diff --git a/.pylintrc b/.pylintrc
index 4498033..03e3384 100644
--- a/.pylintrc
+++ b/.pylintrc
@@ -171,7 +171,7 @@ class-rgx=[A-Z_][a-zA-Z0-9]+$
 function-rgx=[a-z_][a-z0-9_]{2,30}$
 
 # Regular expression which should only match correct method names
-method-rgx=(test[A-Za-z0-9_]{2,30})|([a-z_][a-z0-9_]{2,30})$
+method-rgx=[a-z_][a-z0-9_]{2,30}$
 
 # Regular expression which should only match correct instance attribute names
 attr-rgx=[a-z_][a-z0-9_]{2,30}$
diff --git a/dfdewey/datastore/postgresql.py b/dfdewey/datastore/postgresql.py
index 921d1e8..d104092 100644
--- a/dfdewey/datastore/postgresql.py
+++ b/dfdewey/datastore/postgresql.py
@@ -125,7 +125,7 @@ class PostgresqlDataStore():
         WHERE table_schema = '{0:s}' AND table_name = '{1:s}'""".format(
             table_schema, table_name))
 
-    return self.cursor.fetchone()
+    return self.cursor.fetchone() is not None
 
   def value_exists(self, table_name, column_name, value):
     """Check if a value exists in a table.
@@ -143,4 +143,4 @@ class PostgresqlDataStore():
         SELECT 1 from {0:s}
         WHERE {1:s} = '{2:s}'""".format(table_name, column_name, value))
 
-    return self.cursor.fetchone()
+    return self.cursor.fetchone() is not None
diff --git a/dfdewey/datastore/postgresql_test.py b/dfdewey/datastore/postgresql_test.py
new file mode 100644
index 0000000..7ec56a9
--- /dev/null
+++ b/dfdewey/datastore/postgresql_test.py
@@ -0,0 +1,103 @@
+# -*- coding: utf-8 -*-
+# Copyright 2020 Google LLC
+#
+# Licensed under the Apache License, Version 2.0 (the "License");
+# you may not use this file except in compliance with the License.
+# You may obtain a copy of the License at
+#
+# https://www.apache.org/licenses/LICENSE-2.0
+#
+# Unless required by applicable law or agreed to in writing, software
+# distributed under the License is distributed on an "AS IS" BASIS,
+# WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+# See the License for the specific language governing permissions and
+# limitations under the License.
+"""Tests for PostgreSQL datastore."""
+
+import unittest
+import mock
+
+from dfdewey.datastore.postgresql import PostgresqlDataStore
+
+
+class PostgresqlTest(unittest.TestCase):
+  """Tests for PostgreSQL datastore."""
+
+  def _get_datastore(self):
+    """Get a mock postgresql datastore.
+
+    Returns:
+      Mock postgresql datastore.
+    """
+    with mock.patch('psycopg2.connect') as _:
+      db = PostgresqlDataStore(autocommit=True)
+      return db
+
+  @mock.patch('psycopg2.extras.execute_values')
+  def test_bulk_insert(self, _):
+    """Test bulk insert method."""
+    db = self._get_datastore()
+    rows = [(1, 1), (2, 2), (3, 3)]
+    db.bulk_insert('blocks (block, inum)', rows)
+
+  def test_execute(self):
+    """Test execute method."""
+    db = self._get_datastore()
+    command = (
+        'CREATE TABLE images (image_path TEXT, image_hash TEXT PRIMARY KEY)')
+    db.execute(command)
+
+  def test_query(self):
+    """Test query method."""
+    db = self._get_datastore()
+    query = 'SELECT filename FROM files WHERE inum = 0'
+    with mock.patch.object(db.cursor, 'fetchall', return_value=[('$MFT',)]):
+      results = db.query(query)
+
+    self.assertEqual(results, [('$MFT',)])
+
+  def test_query_single_row(self):
+    """Test query single row method."""
+    db = self._get_datastore()
+    query = (
+        'SELECT 1 from image_case WHERE image_hash = '
+        '\'d41d8cd98f00b204e9800998ecf8427e\'')
+    with mock.patch.object(db.cursor, 'fetchone', return_value=(1,)):
+      results = db.query_single_row(query)
+
+    self.assertEqual(results, (1,))
+
+  def test_switch_database(self):
+    """Test switch database method."""
+    db = self._get_datastore()
+    db.switch_database(db_name='dfdewey', autocommit=True)
+
+  def test_table_exists(self):
+    """Test table exists method."""
+    db = self._get_datastore()
+
+    with mock.patch.object(db.cursor, 'fetchone', return_value=(1,)):
+      result = db.table_exists('images')
+    self.assertEqual(result, True)
+
+    with mock.patch.object(db.cursor, 'fetchone', return_value=None):
+      result = db.table_exists('images')
+    self.assertEqual(result, False)
+
+  def test_value_exists(self):
+    """Test value exists method."""
+    db = self._get_datastore()
+
+    with mock.patch.object(db.cursor, 'fetchone', return_value=(1,)):
+      result = db.value_exists(
+          'images', 'image_hash', 'd41d8cd98f00b204e9800998ecf8427e')
+    self.assertEqual(result, True)
+
+    with mock.patch.object(db.cursor, 'fetchone', return_value=None):
+      result = db.value_exists(
+          'images', 'image_hash', 'd41d8cd98f00b204e9800998ecf8427e')
+    self.assertEqual(result, False)
+
+
+if __name__ == '__main__':
+  unittest.main()
diff --git a/dfdewey/utils/image.py b/dfdewey/utils/image.py
index a070d68..5f630ac 100644
--- a/dfdewey/utils/image.py
+++ b/dfdewey/utils/image.py
@@ -72,7 +72,7 @@ def check_tracking_database(tracking_db, image_path, image_hash, case):
     tracking_db.execute(
         """
         CREATE TABLE image_case (
-          case_id TEXT, image_hash TEXT REFERENCES images(image_hash), 
+          case_id TEXT, image_hash TEXT REFERENCES images(image_hash),
           PRIMARY KEY (case_id, image_hash))""")
   else:
     image_exists = tracking_db.value_exists('images', 'image_hash', image_hash)