key: Add slice key stringification

Change-Id: I0dd855c771a91f7f12dbba06560d8e973ded4881

key/stringify.go

@@ -69,7 +69,12 @@ func StringifyInterface(key interface{}) (string, error) {
 			keys[i] = stringify(k) + "=" + stringify(m[k])
 		}
 		str = strings.Join(keys, "_")
-
+	case []interface{}:
+		elements := make([]string, len(key))
+		for i, element := range key {
+			elements[i] = stringify(element)
+		}
+		str = strings.Join(elements, ",")
 	case value.Value:
 		return key.String(), nil
 

key/stringify_test.go

@@ -119,6 +119,18 @@ func TestStringify(t *testing.T) {
 			"n": nil,
 		},
 		output: "Unable to stringify nil",
+	}, {
+		name: "[]interface{}",
+		input: []interface{}{
+			uint32(42),
+			true,
+			"foo",
+			map[Key]interface{}{
+				New("a"): "b",
+				New("b"): "c",
+			},
+		},
+		output: "42,true,foo,a=b_b=c",
 	}}
 
 	for _, tcase := range testcases {