Add unwrap error message to callback and utilise in responder

Signed-off-by: Joshua Medley <[email protected]>

errors/callback.go

@@ -94,17 +94,36 @@ func StackTrace(err error) []log.EventStackTrace {
 }
 
 // ErrorMessage extracts a specified error response to be returned
-// to the caller if present, otherwise returns the default error
-// string
+// to the caller if present, otherwise returns an empty string
 func ErrorMessage(err error) string {
 	var rerr messager
 	if errors.As(err, &rerr) {
-		if resp := rerr.Message(); resp != "" {
-			return resp
+		return rerr.Message()
+	}
+
+	return ""
+}
+
+// UnwrapErrorMessage is a callback function that allows you to extract
+// an error message from an error. If the error message returned is an empty
+// string, UnwrapErrorMessage will attempt to recursively unwrap the error
+// until a non-empty string is returned. If no message is returned it will
+// return the original error's error string as default.
+func UnwrapErrorMessage(err error) string {
+	originalErr := err
+
+	if msg := ErrorMessage(err); msg != "" {
+		return msg
+	}
+
+	for errors.Unwrap(err) != nil {
+		if msg := ErrorMessage(err); msg != "" {
+			return msg
 		}
+		err = errors.Unwrap(err)
 	}
 
-	return err.Error()
+	return originalErr.Error()
 }
 
 // UnwrapStatusCode is a callback function that allows you to extract

errors/callback_test.go

@@ -15,6 +15,7 @@ import (
 type testError struct {
 	err        error
 	statusCode int
+	message    string
 	logData    map[string]interface{}
 }
 
@@ -37,6 +38,10 @@ func (e testError) LogData() map[string]interface{} {
 	return e.logData
 }
 
+func (e testError) Message() string {
+	return e.message
+}
+
 func TestUnwrapLogDataHappy(t *testing.T) {
 
 	Convey("Given an error with embedded logData", t, func() {
@@ -237,3 +242,81 @@ func TestUnwrapStatusCodeHappy(t *testing.T) {
 	})
 
 }
+
+func TestUnwrapErrorMessageHappy(t *testing.T) {
+
+	Convey("Given an error with embedded error message", t, func() {
+		err := &testError{
+			message: "I am an error message",
+		}
+
+		Convey("When ErrorMessage(err) is called", func() {
+			status := dperrors.ErrorMessage(err)
+			expected := "I am an error message"
+
+			So(status, ShouldEqual, expected)
+		})
+	})
+
+	Convey("Given an error chain with embedded error message", t, func() {
+		err1 := &testError{
+			err:     errors.New("original error"),
+			message: "I am embedded message",
+		}
+
+		err2 := &testError{
+			err: fmt.Errorf("err1: %w", err1),
+		}
+
+		err3 := &testError{
+			err: fmt.Errorf("err2: %w", err2),
+		}
+
+		Convey("When UnwrapErrorMessage(err) is called", func() {
+			status := dperrors.UnwrapErrorMessage(err3)
+			expected := "I am embedded message"
+
+			So(status, ShouldEqual, expected)
+		})
+	})
+
+	Convey("Given an error chain with multiple embedded status codes", t, func() {
+		err1 := &testError{
+			err:     errors.New("original error"),
+			message: "I am embedded message",
+		}
+
+		err2 := &testError{
+			err:     fmt.Errorf("err1: %w", err1),
+			message: "I am first embedded message",
+		}
+
+		err3 := &testError{
+			err: fmt.Errorf("err2: %w", err2),
+		}
+
+		Convey("When UnwrapErrorMessage(err) is called", func() {
+			status := dperrors.UnwrapErrorMessage(err3)
+			expected := "I am first embedded message"
+
+			Convey("The first valid error message is returned ", func() {
+				So(status, ShouldEqual, expected)
+			})
+		})
+	})
+
+	Convey("Given an error with no embedded error message", t, func() {
+		err := &testError{
+			err: errors.New("original error"),
+		}
+
+		Convey("When StatusCode(err) is called", func() {
+			status := dperrors.UnwrapErrorMessage(err)
+			expected := "original error"
+
+			Convey("The orinal error string is returned ", func() {
+				So(status, ShouldEqual, expected)
+			})
+		})
+	})
+}

responder/responder.go

@@ -65,7 +65,7 @@ func respondError(ctx context.Context, w http.ResponseWriter, status int, err er
 		status = http.StatusInternalServerError
 	}
 
-	msg := dperrors.ErrorMessage(err)
+	msg := dperrors.UnwrapErrorMessage(err)
 	resp := errorResponse{
 		Errors: []string{msg},
 	}
@@ -108,7 +108,7 @@ func (r *Responder) Errors(ctx context.Context, w http.ResponseWriter, status in
 			StackTrace: dperrors.StackTrace(err),
 			Data:       dperrors.UnwrapLogData(err),
 		})
-		errorMsgs = append(errorMsgs, dperrors.ErrorMessage(err))
+		errorMsgs = append(errorMsgs, dperrors.UnwrapErrorMessage(err))
 	}
 
 	log.Info(ctx, "error responding to HTTP request", log.ERROR, &errorLogs)