Make json file storing single responsible (#81)

* Make json file storing single responsible

* Fix test

file/json.go

@@ -14,18 +14,22 @@ const (
 	prefix            = ""
 )
 
-func CreateJSONFile(path string, payload interface{}) error {
+func PrepareJSONData(payload interface{}) ([]byte, error) {
 	data, err := json.MarshalIndent(payload, prefix, indent)
 	if err != nil {
-		return fmt.Errorf("failed to marshal json: %w", err)
+		return nil, fmt.Errorf("failed to marshal json: %w", err)
 	}
 
 	// The solution of escaping special HTML characters in golang json.marshal.
 	data = bytes.ReplaceAll(data, []byte("\\u003c"), []byte("<"))
 	data = bytes.ReplaceAll(data, []byte("\\u003e"), []byte(">"))
 	data = bytes.ReplaceAll(data, []byte("\\u0026"), []byte("&"))
 
-	err = ioutil.WriteFile(path, data, fileModeReadWrite)
+	return data, nil
+}
+
+func CreateJSONFile(path string, data []byte) error {
+	err := ioutil.WriteFile(path, data, fileModeReadWrite)
 	if err != nil {
 		return fmt.Errorf("failed to write json to file: %w", err)
 	}

file/json_test.go

@@ -0,0 +1,50 @@
+package file
+
+import (
+	"reflect"
+	"testing"
+)
+
+func TestPrepareJSONData(t *testing.T) {
+	type args struct {
+		payload interface{}
+	}
+	tests := []struct {
+		name    string
+		args    args
+		want    []byte
+		wantErr bool
+	}{
+		{
+			name: "ok",
+			args: args{
+				payload: struct {
+					Name string `json:"name"`
+				}{Name: "\u003ctest"},
+			},
+			wantErr: false,
+			want:    []byte("{\n    \"name\": \"<test\"\n}"),
+		},
+		{
+			name: "wrong_json",
+			args: args{
+				payload: struct {
+					C chan int
+				}{},
+			},
+			wantErr: true,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got, err := PrepareJSONData(tt.args.payload)
+			if (err != nil) != tt.wantErr {
+				t.Errorf("PrepareJSONData() error = %v, wantErr %v", err, tt.wantErr)
+				return
+			}
+			if !reflect.DeepEqual(got, tt.want) {
+				t.Errorf("PrepareJSONData() got = %v, want %v", got, tt.want)
+			}
+		})
+	}
+}