Merge pull request #13 from dorayakikun/refactor-concat

refactor: Refactor `concat` implementation

Author: tadashi-aikawa

command.go

@@ -17,11 +17,7 @@ import (
 const gowlSite = "gowl.site"
 
 func concat(elm string, elms []string) []string {
-	rets := []string{elm}
-	for _, x := range elms {
-		rets = append(rets, x)
-	}
-	return rets
+	return append(append([]string(nil), elm), elms...)
 }
 
 func toSelection(r Repository) string {

command_test.go

@@ -0,0 +1,41 @@
+package main
+
+import "testing"
+
+func TestConcat(t *testing.T) {
+	cases := []struct{
+		elm string
+		elms []string
+		want []string
+	} {
+		{
+			elm: "",
+			elms: []string(nil),
+			want: []string{""},
+		},
+		{
+			elm: "owl",
+			elms: []string{"fox"},
+			want: []string{"owl", "fox"},
+		},
+		{
+			elm: "owl",
+			elms: []string{"fox", "raccoon"},
+			want: []string{"owl", "fox", "raccoon"},
+		},
+	}
+
+	for _, c := range cases {
+		ret := concat(c.elm, c.elms)
+
+		if len(ret) != len(c.want) {
+			t.Fatalf("size unmatch r: %q want: %q\n", ret, c.want)
+		}
+
+		for i, r := range ret {
+			if r != c.want[i] {
+				t.Fatalf("ret: %q want %q\n", ret, c.want)
+			}
+		}
+	}
+}