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

3 files changed, 18 insertions, 2 deletions

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),