diff --git a/data_diff/databases/database_types.py b/data_diff/databases/database_types.py
index 1570fb3c..22691d40 100644
--- a/data_diff/databases/database_types.py
+++ b/data_diff/databases/database_types.py
@@ -40,9 +40,11 @@ class NumericType(ColType):
     # 'precision' signifies how many fractional digits (after the dot) we want to compare
     precision: int
 
+
 class FractionalType(NumericType):
     pass
 
+
 class Float(FractionalType):
     pass
 
diff --git a/data_diff/diff_tables.py b/data_diff/diff_tables.py
index 49c03fd9..b9526e8d 100644
--- a/data_diff/diff_tables.py
+++ b/data_diff/diff_tables.py
@@ -96,7 +96,7 @@ def _update_column(self):
 
     def _quote_column(self, c):
         if self._schema:
-            c = self._schema.get_key(c)     # Get the actual name. Might be case-insensitive.
+            c = self._schema.get_key(c)  # Get the actual name. Might be case-insensitive.
         return self.database.quote(c)
 
     def with_schema(self) -> "TableSegment":
diff --git a/tests/test_api.py b/tests/test_api.py
index e9e56f67..46658479 100644
--- a/tests/test_api.py
+++ b/tests/test_api.py
@@ -8,14 +8,8 @@
 
 
 class TestApi(unittest.TestCase):
-    @classmethod
-    def setUpClass(cls):
-        # Avoid leaking connections that require waiting for the GC, which can
-        # cause deadlocks for table-level modifications.
-        cls.preql = preql.Preql(TEST_MYSQL_CONN_STRING)
-
     def setUp(self) -> None:
-        # self.preql = preql.Preql(TEST_MYSQL_CONN_STRING)
+        self.preql = preql.Preql(TEST_MYSQL_CONN_STRING)
         self.preql(
             r"""
             table test_api {
diff --git a/tests/test_database_types.py b/tests/test_database_types.py
index 89832ed6..09ea2484 100644
--- a/tests/test_database_types.py
+++ b/tests/test_database_types.py
@@ -3,7 +3,7 @@
 import time
 import re
 import math
-import datetime
+from datetime import datetime, timedelta
 from decimal import Decimal
 from parameterized import parameterized
 
@@ -52,12 +52,12 @@ def __next__(self) -> str:
 
 class DateTimeFaker:
     MANUAL_FAKES = [
-        datetime.datetime.fromisoformat("2020-01-01 15:10:10"),
-        datetime.datetime.fromisoformat("2020-02-01 09:09:09"),
-        datetime.datetime.fromisoformat("2022-03-01 15:10:01.139"),
-        datetime.datetime.fromisoformat("2022-04-01 15:10:02.020409"),
-        datetime.datetime.fromisoformat("2022-05-01 15:10:03.003030"),
-        datetime.datetime.fromisoformat("2022-06-01 15:10:05.009900"),
+        datetime.fromisoformat("2020-01-01 15:10:10"),
+        datetime.fromisoformat("2020-02-01 09:09:09"),
+        datetime.fromisoformat("2022-03-01 15:10:01.139"),
+        datetime.fromisoformat("2022-04-01 15:10:02.020409"),
+        datetime.fromisoformat("2022-05-01 15:10:03.003030"),
+        datetime.fromisoformat("2022-06-01 15:10:05.009900"),
     ]
 
     def __init__(self, max):
@@ -65,20 +65,20 @@ def __init__(self, max):
 
     def __iter__(self):
         iter = DateTimeFaker(self.max)
-        iter.prev = datetime.datetime(2000, 1, 1, 0, 0, 0, 0)
+        iter.prev = datetime(2000, 1, 1, 0, 0, 0, 0)
         iter.i = 0
         return iter
 
     def __len__(self):
         return self.max
 
-    def __next__(self) -> datetime.datetime:
+    def __next__(self) -> datetime:
         if self.i < len(self.MANUAL_FAKES):
             fake = self.MANUAL_FAKES[self.i]
             self.i += 1
             return fake
         elif self.i < self.max:
-            self.prev = self.prev + datetime.timedelta(seconds=3, microseconds=571)
+            self.prev = self.prev + timedelta(seconds=3, microseconds=571)
             self.i += 1
             return self.prev
         else:
@@ -373,7 +373,7 @@ def _insert_to_table(conn, table, values):
         for j, sample in values:
             if isinstance(sample, (float, Decimal, int)):
                 value = str(sample)
-            elif isinstance(sample, datetime.datetime) and isinstance(conn, db.Presto):
+            elif isinstance(sample, datetime) and isinstance(conn, db.Presto):
                 value = f"timestamp '{sample}'"
             else:
                 value = f"'{sample}'"
@@ -422,6 +422,11 @@ def test_types(self, source_db, target_db, source_type, target_type, type_catego
         _insert_to_table(src_conn, src_table, enumerate(sample_values, 1))
 
         values_in_source = PaginatedTable(src_table, src_conn)
+        if source_db is db.Presto:
+            if source_type.startswith("decimal"):
+                values_in_source = [(a, Decimal(b)) for a, b in values_in_source]
+            elif source_type.startswith("timestamp"):
+                values_in_source = [(a, datetime.fromisoformat(b.rstrip(" UTC"))) for a, b in values_in_source]
 
         _drop_table_if_exists(dst_conn, dst_table)
         dst_conn.query(f"CREATE TABLE {dst_table}(id int, col {target_type})", None)