diff --git a/.stestr.conf b/.stestr.conf
index f21840bb584b..cd26f5dfae1a 100644
--- a/.stestr.conf
+++ b/.stestr.conf
@@ -1,3 +1,2 @@
 [DEFAULT]
 test_path=./test/python
-group_regex=([^\.]*\.)*
diff --git a/test/python/test_user_config.py b/test/python/test_user_config.py
index a21f70942cf9..d37bc52d0d5c 100644
--- a/test/python/test_user_config.py
+++ b/test/python/test_user_config.py
@@ -13,6 +13,7 @@
 # pylint: disable=missing-docstring
 
 import os
+from uuid import uuid4
 
 from qiskit import exceptions
 from qiskit.test import QiskitTestCase
@@ -20,9 +21,9 @@
 
 
 class TestUserConfig(QiskitTestCase):
-    @classmethod
-    def setUpClass(cls):
-        cls.file_path = "temp.txt"
+    def setUp(self):
+        super().setUp()
+        self.file_path = "test_%s.conf" % uuid4()
 
     def test_empty_file_read(self):
         config = user_config.UserConfig(self.file_path)
diff --git a/test/python/visualization/test_gate_map.py b/test/python/visualization/test_gate_map.py
index be687a18c16d..c13e1c05e4dc 100644
--- a/test/python/visualization/test_gate_map.py
+++ b/test/python/visualization/test_gate_map.py
@@ -12,8 +12,9 @@
 
 """A test for visualizing device coupling maps"""
 import unittest
-import os
 
+from io import BytesIO
+from PIL import Image
 from ddt import ddt, data
 from qiskit.test.mock import FakeProvider
 from qiskit.test import QiskitTestCase
@@ -45,11 +46,12 @@ def test_plot_gate_map(self, backend):
         """tests plotting of gate map of a device (20 qubit, 16 qubit, 14 qubit and 5 qubit)"""
         n = backend.configuration().n_qubits
         img_ref = path_to_diagram_reference(str(n) + "bit_quantum_computer.png")
-        filename = "temp.png"
         fig = plot_gate_map(backend)
-        fig.savefig(filename)
-        self.assertImagesAreEqual(filename, img_ref, 0.2)
-        os.remove(filename)
+        with BytesIO() as img_buffer:
+            fig.savefig(img_buffer, format="png")
+            img_buffer.seek(0)
+            self.assertImagesAreEqual(Image.open(img_buffer), img_ref, 0.2)
+        plt.close(fig)
 
     @data(*backends)
     @unittest.skipIf(not HAS_MATPLOTLIB, "matplotlib not available.")
@@ -62,11 +64,12 @@ def test_plot_circuit_layout(self, backend):
         circuit._layout.add_register(qr)
         n = backend.configuration().n_qubits
         img_ref = path_to_diagram_reference(str(n) + "_plot_circuit_layout.png")
-        filename = str(n) + "_plot_circuit_layout_result.png"
         fig = plot_circuit_layout(circuit, backend)
-        fig.savefig(filename)
-        self.assertImagesAreEqual(filename, img_ref, 0.1)
-        os.remove(filename)
+        with BytesIO() as img_buffer:
+            fig.savefig(img_buffer, format="png")
+            img_buffer.seek(0)
+            self.assertImagesAreEqual(Image.open(img_buffer), img_ref, 0.1)
+        plt.close(fig)
 
 
 @unittest.skipIf(not HAS_MATPLOTLIB, "matplotlib not available.")