diff --git a/.github/workflows/main.yml b/.github/workflows/main.yml
index ea9b343..b63bb40 100644
--- a/.github/workflows/main.yml
+++ b/.github/workflows/main.yml
@@ -28,3 +28,29 @@ jobs:
           export PATH="/usr/share/miniconda/bin:$PATH"
           source activate black
           pyflakes spython/oci spython/image spython/instance spython/main
+
+  pytest:
+    runs-on: ubuntu-latest
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: [3.7, 3.8, 3.9]
+
+    steps:
+      - uses: actions/checkout@v2
+      - uses: eWaterCycle/setup-singularity@1631b12cf3878381179be0eab9624219bc12979e # v6 release
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v2
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install dependencies
+        run: |
+          sudo ln -s $SINGULARITY_ROOT/bin/singularity /usr/bin/
+          python -m pip install --upgrade pip
+          pip install pytest semver pytest-runner requests
+
+      - name: Run unit tests
+        run: |
+          pytest
diff --git a/spython/tests/test_client.py b/spython/tests/test_client.py
index 5a5e352..7b2aba5 100644
--- a/spython/tests/test_client.py
+++ b/spython/tests/test_client.py
@@ -43,12 +43,16 @@ def test_docker_pull(docker_container):
 def test_execute(docker_container):
     result = Client.execute(docker_container[1], "ls /")
     print(result)
+    if isinstance(result, list):
+        result = "".join(result)
     assert "tmp\nusr\nvar" in result
 
 
 def test_execute_with_return_code(docker_container):
     result = Client.execute(docker_container[1], "ls /", return_result=True)
     print(result)
+    if isinstance(result["message"], list):
+        result["message"] = "".join(result["message"])
     assert "tmp\nusr\nvar" in result["message"]
     assert result["return_code"] == 0
 
diff --git a/spython/tests/test_instances.py b/spython/tests/test_instances.py
index d2c9fa0..558ade9 100644
--- a/spython/tests/test_instances.py
+++ b/spython/tests/test_instances.py
@@ -9,6 +9,15 @@
 import pytest
 from spython.main import Client
 
+# name instance based on Python version in case running in parallel
+import sys
+
+version_string = "%s_%s_%s" % (
+    sys.version_info[0],
+    sys.version_info[1],
+    sys.version_info[2],
+)
+
 
 def test_instance_class():
     instance = Client.instance("docker://ubuntu", start=False)
@@ -28,13 +37,10 @@ def test_has_no_instances():
 
 class TestInstanceFuncs(object):
     @pytest.fixture(autouse=True)
-    def cleanup(self):
-        yield
-        Client.instance_stopall()
-
     def test_instance_cmds(self, docker_container):
         image = docker_container[1]
-        myinstance = Client.instance(image)
+        instance_name = "instance1_" + version_string
+        myinstance = Client.instance(image, name=instance_name)
         assert myinstance.get_uri().startswith("instance://")
 
         print("...Case 2: List instances")
@@ -58,12 +64,13 @@ def test_instance_cmds(self, docker_container):
         myinstance.stop()
         instances = Client.instances()
         assert instances == []
-        myinstance1 = Client.instance(image)
-        myinstance2 = Client.instance(image)
+        myinstance1 = Client.instance(image, name="instance1_" + version_string)
+        myinstance2 = Client.instance(image, name="instance2_" + version_string)
         assert myinstance1 is not None
         assert myinstance2 is not None
         instances = Client.instances()
         assert len(instances) == 2
-        Client.instance_stopall()
+        myinstance1.stop()
+        myinstance2.stop()
         instances = Client.instances()
         assert instances == []