Fix bugs in func huaPaiShortSplit, and created unit test for it

pkg/tiles/translate.go

@@ -31,7 +31,7 @@ func huaPaiShortSplit(num int) (string, error) {
 	if num < 1 || num > 8 {
 		return "", fmt.Errorf("invalid hua pai index %d", num)
 	}
-	return TileHuaTypes[num-1], fmt.Errorf("error calling huaPaiShortSplit()")
+	return TileHuaTypes[num-1], nil
 }
 
 func shortToArray(tiles string) ([]string, error) {

pkg/tiles/translate_test.go

@@ -7,6 +7,41 @@ import (
 	"testing"
 )
 
+func TestHuaPaiShortSplit(t *testing.T) {
+	testCases := []struct {
+		input  int
+		output string
+		err    error
+	}{
+		{0, "", fmt.Errorf("invalid hua pai index 0")},
+		{1, "ME", nil},
+		{2, "LA", nil},
+		{3, "ZU", nil},
+		{4, "JU", nil},
+		{5, "CH", nil},
+		{6, "XA", nil},
+		{7, "QI", nil},
+		{8, "DN", nil},
+		{9, "", fmt.Errorf("invalid hua pai index 9")},
+	}
+
+	for _, tc := range testCases {
+		t.Run(fmt.Sprintf("Test case %d", tc.input), func(t *testing.T) {
+			result, err := huaPaiShortSplit(tc.input)
+			if err != nil {
+				if tc.err != nil {
+					if err.Error() != tc.err.Error() {
+						t.Errorf("Expected error: %v, got: %v", tc.err, err)
+					}
+					return
+				}
+				t.Errorf("not expect error, but got %v", err)
+			} else if result != tc.output {
+				t.Errorf("Expected result: %v, got: %v", tc.output, result)
+			}
+		})
+	}
+}
 func TestShortToArray(t *testing.T) {
 	type testcase struct {
 		Name string