diff --git a/cluster/tools/kartongips/cmd/completion_test.go b/cluster/tools/kartongips/cmd/completion_test.go
new file mode 100644
index 0000000..1334aa2
--- /dev/null
+++ b/cluster/tools/kartongips/cmd/completion_test.go
@@ -0,0 +1,19 @@
+package cmd
+
+import (
+	"testing"
+)
+
+func TestGuessShell(t *testing.T) {
+	t.Parallel()
+
+	for _, test := range [][]string{
+		{"/bin/bash", "bash"},
+		{"/usr/bin/zsh", "zsh"},
+		{"/usr/bin/zsh5", "zsh"},
+	} {
+		if result := guessShell(test[0]); result != test[1] {
+			t.Errorf("Guessed %q instead of %q from %q", result, test[1], test[0])
+		}
+	}
+}