feature (errors): add support fmt specifier with operands to WithMsg(...) (#2126)

internal/errors/error.go

@@ -74,7 +74,7 @@ func E(ctx context.Context, opt ...Option) error {
 		Code:    code,
 		Op:      opts.withOp,
 		Wrapped: opts.withErrWrapped,
-		Msg:     opts.withErrMsg,
+		Msg:     fmt.Sprintf(opts.withErrMsg, opts.withErrMsgArgs...),
 	}
 	if opts.withoutEvent {
 		return err

internal/errors/option.go

@@ -17,6 +17,7 @@ type Options struct {
 	withCode       Code
 	withErrWrapped error
 	withErrMsg     string
+	withErrMsgArgs []any
 	withOp         Op
 	withoutEvent   bool
 }
@@ -34,10 +35,12 @@ func WithWrap(e error) Option {
 }
 
 // WithMsg provides an option to provide a message when creating a new
-// error.
-func WithMsg(msg string) Option {
+// error.  If args are provided, the the msg string is used as a fmt specifier
+// for the arguments and the resulting string is used as the msg.
+func WithMsg(msg string, args ...any) Option {
 	return func(o *Options) {
 		o.withErrMsg = msg
+		o.withErrMsgArgs = args
 	}
 }
 

internal/errors/option_test.go

@@ -22,6 +22,13 @@ func Test_getOpts(t *testing.T) {
 		opts = GetOpts(WithMsg("test msg"))
 		testOpts.withErrMsg = "test msg"
 		assert.Equal(opts, testOpts)
+
+		opts = GetOpts(WithMsg("%s msg", "test"))
+		testOpts.withErrMsg = "%s msg"
+		testOpts.withErrMsgArgs = []any{"test"}
+		assert.Equal(opts, testOpts)
+
+		assert.Equal("#1 test msg: unknown: error #0", E(context.Background(), WithMsg("#%d %s msg", 1, "test")).Error())
 	})
 	t.Run("WithWrap", func(t *testing.T) {
 		assert := assert.New(t)