level):
         if hasattr(connection, "connection"):
             dbapi_connection = connection.connection
diff --git a/lib/sqlalchemy/testing/requirements.py b/lib/sqlalchemy/testing/requirements.py
index 742a9a1f8..e6e5db774 100644
--- a/lib/sqlalchemy/testing/requirements.py
+++ b/lib/sqlalchemy/testing/requirements.py
@@ -1227,6 +1227,10 @@ class SuiteRequirements(Requirements):
         return self.python36
 
     @property
+    def insert_order_dicts(self):
+        return self.python37
+
+    @property
     def python36(self):
         return exclusions.skip_if(
             lambda: sys.version_info < (3, 6),
diff --git a/test/dialect/test_sqlite.py b/test/dialect/test_sqlite.py
index b5ce291eb..ed0f11907 100644
--- a/test/dialect/test_sqlite.py
+++ b/test/dialect/test_sqlite.py
@@ -54,6 +54,7 @@ from sqlalchemy.testing import expect_warnings
 from sqlalchemy.testing import fixtures
 from sqlalchemy.testing import is_
 from sqlalchemy.testing import mock
+from sqlalchemy.testing.assertions import expect_raises_message
 from sqlalchemy.types import Boolean
 from sqlalchemy.types import Date
 from sqlalchemy.types import DateTime
@@ -596,6 +597,22 @@ class DialectTest(
                 )
             )
 
+    @testing.requires.insert_order_dicts
+    @testing.only_on("sqlite+pysqlite")
+    def test_isolation_level_message(self):
+        # needs to test that all three words are present and we also
+        # dont want to default all isolation level messages to use
+        # sorted(), so rely on python 3.7 for ordering of keywords
+        # in the message
+        with expect_raises_message(
+            exc.ArgumentError,
+            "Invalid value 'invalid' for "
+            "isolation_level. Valid isolation levels for "
+            "sqlite are READ UNCOMMITTED, SERIALIZABLE, AUTOCOMMIT",
+        ):
+            with testing.db.connect() as conn:
+                conn.execution_options(isolation_level="invalid")
+
     @testing.only_on("sqlite+pysqlcipher")
     def test_pysqlcipher_connects(self):
         """test #6586"""