Merge aa02e412ac into a281c8b47b

command.go

@@ -863,7 +863,7 @@ func (c *Command) execute(a []string) (err error) {
 	}
 
 	if err := c.validateRequiredFlags(); err != nil {
-		return err
+		return c.FlagErrorFunc()(c, err)
 	}
 	if err := c.validateFlagGroups(); err != nil {
 		return err

command_test.go

@@ -17,6 +17,7 @@ package cobra
 import (
 	"bytes"
 	"context"
+	"errors"
 	"fmt"
 	"io/ioutil"
 	"os"
@@ -792,7 +793,6 @@ func TestRequiredFlags(t *testing.T) {
 	c.Flags().String("foo2", "", "")
 	assertNoErr(t, c.MarkFlagRequired("foo2"))
 	c.Flags().String("bar", "", "")
-
 	expected := fmt.Sprintf("required flag(s) %q, %q not set", "foo1", "foo2")
 
 	_, err := executeCommand(c)
@@ -803,6 +803,58 @@ func TestRequiredFlags(t *testing.T) {
 	}
 }
 
+func TestRequiredFlagsWithCustomFlagErrorFunc(t *testing.T) {
+	usageFunc := func(c *Command) error {
+		c.Println("usage string")
+		return nil
+	}
+	c := &Command{Use: "c", Run: emptyRun, SilenceUsage: true, usageFunc: usageFunc}
+	c.Flags().String("foo1", "", "")
+	assertNoErr(t, c.MarkFlagRequired("foo1"))
+	silentError := "failed flag parsing"
+	c.SetFlagErrorFunc(func(c *Command, err error) error {
+		c.Println(err)
+		c.Println(c.UsageString())
+		return errors.New(silentError)
+	})
+	requiredFlagErrorMessage := fmt.Sprintf("required flag(s) %q not set", "foo1")
+
+	output, err := executeCommand(c)
+
+	got := err.Error()
+	checkStringContains(t, output, requiredFlagErrorMessage)
+	checkStringContains(t, output, c.UsageString())
+	if got != silentError {
+		t.Errorf("Expected error %s but got %s", silentError, got)
+	}
+}
+
+func TestUnexistingFlagsWithCustomFlagErrorFunc(t *testing.T) {
+	usageFunc := func(c *Command) error {
+		c.Println("usage string")
+		return nil
+	}
+	c := &Command{Use: "c", Run: emptyRun, SilenceUsage: true, usageFunc: usageFunc}
+	c.Flags().String("foo1", "", "")
+	assertNoErr(t, c.MarkFlagRequired("foo1"))
+	silentError := "failed flag parsing"
+	c.SetFlagErrorFunc(func(c *Command, err error) error {
+		c.Println(err)
+		c.Println(c.UsageString())
+		return errors.New(silentError)
+	})
+	unknownFlagErrorMessage := fmt.Sprintf("unknown flag: %s", "--unknownflag")
+
+	output, err := executeCommand(c, "--unknownflag")
+
+	got := err.Error()
+	checkStringContains(t, output, unknownFlagErrorMessage)
+	checkStringContains(t, output, c.UsageString())
+	if got != silentError {
+		t.Errorf("Expected error %s but got %s", silentError, got)
+	}
+}
+
 func TestPersistentRequiredFlags(t *testing.T) {
 	parent := &Command{Use: "parent", Run: emptyRun}
 	parent.PersistentFlags().String("foo1", "", "")