diff --git a/spin/tests/test_build_cmds.py b/spin/tests/test_build_cmds.py
index f802618..dae17e5 100644
--- a/spin/tests/test_build_cmds.py
+++ b/spin/tests/test_build_cmds.py
@@ -4,41 +4,10 @@
 import tempfile
 from pathlib import Path
 
-import pytest
+from testutil import skip_on_windows, skip_unless_linux, spin, stdout
 
-import spin as libspin
 from spin.cmds.util import run
 
-skip_on_windows = pytest.mark.skipif(
-    sys.platform.startswith("win"), reason="Skipped; platform is Windows"
-)
-
-on_linux = pytest.mark.skipif(
-    not sys.platform.startswith("linux"), reason="Skipped; platform not Linux"
-)
-
-
-def spin(*args, **user_kwargs):
-    default_kwargs = {
-        "stdout": subprocess.PIPE,
-        "stderr": subprocess.PIPE,
-        "sys_exit": True,
-    }
-    return run(["spin"] + list(args), **{**default_kwargs, **user_kwargs})
-
-
-def stdout(p):
-    return p.stdout.decode("utf-8").strip()
-
-
-def stderr(p):
-    return p.stderr.decode("utf-8").strip()
-
-
-def test_get_version():
-    p = spin("--version")
-    assert stdout(p) == f"spin {libspin.__version__}"
-
 
 def test_basic_build():
     """Does the package build?"""
@@ -145,7 +114,7 @@ def test_spin_install():
             run(["pip", "uninstall", "-y", "--quiet", "example_pkg"])
 
 
-@on_linux
+@skip_unless_linux
 def test_gdb():
     p = spin(
         "gdb",
diff --git a/spin/tests/test_cli.py b/spin/tests/test_cli.py
new file mode 100644
index 0000000..21f5c65
--- /dev/null
+++ b/spin/tests/test_cli.py
@@ -0,0 +1,17 @@
+from testutil import spin, stdout
+
+import spin as libspin
+
+
+def test_get_version():
+    p = spin("--version")
+    assert stdout(p) == f"spin {libspin.__version__}"
+
+
+def test_arg_override():
+    p = spin("example")
+    assert "--test is: default override" in stdout(p)
+    assert "Default kwd is: 3" in stdout(p)
+
+    p = spin("example", "-t", 6)
+    assert "--test is: 6" in stdout(p)
diff --git a/spin/tests/testutil.py b/spin/tests/testutil.py
new file mode 100644
index 0000000..5595e2d
--- /dev/null
+++ b/spin/tests/testutil.py
@@ -0,0 +1,32 @@
+import subprocess
+import sys
+
+import pytest
+
+from spin.cmds.util import run
+
+skip_on_windows = pytest.mark.skipif(
+    sys.platform.startswith("win"), reason="Skipped; platform is Windows"
+)
+
+skip_unless_linux = pytest.mark.skipif(
+    not sys.platform.startswith("linux"), reason="Skipped; platform not Linux"
+)
+
+
+def spin(*args, **user_kwargs):
+    args = (str(el) for el in args)
+    default_kwargs = {
+        "stdout": subprocess.PIPE,
+        "stderr": subprocess.PIPE,
+        "sys_exit": True,
+    }
+    return run(["spin"] + list(args), **{**default_kwargs, **user_kwargs})
+
+
+def stdout(p):
+    return p.stdout.decode("utf-8").strip()
+
+
+def stderr(p):
+    return p.stderr.decode("utf-8").strip()
diff --git a/spin/tests/util.py b/spin/tests/util.py
deleted file mode 100644
index 09a3d63..0000000
--- a/spin/tests/util.py
+++ /dev/null
@@ -1,28 +0,0 @@
-import os
-import subprocess
-
-from spin.cmds import util
-
-PKG_NAME = "example_pkg"
-
-
-def assert_cmd(cmd, *args, **kwargs) -> str:
-    cwd = os.getcwd()
-    p = util.run(
-        cmd,
-        *args,
-        cwd=PKG_NAME,
-        replace=False,
-        sys_exit=False,
-        output=False,
-        echo=True,
-        stdout=subprocess.PIPE,
-        stderr=subprocess.PIPE,
-        **kwargs,
-    )
-    os.chdir(cwd)
-    stdout = p.stdout.decode("utf-8").strip()
-    if not p.returncode == 0:
-        print(stdout)
-        raise AssertionError(f"[{cmd}] failed with exit code {p.returncode}")
-    return p