feat: added custom error handler function

command.go

@@ -161,6 +161,9 @@ type Command struct {
 	// versionTemplate is the version template defined by user.
 	versionTemplate string
 
+	// errorHandlerFunc allows setting a custom error handler by the user.
+	errorHandlerFunc func(error)
+
 	// inReader is a reader defined by the user that replaces stdin
 	inReader io.Reader
 	// outWriter is a writer defined by the user that replaces stdout
@@ -323,6 +326,12 @@ func (c *Command) SetGlobalNormalizationFunc(n func(f *flag.FlagSet, name string
 	}
 }
 
+// SetErrorHandlerFunc is the function that will be called, if set, when there is any kind of error in the
+// execution of the command.
+func (c *Command) SetErrorHandlerFunc(f func(error)) {
+	c.errorHandlerFunc = f
+}
+
 // OutOrStdout returns output to stdout.
 func (c *Command) OutOrStdout() io.Writer {
 	return c.getOut(os.Stdout)
@@ -979,7 +988,11 @@ func (c *Command) ExecuteC() (cmd *Command, err error) {
 			c = cmd
 		}
 		if !c.SilenceErrors {
+			if c.errorHandlerFunc != nil {
+				c.errorHandlerFunc(err)
+			} else {
 				c.PrintErrln("Error:", err.Error())
+			}
 			c.PrintErrf("Run '%v --help' for usage.\n", c.CommandPath())
 		}
 		return c, err
@@ -1008,8 +1021,12 @@ func (c *Command) ExecuteC() (cmd *Command, err error) {
 		// If root command has SilenceErrors flagged,
 		// all subcommands should respect it
 		if !cmd.SilenceErrors && !c.SilenceErrors {
+			if c.errorHandlerFunc != nil {
+				c.errorHandlerFunc(err)
+			} else {
 				c.PrintErrln("Error:", err.Error())
 			}
+		}
 
 		// If root command has SilenceUsage flagged,
 		// all subcommands should respect it

command_test.go

@@ -17,6 +17,7 @@ package cobra
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -2430,3 +2431,23 @@ func TestHelpflagCommandExecutedWithoutVersionSet(t *testing.T) {
 	checkStringContains(t, output, HelpFlag)
 	checkStringOmits(t, output, VersionFlag)
 }
+
+func TestSetCustomErrorHandler(t *testing.T) {
+	var writer bytes.Buffer
+	handler := func(err error) {
+		writer.Write([]byte(err.Error()))
+	}
+
+	root := &Command{
+		Use: "root",
+		RunE: func(cmd *Command, args []string) error {
+			return errors.New("test error handler function")
+		},
+		SilenceUsage: true,
+	}
+	root.SetErrorHandlerFunc(handler)
+	_ = root.Execute()
+	if writer.String() != "test error handler function" {
+		t.Errorf("Expected error handler to contain [%s] instead it contains [%s]", "test error handler function", writer.String())
+	}
+}