Add backend to user friendly error message parsing

bindings/errors.go

+///////////////////////////////////////////////////////////////////////////////
+// Copyright © 2020 xx network SEZC                                          //
+//                                                                           //
+// Use of this source code is governed by a license that can be found in the //
+// LICENSE file                                                              //
+///////////////////////////////////////////////////////////////////////////////
+
+package bindings
+
+import (
+	"context"
+	"strings"
+)
+
+// ErrToUserErr maps backend patterns to user friendly error messages.
+// Example format:
+// (Back-end) "Building new HostPool because no HostList stored:":  (Front-end) "Missing host list",
+var ErrToUserErr = map[string]string{
+	// todo populate with common errors
+}
+
+// Error codes
+const UnrecognizedCode = "UR: "
+const UnrecognizedMessage = UnrecognizedCode + "Unrecognized error from XX backend, please report"
+
+// ErrorStringToUserFriendlyMessage takes a passed in errStr which will be
+// a backend generated error. These may be error specifically written by
+// the backend team or lower level errors gotten from low level dependencies.
+// This function will parse the error string for common errors provided from
+// ErrToUserErr to provide a more user-friendly error message for the front end.
+// If the error is not common, some simple parsing is done on the error message
+// to make it more user-accessible, removing backend specific jargon.
+func ErrorStringToUserFriendlyMessage(errStr string) string {
+	// Go through common errors
+	for backendErr, userFriendly := range ErrToUserErr {
+		// Determine if error contains a common error
+		// Fixme: later versions may be improved by using regex
+		if strings.HasPrefix(errStr, backendErr) {
+			return userFriendly
+		}
+	}
+
+	descStr := "desc = "
+	// If this contains an rpc error, determine how to handle it
+	if strings.Contains(errStr, context.DeadlineExceeded.Error()) {
+		// If there is a context deadline exceeded message, return the higher level
+		// as context deadline exceeded is not informative
+		rpcErr := "rpc "
+		rpcIdx := strings.Index(errStr, rpcErr)
+		return UnrecognizedCode + errStr[:rpcIdx]
+	} else if strings.Contains(errStr, descStr) {
+		// If containing an rpc error where context deadline exceeded
+		// is NOT involved, the error returned server-side is often
+		//more informative
+		descIdx := strings.Index(errStr, descStr)
+		// return everything after "desc = "
+		return UnrecognizedCode + errStr[descIdx+len(descStr):]
+	}
+
+	// If a compound error message, return the highest level message
+	errParts := strings.Split(errStr, ":")
+	if len(errParts) > 1 {
+		// Return everything before the first :
+		return UnrecognizedCode + errParts[0]
+	}
+
+	return UnrecognizedMessage
+}

bindings/errors_test.go

+///////////////////////////////////////////////////////////////////////////////
+// Copyright © 2020 xx network SEZC                                          //
+//                                                                           //
+// Use of this source code is governed by a license that can be found in the //
+// LICENSE file                                                              //
+///////////////////////////////////////////////////////////////////////////////
+
+package bindings
+
+import (
+	"context"
+	"strings"
+	"testing"
+)
+
+// Unit test
+func TestErrorStringToUserFriendlyMessage(t *testing.T) {
+	// Setup: Populate map
+	backendErrs := []string{"Failed to Unmarshal Conversation", "failed to create group key preimage",
+		"Failed to unmarshal SentRequestMap"}
+	userErrs := []string{"Could not retrieve conversation", "Failed to initiate group chat",
+		"Failed to pull up friend requests"}
+
+	for i, exampleErr := range backendErrs {
+		ErrToUserErr[exampleErr] = userErrs[i]
+	}
+
+	// Check if a mapped common error returns the expected user friendly error
+	received := ErrorStringToUserFriendlyMessage(backendErrs[0])
+	if strings.Compare(received, userErrs[0]) != 0 {
+		t.Errorf("Unexpected user friendly message returned from common error mapping."+
+			"\n\tExpected: %s"+
+			"\n\tReceived: %v", userErrs[0], received)
+	}
+
+	// Test RPC error in which high level information should
+	// be passed along (ie context deadline exceeded error)
+	expected := "Could not poll network: "
+	rpcPrefix := "rpc error: desc = "
+	rpcErr := expected + rpcPrefix + context.DeadlineExceeded.Error()
+	received = ErrorStringToUserFriendlyMessage(rpcErr)
+	if strings.Compare(UnrecognizedCode+expected, received) != 0 {
+		t.Errorf("Rpc error parsed unxecpectedly with error "+
+			"\n\"%s\" "+
+			"\n\tExpected: %s"+
+			"\n\tReceived: %v", rpcErr, UnrecognizedCode+expected, received)
+	}
+
+	// Test RPC error where server side error information is provided
+	serverSideError := "Could not parse message! Please try again with a properly crafted message"
+	rpcErr = rpcPrefix + serverSideError
+	received = ErrorStringToUserFriendlyMessage(rpcErr)
+	if strings.Compare(UnrecognizedCode+serverSideError, received) != 0 {
+		t.Errorf("RPC error parsed unexpectedly with error "+
+			"\n\"%s\" "+
+			"\n\tExpected: %s"+
+			"\n\tReceived: %v", rpcErr, UnrecognizedCode+serverSideError, received)
+	}
+
+	// Test uncommon error, should return highest level message
+	expected = "failed to register with permissioning"
+	uncommonErr := expected + ": sendRegistrationMessage: Unable to contact Identity Server"
+	received = ErrorStringToUserFriendlyMessage(uncommonErr)
+	if strings.Compare(received, UnrecognizedCode+expected) != 0 {
+		t.Errorf("Uncommon error parsed unexpectedly with error "+
+			"\n\"%s\" "+
+			"\n\tExpected: %s"+
+			"\n\tReceived: %s", uncommonErr, UnrecognizedCode+expected, received)
+	}
+
+	// Test fully unrecognizable and un-parsable message,
+	// should hardcoded error message
+	uncommonErr = "failed to register with permissioning"
+	received = ErrorStringToUserFriendlyMessage(uncommonErr)
+	if strings.Compare(UnrecognizedMessage, received) != 0 {
+		t.Errorf("Uncommon error parsed unexpectedly with error "+
+			"\n\"%s\" "+
+			"\n\tExpected: %s"+
+			"\n\tReceived: %s", uncommonErr, UnrecognizedMessage, received)
+	}
+
+}