diff --git a/tests.py b/tests.py
index be7c6b288ba46eee74b08e285e281e79994de51f..d68cc4e38a6bb00614f7f22d826c74f516365841 100644
--- a/tests.py
+++ b/tests.py
@@ -1,3 +1,5 @@
+"""Tests for mpsd-software-environment.py."""
+
 import importlib
 import os
 import shutil
@@ -10,7 +12,7 @@ mod = importlib.import_module("mpsd-software-environment")
 
 
 def test_os_chdir(tmp_path):
-    # create a temporary directory for testing
+    """Create a temporary directory for testing."""
     temp_dir = tmp_path / "test_os_chdir"
     temp_dir.mkdir()
 
@@ -26,11 +28,13 @@ def test_os_chdir(tmp_path):
 
 
 def test_prepare_environment(tmp_path):
-    # simulate running ./install-software-environment.py --release dev-23a \
-    #   --target-directory /tmp/test_prepare_env
-    # prepare_env is run when cmd is not specified, we can test cmd='prepare'
-    # and cmd=None to check both cases
+    """Simulate running preparation of environment.
 
+    Simulate running ./install-software-environment.py --release dev-23a \
+      --target-directory /tmp/test_prepare_env
+    prepare_env is run when cmd is not specified, we can test cmd='prepare'
+    and cmd=None to check both cases
+    """
     script_dir = tmp_path / "test_prepare_env"
     spack_environments = "spack-environments"
     mpsd_release_to_test = "dev-23a"
@@ -71,7 +75,10 @@ def test_prepare_environment(tmp_path):
 
 
 def test_setup_log_cmd(tmp_path):
-    # check that logs/install-software-environment.log is updated when the module is run
+    """Check that log is updated.
+
+    Check that logs/install-software-environment.log is updated when the module is run
+    """
     log_file = "install.log"
 
     script_dir = tmp_path / "test_prepare_env"
@@ -96,11 +103,13 @@ def test_setup_log_cmd(tmp_path):
 
 
 def test_install_environment(tmp_path):
-    # Test the installation part
-    # This is a long test, its handy to test this with print statements printed to
-    # stdout, use:
-    #   pytest -s
-    # Expect an Exception when wrong toolchains are provided
+    """Test the installation of a toolchain.
+
+    This is a long test, its handy to test this with print statements printed to
+    stdout, use:
+      pytest -s
+    Expect an Exception when wrong toolchains are provided
+    """
     with pytest.raises(Exception):
         mod.install_environment(
             mpsd_release="dev-23a",
@@ -213,6 +222,7 @@ def test_install_environment(tmp_path):
 
 
 def test_interface(tmp_path):
+    """Test other things (not implemented yet)."""
     pass
     # ensure that installing without toolchains only passes the available toolchains
     # check that the script branch and hash are correct when running the script