diff --git a/main_test.go b/main_test.go
new file mode 100644
index 0000000..97528dc
--- /dev/null
+++ b/main_test.go
@@ -0,0 +1,19 @@
+package main
+
+import "testing"
+
+func Do_getFiles(t *testing.T, parentDir, keys string, no int) {
+    files, err := getFiles(parentDir, keys)
+    if err != nil {
+        t.Fatalf("getFiles failed in %s by %s, %v", parentDir, keys, err)
+    }
+    if len(files) != no {
+        t.Fatalf("getFiles in %s by %s, expected %d, but got %d", parentDir, keys, no, len(files))
+    }
+}
+
+func Test_getFiles(t *testing.T) {
+    Do_getFiles(t, ".", "*.mod", 1)
+    Do_getFiles(t, ".", "*.mod *.sum", 2)
+    Do_getFiles(t, ".", "*.mod\n*.sum", 2)
+}