GODRIVER-2616 Change CommandFailedEvent.Failure type to error (#1469)

Author: prestonvasquez

event/monitoring.go

@@ -55,7 +55,7 @@ type CommandSucceededEvent struct {
 // CommandFailedEvent represents an event generated when a command's execution fails.
 type CommandFailedEvent struct {
 	CommandFinishedEvent
-	Failure string
+	Failure error
 }
 
 // CommandMonitor represents a monitor that is triggered for different events.

mongo/client_test.go

@@ -341,7 +341,7 @@ func TestClient(t *testing.T) {
 			t.Run(tc.name, func(t *testing.T) {
 				// Setup a client and skip the test based on server version.
 				var started []*event.CommandStartedEvent
-				var failureReasons []string
+				var failureReasons []error
 				cmdMonitor := &event.CommandMonitor{
 					Started: func(_ context.Context, evt *event.CommandStartedEvent) {
 						if evt.CommandName == "endSessions" {

mongo/integration/unified/client_entity.go

@@ -408,7 +408,7 @@ func (c *clientEntity) processFailedEvent(_ context.Context, evt *event.CommandF
 		AppendString("commandName", evt.CommandName).
 		AppendInt64("requestId", evt.RequestID).
 		AppendString("connectionId", evt.ConnectionID).
-		AppendString("failure", evt.Failure)
+		AppendString("failure", evt.Failure.Error())
 	if evt.ServiceID != nil {
 		bsonBuilder.AppendString("serviceId", evt.ServiceID.String())
 	}

x/mongo/driver/operation.go

@@ -2032,7 +2032,7 @@ func (op Operation) publishFinishedEvent(ctx context.Context, info finishedInfor
 	}
 
 	failedEvent := &event.CommandFailedEvent{
-		Failure:              info.cmdErr.Error(),
+		Failure:              info.cmdErr,
 		CommandFinishedEvent: finished,
 	}
 	op.CommandMonitor.Failed(ctx, failedEvent)