From 41205a05f578993e1278f6b706a7046179e8c984 Mon Sep 17 00:00:00 2001
From: umarcor <unai.martinezcorral@ehu.eus>
Date: Fri, 7 Jun 2019 18:33:29 +0200
Subject: [PATCH] use golangci-lint (#876) (#1044)

---
 .gitattributes                    |   1 +
 .golangci.yml                     |  25 ++++
 .travis.yml                       |   7 +-
 Makefile                          |  18 +--
 README.md                         |   4 +-
 bash_completions.go               | 127 +++++++++----------
 bash_completions_test.go          |  37 +++---
 cobra.go                          |  16 +++
 cobra/cmd/add.go                  |   4 +-
 cobra/cmd/add_test.go             |   6 +-
 cobra/cmd/golden_test.go          |  27 ----
 cobra/cmd/helpers.go              | 110 +----------------
 cobra/cmd/init.go                 |   2 +-
 cobra/cmd/init_test.go            |   4 +-
 cobra/cmd/licenses.go             |   3 +-
 cobra/cmd/project.go              |   2 +-
 cobra/cmd/root.go                 |   8 +-
 cobra/cmd/testdata/root.go.golden |   7 +-
 cobra/tpl/main.go                 |  10 +-
 command.go                        | 112 ++++++++---------
 command_test.go                   | 197 ++++++++++++++----------------
 doc/man_docs.go                   |  28 ++---
 doc/man_docs_test.go              |   2 +-
 doc/man_examples_test.go          |   8 +-
 doc/util.go                       |   9 ++
 go.mod                            |   1 -
 go.sum                            |   2 -
 powershell_completions_test.go    |   2 +-
 zsh_completions_test.go           |  28 ++---
 29 files changed, 357 insertions(+), 450 deletions(-)
 create mode 100644 .gitattributes
 create mode 100644 .golangci.yml

diff --git a/.gitattributes b/.gitattributes
new file mode 100644
index 000000000..212566614
--- /dev/null
+++ b/.gitattributes
@@ -0,0 +1 @@
+* text=auto
\ No newline at end of file
diff --git a/.golangci.yml b/.golangci.yml
new file mode 100644
index 000000000..8450df644
--- /dev/null
+++ b/.golangci.yml
@@ -0,0 +1,25 @@
+run:
+  deadline: 5m
+
+linters:
+  enable:
+    - deadcode
+    - errcheck
+    - gas
+    - goconst
+    - goimports
+    - golint
+    - govet
+    - ineffassign
+    - interfacer
+    - maligned
+    - megacheck
+    - structcheck
+    - unconvert
+    - varcheck
+  enable-all: false
+  disable-all: true
+#  presets:
+#    - bugs
+#    - unused
+  fast: false
diff --git a/.travis.yml b/.travis.yml
index 9543eee99..35b3500ce 100644
--- a/.travis.yml
+++ b/.travis.yml
@@ -1,7 +1,6 @@
 language: go
 
 stages:
-  - diff
   - test
   - build
 
@@ -10,9 +9,12 @@ go:
   - 1.13.x
   - tip
 
+env: GO111MODULE=on
+
 before_install:
   - go get -u github.com/kyoh86/richgo
   - go get -u github.com/mitchellh/gox
+  - curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh -s -- -b $(go env GOPATH)/bin latest
 
 env:
   - GO111MODULE=on
@@ -21,9 +23,6 @@ matrix:
   allow_failures:
     - go: tip
   include:
-    - stage: diff
-      go: 1.13.x
-      script: make fmt
     - stage: build
       go: 1.13.x
       script: make cobra_generator
diff --git a/Makefile b/Makefile
index e9740d1e1..dd2ccd601 100644
--- a/Makefile
+++ b/Makefile
@@ -1,21 +1,29 @@
 BIN="./bin"
 SRC=$(shell find . -name "*.go")
 
+ifeq (, $(shell which golangci-lint))
+$(warning "could not find golangci-lint in $(PATH), run: curl -sfL https://install.goreleaser.com/github.com/golangci/golangci-lint.sh | sh")
+endif
+
 ifeq (, $(shell which richgo))
 $(warning "could not find richgo in $(PATH), run: go get github.com/kyoh86/richgo")
 endif
 
-.PHONY: fmt vet test cobra_generator install_deps clean
+.PHONY: fmt lint test cobra_generator install_deps clean
 
 default: all
 
-all: fmt vet test cobra_generator	
+all: fmt lint test cobra_generator
 
 fmt:
 	$(info ******************** checking formatting ********************)
 	@test -z $(shell gofmt -l $(SRC)) || (gofmt -d $(SRC); exit 1)
 
-test: install_deps vet
+lint:
+	$(info ******************** running lint tools ********************)
+	golangci-lint run -v
+
+test: install_deps lint
 	$(info ******************** running tests ********************)
 	richgo test -v ./...
 
@@ -28,9 +36,5 @@ install_deps:
 	$(info ******************** downloading dependencies ********************)
 	go get -v ./...
 
-vet:
-	$(info ******************** vetting ********************)
-	go vet ./...
-
 clean:
 	rm -rf $(BIN)
diff --git a/README.md b/README.md
index 52fa148f4..7c6281f86 100644
--- a/README.md
+++ b/README.md
@@ -216,7 +216,6 @@ import (
 	"fmt"
 	"os"
 
-	homedir "github.com/mitchellh/go-homedir"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 )
@@ -267,7 +266,7 @@ func initConfig() {
 		viper.SetConfigFile(cfgFile)
 	} else {
 		// Find home directory.
-		home, err := homedir.Dir()
+		home, err := os.UserHomeDir()
 		if err != nil {
 			er(err)
 		}
@@ -276,7 +275,6 @@ func initConfig() {
 		viper.AddConfigPath(home)
 		viper.SetConfigName(".cobra")
 	}
-
 	viper.AutomaticEnv()
 
 	if err := viper.ReadInConfig(); err == nil {
diff --git a/bash_completions.go b/bash_completions.go
index 1e0e25cf6..5ca20155d 100644
--- a/bash_completions.go
+++ b/bash_completions.go
@@ -19,9 +19,9 @@ const (
 	BashCompSubdirsInDir    = "cobra_annotation_bash_completion_subdirs_in_dir"
 )
 
-func writePreamble(buf *bytes.Buffer, name string) {
-	buf.WriteString(fmt.Sprintf("# bash completion for %-36s -*- shell-script -*-\n", name))
-	buf.WriteString(fmt.Sprintf(`
+func writePreamble(buf io.StringWriter, name string) {
+	WrStringAndCheck(buf, fmt.Sprintf("# bash completion for %-36s -*- shell-script -*-\n", name))
+	WrStringAndCheck(buf, fmt.Sprintf(`
 __%[1]s_debug()
 {
     if [[ -n ${BASH_COMP_DEBUG_FILE} ]]; then
@@ -282,10 +282,10 @@ __%[1]s_handle_word()
 `, name))
 }
 
-func writePostscript(buf *bytes.Buffer, name string) {
+func writePostscript(buf io.StringWriter, name string) {
 	name = strings.Replace(name, ":", "__", -1)
-	buf.WriteString(fmt.Sprintf("__start_%s()\n", name))
-	buf.WriteString(fmt.Sprintf(`{
+	WrStringAndCheck(buf, fmt.Sprintf("__start_%s()\n", name))
+	WrStringAndCheck(buf, fmt.Sprintf(`{
     local cur prev words cword
     declare -A flaghash 2>/dev/null || :
     declare -A aliashash 2>/dev/null || :
@@ -311,33 +311,33 @@ func writePostscript(buf *bytes.Buffer, name string) {
 }
 
 `, name))
-	buf.WriteString(fmt.Sprintf(`if [[ $(type -t compopt) = "builtin" ]]; then
+	WrStringAndCheck(buf, fmt.Sprintf(`if [[ $(type -t compopt) = "builtin" ]]; then
     complete -o default -F __start_%s %s
 else
     complete -o default -o nospace -F __start_%s %s
 fi
 
 `, name, name, name, name))
-	buf.WriteString("# ex: ts=4 sw=4 et filetype=sh\n")
+	WrStringAndCheck(buf, "# ex: ts=4 sw=4 et filetype=sh\n")
 }
 
-func writeCommands(buf *bytes.Buffer, cmd *Command) {
-	buf.WriteString("    commands=()\n")
+func writeCommands(buf io.StringWriter, cmd *Command) {
+	WrStringAndCheck(buf, "    commands=()\n")
 	for _, c := range cmd.Commands() {
 		if !c.IsAvailableCommand() || c == cmd.helpCommand {
 			continue
 		}
-		buf.WriteString(fmt.Sprintf("    commands+=(%q)\n", c.Name()))
+		WrStringAndCheck(buf, fmt.Sprintf("    commands+=(%q)\n", c.Name()))
 		writeCmdAliases(buf, c)
 	}
-	buf.WriteString("\n")
+	WrStringAndCheck(buf, "\n")
 }
 
-func writeFlagHandler(buf *bytes.Buffer, name string, annotations map[string][]string, cmd *Command) {
+func writeFlagHandler(buf io.StringWriter, name string, annotations map[string][]string, cmd *Command) {
 	for key, value := range annotations {
 		switch key {
 		case BashCompFilenameExt:
-			buf.WriteString(fmt.Sprintf("    flags_with_completion+=(%q)\n", name))
+			WrStringAndCheck(buf, fmt.Sprintf("    flags_with_completion+=(%q)\n", name))
 
 			var ext string
 			if len(value) > 0 {
@@ -345,17 +345,18 @@ func writeFlagHandler(buf *bytes.Buffer, name string, annotations map[string][]s
 			} else {
 				ext = "_filedir"
 			}
-			buf.WriteString(fmt.Sprintf("    flags_completion+=(%q)\n", ext))
+			WrStringAndCheck(buf, fmt.Sprintf("    flags_completion+=(%q)\n", ext))
 		case BashCompCustom:
-			buf.WriteString(fmt.Sprintf("    flags_with_completion+=(%q)\n", name))
+			WrStringAndCheck(buf, fmt.Sprintf("    flags_with_completion+=(%q)\n", name))
+
 			if len(value) > 0 {
 				handlers := strings.Join(value, "; ")
-				buf.WriteString(fmt.Sprintf("    flags_completion+=(%q)\n", handlers))
+				WrStringAndCheck(buf, fmt.Sprintf("    flags_completion+=(%q)\n", handlers))
 			} else {
-				buf.WriteString("    flags_completion+=(:)\n")
+				WrStringAndCheck(buf, "    flags_completion+=(:)\n")
 			}
 		case BashCompSubdirsInDir:
-			buf.WriteString(fmt.Sprintf("    flags_with_completion+=(%q)\n", name))
+			WrStringAndCheck(buf, fmt.Sprintf("    flags_with_completion+=(%q)\n", name))
 
 			var ext string
 			if len(value) == 1 {
@@ -363,49 +364,51 @@ func writeFlagHandler(buf *bytes.Buffer, name string, annotations map[string][]s
 			} else {
 				ext = "_filedir -d"
 			}
-			buf.WriteString(fmt.Sprintf("    flags_completion+=(%q)\n", ext))
+			WrStringAndCheck(buf, fmt.Sprintf("    flags_completion+=(%q)\n", ext))
 		}
 	}
 }
 
-func writeShortFlag(buf *bytes.Buffer, flag *pflag.Flag, cmd *Command) {
+const cbn = "\")\n"
+
+func writeShortFlag(buf io.StringWriter, flag *pflag.Flag, cmd *Command) {
 	name := flag.Shorthand
 	format := "    "
 	if len(flag.NoOptDefVal) == 0 {
 		format += "two_word_"
 	}
-	format += "flags+=(\"-%s\")\n"
-	buf.WriteString(fmt.Sprintf(format, name))
+	format += "flags+=(\"-%s" + cbn
+	WrStringAndCheck(buf, fmt.Sprintf(format, name))
 	writeFlagHandler(buf, "-"+name, flag.Annotations, cmd)
 }
 
-func writeFlag(buf *bytes.Buffer, flag *pflag.Flag, cmd *Command) {
+func writeFlag(buf io.StringWriter, flag *pflag.Flag, cmd *Command) {
 	name := flag.Name
 	format := "    flags+=(\"--%s"
 	if len(flag.NoOptDefVal) == 0 {
 		format += "="
 	}
-	format += "\")\n"
-	buf.WriteString(fmt.Sprintf(format, name))
+	format += cbn
+	WrStringAndCheck(buf, fmt.Sprintf(format, name))
 	if len(flag.NoOptDefVal) == 0 {
-		format = "    two_word_flags+=(\"--%s\")\n"
-		buf.WriteString(fmt.Sprintf(format, name))
+		format = "    two_word_flags+=(\"--%s" + cbn
+		WrStringAndCheck(buf, fmt.Sprintf(format, name))
 	}
 	writeFlagHandler(buf, "--"+name, flag.Annotations, cmd)
 }
 
-func writeLocalNonPersistentFlag(buf *bytes.Buffer, flag *pflag.Flag) {
+func writeLocalNonPersistentFlag(buf io.StringWriter, flag *pflag.Flag) {
 	name := flag.Name
 	format := "    local_nonpersistent_flags+=(\"--%s"
 	if len(flag.NoOptDefVal) == 0 {
 		format += "="
 	}
-	format += "\")\n"
-	buf.WriteString(fmt.Sprintf(format, name))
+	format += cbn
+	WrStringAndCheck(buf, fmt.Sprintf(format, name))
 }
 
-func writeFlags(buf *bytes.Buffer, cmd *Command) {
-	buf.WriteString(`    flags=()
+func writeFlags(buf io.StringWriter, cmd *Command) {
+	WrStringAndCheck(buf, `    flags=()
     two_word_flags=()
     local_nonpersistent_flags=()
     flags_with_completion=()
@@ -435,11 +438,11 @@ func writeFlags(buf *bytes.Buffer, cmd *Command) {
 		}
 	})
 
-	buf.WriteString("\n")
+	WrStringAndCheck(buf, "\n")
 }
 
-func writeRequiredFlag(buf *bytes.Buffer, cmd *Command) {
-	buf.WriteString("    must_have_one_flag=()\n")
+func writeRequiredFlag(buf io.StringWriter, cmd *Command) {
+	WrStringAndCheck(buf, "    must_have_one_flag=()\n")
 	flags := cmd.NonInheritedFlags()
 	flags.VisitAll(func(flag *pflag.Flag) {
 		if nonCompletableFlag(flag) {
@@ -452,49 +455,49 @@ func writeRequiredFlag(buf *bytes.Buffer, cmd *Command) {
 				if flag.Value.Type() != "bool" {
 					format += "="
 				}
-				format += "\")\n"
-				buf.WriteString(fmt.Sprintf(format, flag.Name))
+				format += cbn
+				WrStringAndCheck(buf, fmt.Sprintf(format, flag.Name))
 
 				if len(flag.Shorthand) > 0 {
-					buf.WriteString(fmt.Sprintf("    must_have_one_flag+=(\"-%s\")\n", flag.Shorthand))
+					WrStringAndCheck(buf, fmt.Sprintf("    must_have_one_flag+=(\"-%s"+cbn, flag.Shorthand))
 				}
 			}
 		}
 	})
 }
 
-func writeRequiredNouns(buf *bytes.Buffer, cmd *Command) {
-	buf.WriteString("    must_have_one_noun=()\n")
-	sort.Sort(sort.StringSlice(cmd.ValidArgs))
+func writeRequiredNouns(buf io.StringWriter, cmd *Command) {
+	WrStringAndCheck(buf, "    must_have_one_noun=()\n")
+	sort.Strings(cmd.ValidArgs)
 	for _, value := range cmd.ValidArgs {
-		buf.WriteString(fmt.Sprintf("    must_have_one_noun+=(%q)\n", value))
+		WrStringAndCheck(buf, fmt.Sprintf("    must_have_one_noun+=(%q)\n", value))
 	}
 }
 
-func writeCmdAliases(buf *bytes.Buffer, cmd *Command) {
+func writeCmdAliases(buf io.StringWriter, cmd *Command) {
 	if len(cmd.Aliases) == 0 {
 		return
 	}
 
-	sort.Sort(sort.StringSlice(cmd.Aliases))
+	sort.Strings(cmd.Aliases)
 
-	buf.WriteString(fmt.Sprint(`    if [[ -z "${BASH_VERSION}" || "${BASH_VERSINFO[0]}" -gt 3 ]]; then`, "\n"))
+	WrStringAndCheck(buf, fmt.Sprint(`    if [[ -z "${BASH_VERSION}" || "${BASH_VERSINFO[0]}" -gt 3 ]]; then`, "\n"))
 	for _, value := range cmd.Aliases {
-		buf.WriteString(fmt.Sprintf("        command_aliases+=(%q)\n", value))
-		buf.WriteString(fmt.Sprintf("        aliashash[%q]=%q\n", value, cmd.Name()))
+		WrStringAndCheck(buf, fmt.Sprintf("        command_aliases+=(%q)\n", value))
+		WrStringAndCheck(buf, fmt.Sprintf("        aliashash[%q]=%q\n", value, cmd.Name()))
 	}
-	buf.WriteString(`    fi`)
-	buf.WriteString("\n")
+	WrStringAndCheck(buf, `    fi`)
+	WrStringAndCheck(buf, "\n")
 }
-func writeArgAliases(buf *bytes.Buffer, cmd *Command) {
-	buf.WriteString("    noun_aliases=()\n")
-	sort.Sort(sort.StringSlice(cmd.ArgAliases))
+func writeArgAliases(buf io.StringWriter, cmd *Command) {
+	WrStringAndCheck(buf, "    noun_aliases=()\n")
+	sort.Strings(cmd.ArgAliases)
 	for _, value := range cmd.ArgAliases {
-		buf.WriteString(fmt.Sprintf("    noun_aliases+=(%q)\n", value))
+		WrStringAndCheck(buf, fmt.Sprintf("    noun_aliases+=(%q)\n", value))
 	}
 }
 
-func gen(buf *bytes.Buffer, cmd *Command) {
+func gen(buf io.StringWriter, cmd *Command) {
 	for _, c := range cmd.Commands() {
 		if !c.IsAvailableCommand() || c == cmd.helpCommand {
 			continue
@@ -506,22 +509,22 @@ func gen(buf *bytes.Buffer, cmd *Command) {
 	commandName = strings.Replace(commandName, ":", "__", -1)
 
 	if cmd.Root() == cmd {
-		buf.WriteString(fmt.Sprintf("_%s_root_command()\n{\n", commandName))
+		WrStringAndCheck(buf, fmt.Sprintf("_%s_root_command()\n{\n", commandName))
 	} else {
-		buf.WriteString(fmt.Sprintf("_%s()\n{\n", commandName))
+		WrStringAndCheck(buf, fmt.Sprintf("_%s()\n{\n", commandName))
 	}
 
-	buf.WriteString(fmt.Sprintf("    last_command=%q\n", commandName))
-	buf.WriteString("\n")
-	buf.WriteString("    command_aliases=()\n")
-	buf.WriteString("\n")
+	WrStringAndCheck(buf, fmt.Sprintf("    last_command=%q\n", commandName))
+	WrStringAndCheck(buf, "\n")
+	WrStringAndCheck(buf, "    command_aliases=()\n")
+	WrStringAndCheck(buf, "\n")
 
 	writeCommands(buf, cmd)
 	writeFlags(buf, cmd)
 	writeRequiredFlag(buf, cmd)
 	writeRequiredNouns(buf, cmd)
 	writeArgAliases(buf, cmd)
-	buf.WriteString("}\n\n")
+	WrStringAndCheck(buf, "}\n\n")
 }
 
 // GenBashCompletion generates bash completion file and writes to the passed writer.
diff --git a/bash_completions_test.go b/bash_completions_test.go
index 55b56f8af..b9e031778 100644
--- a/bash_completions_test.go
+++ b/bash_completions_test.go
@@ -40,10 +40,9 @@ func checkRegex(t *testing.T, found, pattern string) {
 }
 
 func runShellCheck(s string) error {
-	excluded := []string{
+	cmd := exec.Command("shellcheck", "-s", "bash", "-", "-e",
 		"SC2034", // PREFIX appears unused. Verify it or export it.
-	}
-	cmd := exec.Command("shellcheck", "-s", "bash", "-", "-e", strings.Join(excluded, ","))
+	)
 	cmd.Stderr = os.Stderr
 	cmd.Stdout = os.Stdout
 
@@ -52,7 +51,9 @@ func runShellCheck(s string) error {
 		return err
 	}
 	go func() {
-		stdin.Write([]byte(s))
+		_, err := stdin.Write([]byte(s))
+		er(err)
+
 		stdin.Close()
 	}()
 
@@ -74,26 +75,26 @@ func TestBashCompletions(t *testing.T) {
 		Run:                    emptyRun,
 	}
 	rootCmd.Flags().IntP("introot", "i", -1, "help message for flag introot")
-	rootCmd.MarkFlagRequired("introot")
+	er(rootCmd.MarkFlagRequired("introot"))
 
 	// Filename.
 	rootCmd.Flags().String("filename", "", "Enter a filename")
-	rootCmd.MarkFlagFilename("filename", "json", "yaml", "yml")
+	er(rootCmd.MarkFlagFilename("filename", "json", "yaml", "yml"))
 
 	// Persistent filename.
 	rootCmd.PersistentFlags().String("persistent-filename", "", "Enter a filename")
-	rootCmd.MarkPersistentFlagFilename("persistent-filename")
-	rootCmd.MarkPersistentFlagRequired("persistent-filename")
+	er(rootCmd.MarkPersistentFlagFilename("persistent-filename"))
+	er(rootCmd.MarkPersistentFlagRequired("persistent-filename"))
 
 	// Filename extensions.
 	rootCmd.Flags().String("filename-ext", "", "Enter a filename (extension limited)")
-	rootCmd.MarkFlagFilename("filename-ext")
+	er(rootCmd.MarkFlagFilename("filename-ext"))
 	rootCmd.Flags().String("custom", "", "Enter a filename (extension limited)")
-	rootCmd.MarkFlagCustom("custom", "__complete_custom")
+	er(rootCmd.MarkFlagCustom("custom", "__complete_custom"))
 
 	// Subdirectories in a given directory.
 	rootCmd.Flags().String("theme", "", "theme to use (located in /themes/THEMENAME/)")
-	rootCmd.Flags().SetAnnotation("theme", BashCompSubdirsInDir, []string{"themes"})
+	er(rootCmd.Flags().SetAnnotation("theme", BashCompSubdirsInDir, []string{"themes"}))
 
 	// For two word flags check
 	rootCmd.Flags().StringP("two", "t", "", "this is two word flags")
@@ -109,9 +110,9 @@ func TestBashCompletions(t *testing.T) {
 	}
 
 	echoCmd.Flags().String("filename", "", "Enter a filename")
-	echoCmd.MarkFlagFilename("filename", "json", "yaml", "yml")
+	er(echoCmd.MarkFlagFilename("filename", "json", "yaml", "yml"))
 	echoCmd.Flags().String("config", "", "config to use (located in /config/PROFILE/)")
-	echoCmd.Flags().SetAnnotation("config", BashCompSubdirsInDir, []string{"config"})
+	er(echoCmd.Flags().SetAnnotation("config", BashCompSubdirsInDir, []string{"config"}))
 
 	printCmd := &Command{
 		Use:   "print [string to print]",
@@ -149,7 +150,7 @@ func TestBashCompletions(t *testing.T) {
 	rootCmd.AddCommand(echoCmd, printCmd, deprecatedCmd, colonCmd)
 
 	buf := new(bytes.Buffer)
-	rootCmd.GenBashCompletion(buf)
+	er(rootCmd.GenBashCompletion(buf))
 	output := buf.String()
 
 	check(t, output, "_root")
@@ -209,10 +210,10 @@ func TestBashCompletionHiddenFlag(t *testing.T) {
 
 	const flagName = "hiddenFlag"
 	c.Flags().Bool(flagName, false, "")
-	c.Flags().MarkHidden(flagName)
+	er(c.Flags().MarkHidden(flagName))
 
 	buf := new(bytes.Buffer)
-	c.GenBashCompletion(buf)
+	er(c.GenBashCompletion(buf))
 	output := buf.String()
 
 	if strings.Contains(output, flagName) {
@@ -225,10 +226,10 @@ func TestBashCompletionDeprecatedFlag(t *testing.T) {
 
 	const flagName = "deprecated-flag"
 	c.Flags().Bool(flagName, false, "")
-	c.Flags().MarkDeprecated(flagName, "use --not-deprecated instead")
+	er(c.Flags().MarkDeprecated(flagName, "use --not-deprecated instead"))
 
 	buf := new(bytes.Buffer)
-	c.GenBashCompletion(buf)
+	er(c.GenBashCompletion(buf))
 	output := buf.String()
 
 	if strings.Contains(output, flagName) {
diff --git a/cobra.go b/cobra.go
index d01becc8f..00183ad7e 100644
--- a/cobra.go
+++ b/cobra.go
@@ -19,6 +19,7 @@ package cobra
 import (
 	"fmt"
 	"io"
+	"os"
 	"reflect"
 	"strconv"
 	"strings"
@@ -205,3 +206,18 @@ func stringInSlice(a string, list []string) bool {
 	}
 	return false
 }
+
+func er(msg interface{}) {
+	if msg != nil {
+		fmt.Println("Error:", msg)
+		os.Exit(1)
+	}
+}
+
+// Er prints the msg and exits with error code 1, unless the msg is nil
+func Er(msg interface{}) { er(msg) }
+
+func WrStringAndCheck(b io.StringWriter, s string) {
+	_, err := b.WriteString(s)
+	er(err)
+}
diff --git a/cobra/cmd/add.go b/cobra/cmd/add.go
index 6645a755f..f8c294718 100644
--- a/cobra/cmd/add.go
+++ b/cobra/cmd/add.go
@@ -40,7 +40,7 @@ Example: cobra add server -> resulting in a new cmd/server.go`,
 
 		Run: func(cmd *cobra.Command, args []string) {
 			if len(args) < 1 {
-				er("add needs a name for the command")
+				er(fmt.Errorf("add needs a name for the command"))
 			}
 
 			wd, err := os.Getwd()
@@ -72,7 +72,7 @@ Example: cobra add server -> resulting in a new cmd/server.go`,
 func init() {
 	addCmd.Flags().StringVarP(&packageName, "package", "t", "", "target package name (e.g. github.com/spf13/hugo)")
 	addCmd.Flags().StringVarP(&parentName, "parent", "p", "rootCmd", "variable name of parent command for this command")
-	addCmd.Flags().MarkDeprecated("package", "this operation has been removed.")
+	er(addCmd.Flags().MarkDeprecated("package", "this operation has been removed."))
 }
 
 // validateCmdName returns source without any dashes and underscore.
diff --git a/cobra/cmd/add_test.go b/cobra/cmd/add_test.go
index de92fcea6..2847a0649 100644
--- a/cobra/cmd/add_test.go
+++ b/cobra/cmd/add_test.go
@@ -14,10 +14,8 @@ func TestGoldenAddCmd(t *testing.T) {
 	}
 	defer os.RemoveAll(command.AbsolutePath)
 
-	command.Project.Create()
-	if err := command.Create(); err != nil {
-		t.Fatal(err)
-	}
+	er(command.Project.Create())
+	er(command.Create())
 
 	generatedFile := fmt.Sprintf("%s/cmd/%s.go", command.AbsolutePath, command.CmdName)
 	goldenFile := fmt.Sprintf("testdata/%s.go.golden", command.CmdName)
diff --git a/cobra/cmd/golden_test.go b/cobra/cmd/golden_test.go
index c030c6ab5..852ec4efe 100644
--- a/cobra/cmd/golden_test.go
+++ b/cobra/cmd/golden_test.go
@@ -3,14 +3,11 @@ package cmd
 import (
 	"bytes"
 	"errors"
-	"flag"
 	"fmt"
 	"io/ioutil"
 	"os/exec"
 )
 
-var update = flag.Bool("update", false, "update .golden files")
-
 func init() {
 	// Mute commands.
 	addCmd.SetOutput(new(bytes.Buffer))
@@ -56,27 +53,3 @@ func compareFiles(pathA, pathB string) error {
 	}
 	return nil
 }
-
-// checkLackFiles checks if all elements of expected are in got.
-func checkLackFiles(expected, got []string) error {
-	lacks := make([]string, 0, len(expected))
-	for _, ev := range expected {
-		if !stringInStringSlice(ev, got) {
-			lacks = append(lacks, ev)
-		}
-	}
-	if len(lacks) > 0 {
-		return fmt.Errorf("Lack %v file(s): %v", len(lacks), lacks)
-	}
-	return nil
-}
-
-// stringInStringSlice checks if s is an element of slice.
-func stringInStringSlice(s string, slice []string) bool {
-	for _, v := range slice {
-		if s == v {
-			return true
-		}
-	}
-	return false
-}
diff --git a/cobra/cmd/helpers.go b/cobra/cmd/helpers.go
index cd94b3e31..0f7c33ee5 100644
--- a/cobra/cmd/helpers.go
+++ b/cobra/cmd/helpers.go
@@ -14,14 +14,11 @@
 package cmd
 
 import (
-	"bytes"
 	"fmt"
-	"io"
 	"os"
 	"os/exec"
 	"path/filepath"
 	"strings"
-	"text/template"
 )
 
 var srcPaths []string
@@ -60,109 +57,8 @@ func init() {
 }
 
 func er(msg interface{}) {
-	fmt.Println("Error:", msg)
-	os.Exit(1)
-}
-
-// isEmpty checks if a given path is empty.
-// Hidden files in path are ignored.
-func isEmpty(path string) bool {
-	fi, err := os.Stat(path)
-	if err != nil {
-		er(err)
-	}
-
-	if !fi.IsDir() {
-		return fi.Size() == 0
-	}
-
-	f, err := os.Open(path)
-	if err != nil {
-		er(err)
-	}
-	defer f.Close()
-
-	names, err := f.Readdirnames(-1)
-	if err != nil && err != io.EOF {
-		er(err)
-	}
-
-	for _, name := range names {
-		if len(name) > 0 && name[0] != '.' {
-			return false
-		}
-	}
-	return true
-}
-
-// exists checks if a file or directory exists.
-func exists(path string) bool {
-	if path == "" {
-		return false
-	}
-	_, err := os.Stat(path)
-	if err == nil {
-		return true
-	}
-	if !os.IsNotExist(err) {
-		er(err)
-	}
-	return false
-}
-
-func executeTemplate(tmplStr string, data interface{}) (string, error) {
-	tmpl, err := template.New("").Funcs(template.FuncMap{"comment": commentifyString}).Parse(tmplStr)
-	if err != nil {
-		return "", err
-	}
-
-	buf := new(bytes.Buffer)
-	err = tmpl.Execute(buf, data)
-	return buf.String(), err
-}
-
-func writeStringToFile(path string, s string) error {
-	return writeToFile(path, strings.NewReader(s))
-}
-
-// writeToFile writes r to file with path only
-// if file/directory on given path doesn't exist.
-func writeToFile(path string, r io.Reader) error {
-	if exists(path) {
-		return fmt.Errorf("%v already exists", path)
-	}
-
-	dir := filepath.Dir(path)
-	if dir != "" {
-		if err := os.MkdirAll(dir, 0777); err != nil {
-			return err
-		}
-	}
-
-	file, err := os.Create(path)
-	if err != nil {
-		return err
-	}
-	defer file.Close()
-
-	_, err = io.Copy(file, r)
-	return err
-}
-
-// commentfyString comments every line of in.
-func commentifyString(in string) string {
-	var newlines []string
-	lines := strings.Split(in, "\n")
-	for _, line := range lines {
-		if strings.HasPrefix(line, "//") {
-			newlines = append(newlines, line)
-		} else {
-			if line == "" {
-				newlines = append(newlines, "//")
-			} else {
-				newlines = append(newlines, "// "+line)
-			}
-		}
+	if msg != nil {
+		fmt.Println("Error:", msg)
+		os.Exit(1)
 	}
-	return strings.Join(newlines, "\n")
 }
diff --git a/cobra/cmd/init.go b/cobra/cmd/init.go
index dcf5ada4f..c982ea4d1 100644
--- a/cobra/cmd/init.go
+++ b/cobra/cmd/init.go
@@ -74,5 +74,5 @@ Init will not use an existing directory with contents.`,
 
 func init() {
 	initCmd.Flags().StringVar(&pkgName, "pkg-name", "", "fully qualified pkg name")
-	initCmd.MarkFlagRequired("pkg-name")
+	er(initCmd.MarkFlagRequired("pkg-name"))
 }
diff --git a/cobra/cmd/init_test.go b/cobra/cmd/init_test.go
index 372dad024..0e09d90aa 100644
--- a/cobra/cmd/init_test.go
+++ b/cobra/cmd/init_test.go
@@ -34,9 +34,7 @@ func TestGoldenInitCmd(t *testing.T) {
 	project := getProject()
 	defer os.RemoveAll(project.AbsolutePath)
 
-	if err := project.Create(); err != nil {
-		t.Fatal(err)
-	}
+	er(project.Create())
 
 	expectedFiles := []string{"LICENSE", "main.go", "cmd/root.go"}
 	for _, f := range expectedFiles {
diff --git a/cobra/cmd/licenses.go b/cobra/cmd/licenses.go
index 5f5abc89a..e4e2ffeb8 100644
--- a/cobra/cmd/licenses.go
+++ b/cobra/cmd/licenses.go
@@ -16,6 +16,7 @@
 package cmd
 
 import (
+	"fmt"
 	"strings"
 	"time"
 
@@ -94,7 +95,7 @@ func copyrightLine() string {
 func findLicense(name string) License {
 	found := matchLicense(name)
 	if found == "" {
-		er("unknown license: " + name)
+		er(fmt.Errorf("unknown license: " + name))
 	}
 	return Licenses[found]
 }
diff --git a/cobra/cmd/project.go b/cobra/cmd/project.go
index b0c12e726..108ff52ad 100644
--- a/cobra/cmd/project.go
+++ b/cobra/cmd/project.go
@@ -49,7 +49,7 @@ func (p *Project) Create() error {
 
 	// create cmd/root.go
 	if _, err = os.Stat(fmt.Sprintf("%s/cmd", p.AbsolutePath)); os.IsNotExist(err) {
-		os.Mkdir(fmt.Sprintf("%s/cmd", p.AbsolutePath), 0751)
+		er(os.Mkdir(fmt.Sprintf("%s/cmd", p.AbsolutePath), 0751))
 	}
 	rootFile, err := os.Create(fmt.Sprintf("%s/cmd/root.go", p.AbsolutePath))
 	if err != nil {
diff --git a/cobra/cmd/root.go b/cobra/cmd/root.go
index 97f404bbb..27c7ac2a4 100644
--- a/cobra/cmd/root.go
+++ b/cobra/cmd/root.go
@@ -15,8 +15,8 @@ package cmd
 
 import (
 	"fmt"
+	"os"
 
-	homedir "github.com/mitchellh/go-homedir"
 	"github.com/spf13/cobra"
 	"github.com/spf13/viper"
 )
@@ -47,8 +47,8 @@ func init() {
 	rootCmd.PersistentFlags().StringP("author", "a", "YOUR NAME", "author name for copyright attribution")
 	rootCmd.PersistentFlags().StringVarP(&userLicense, "license", "l", "", "name of license for the project")
 	rootCmd.PersistentFlags().Bool("viper", true, "use Viper for configuration")
-	viper.BindPFlag("author", rootCmd.PersistentFlags().Lookup("author"))
-	viper.BindPFlag("useViper", rootCmd.PersistentFlags().Lookup("viper"))
+	er(viper.BindPFlag("author", rootCmd.PersistentFlags().Lookup("author")))
+	er(viper.BindPFlag("useViper", rootCmd.PersistentFlags().Lookup("viper")))
 	viper.SetDefault("author", "NAME HERE <EMAIL ADDRESS>")
 	viper.SetDefault("license", "apache")
 
@@ -62,7 +62,7 @@ func initConfig() {
 		viper.SetConfigFile(cfgFile)
 	} else {
 		// Find home directory.
-		home, err := homedir.Dir()
+		home, err := os.UserHomeDir()
 		if err != nil {
 			er(err)
 		}
diff --git a/cobra/cmd/testdata/root.go.golden b/cobra/cmd/testdata/root.go.golden
index 6a54a7837..618d8449c 100644
--- a/cobra/cmd/testdata/root.go.golden
+++ b/cobra/cmd/testdata/root.go.golden
@@ -17,10 +17,9 @@ package cmd
 
 import (
 	"fmt"
-	"github.com/spf13/cobra"
 	"os"
+	"github.com/spf13/cobra"
 
-	homedir "github.com/mitchellh/go-homedir"
 	"github.com/spf13/viper"
 )
 
@@ -38,7 +37,7 @@ This application is a tool to generate the needed files
 to quickly create a Cobra application.`,
 	// Uncomment the following line if your bare application
 	// has an action associated with it:
-	//	Run: func(cmd *cobra.Command, args []string) { },
+	// Run: func(cmd *cobra.Command, args []string) { },
 }
 
 // Execute adds all child commands to the root command and sets flags appropriately.
@@ -71,7 +70,7 @@ func initConfig() {
 		viper.SetConfigFile(cfgFile)
 	} else {
 		// Find home directory.
-		home, err := homedir.Dir()
+		home, err := os.UserHomeDir()
 		if err != nil {
 			fmt.Fprintln(os.Stderr, err)
 			os.Exit(1)
diff --git a/cobra/tpl/main.go b/cobra/tpl/main.go
index b5e2e1aeb..adc9b70b3 100644
--- a/cobra/tpl/main.go
+++ b/cobra/tpl/main.go
@@ -24,12 +24,10 @@ package cmd
 
 import (
 	"fmt"
-	"github.com/spf13/cobra"
 	"os"
+	"github.com/spf13/cobra"
 {{ if .Viper }}
-	homedir "github.com/mitchellh/go-homedir"
-	"github.com/spf13/viper"
-{{ end -}}
+	"github.com/spf13/viper"{{ end }}
 )
 
 {{ if .Viper -}}
@@ -48,7 +46,7 @@ This application is a tool to generate the needed files
 to quickly create a Cobra application.` + "`" + `,
 	// Uncomment the following line if your bare application
 	// has an action associated with it:
-	//	Run: func(cmd *cobra.Command, args []string) { },
+	// Run: func(cmd *cobra.Command, args []string) { },
 }
 
 // Execute adds all child commands to the root command and sets flags appropriately.
@@ -85,7 +83,7 @@ func initConfig() {
 		viper.SetConfigFile(cfgFile)
 	} else {
 		// Find home directory.
-		home, err := homedir.Dir()
+		home, err := os.UserHomeDir()
 		if err != nil {
 			fmt.Fprintln(os.Stderr, err)
 			os.Exit(1)
diff --git a/command.go b/command.go
index c2898ae8a..2f7e808b6 100644
--- a/command.go
+++ b/command.go
@@ -75,9 +75,6 @@ type Command struct {
 	// Deprecated defines, if this command is deprecated and should print this string when used.
 	Deprecated string
 
-	// Hidden defines, if this command is hidden and should NOT show up in the list of available commands.
-	Hidden bool
-
 	// Annotations are key/value pairs that can be used by applications to identify or
 	// group commands.
 	Annotations map[string]string
@@ -117,55 +114,6 @@ type Command struct {
 	// PersistentPostRunE: PersistentPostRun but returns an error.
 	PersistentPostRunE func(cmd *Command, args []string) error
 
-	// SilenceErrors is an option to quiet errors down stream.
-	SilenceErrors bool
-
-	// SilenceUsage is an option to silence usage when an error occurs.
-	SilenceUsage bool
-
-	// DisableFlagParsing disables the flag parsing.
-	// If this is true all flags will be passed to the command as arguments.
-	DisableFlagParsing bool
-
-	// DisableAutoGenTag defines, if gen tag ("Auto generated by spf13/cobra...")
-	// will be printed by generating docs for this command.
-	DisableAutoGenTag bool
-
-	// DisableFlagsInUseLine will disable the addition of [flags] to the usage
-	// line of a command when printing help or generating docs
-	DisableFlagsInUseLine bool
-
-	// DisableSuggestions disables the suggestions based on Levenshtein distance
-	// that go along with 'unknown command' messages.
-	DisableSuggestions bool
-	// SuggestionsMinimumDistance defines minimum levenshtein distance to display suggestions.
-	// Must be > 0.
-	SuggestionsMinimumDistance int
-
-	// TraverseChildren parses flags on all parents before executing child command.
-	TraverseChildren bool
-
-	// FParseErrWhitelist flag parse errors to be ignored
-	FParseErrWhitelist FParseErrWhitelist
-
-	ctx context.Context
-
-	// commands is the list of commands supported by this program.
-	commands []*Command
-	// parent is a parent command for this command.
-	parent *Command
-	// Max lengths of commands' string lengths for use in padding.
-	commandsMaxUseLen         int
-	commandsMaxCommandPathLen int
-	commandsMaxNameLen        int
-	// commandsAreSorted defines, if command slice are sorted or not.
-	commandsAreSorted bool
-	// commandCalledAs is the name or alias value used to call this command.
-	commandCalledAs struct {
-		name   string
-		called bool
-	}
-
 	// args is actual args parsed from flags.
 	args []string
 	// flagErrorBuf contains all error messages from pflag.
@@ -207,6 +155,60 @@ type Command struct {
 	outWriter io.Writer
 	// errWriter is a writer defined by the user that replaces stderr
 	errWriter io.Writer
+
+	//FParseErrWhitelist flag parse errors to be ignored
+	FParseErrWhitelist FParseErrWhitelist
+
+	// commandsAreSorted defines, if command slice are sorted or not.
+	commandsAreSorted bool
+	// commandCalledAs is the name or alias value used to call this command.
+	commandCalledAs struct {
+		name   string
+		called bool
+	}
+
+	ctx context.Context
+
+	// commands is the list of commands supported by this program.
+	commands []*Command
+	// parent is a parent command for this command.
+	parent *Command
+	// Max lengths of commands' string lengths for use in padding.
+	commandsMaxUseLen         int
+	commandsMaxCommandPathLen int
+	commandsMaxNameLen        int
+
+	// TraverseChildren parses flags on all parents before executing child command.
+	TraverseChildren bool
+
+	// Hidden defines, if this command is hidden and should NOT show up in the list of available commands.
+	Hidden bool
+
+	// SilenceErrors is an option to quiet errors down stream.
+	SilenceErrors bool
+
+	// SilenceUsage is an option to silence usage when an error occurs.
+	SilenceUsage bool
+
+	// DisableFlagParsing disables the flag parsing.
+	// If this is true all flags will be passed to the command as arguments.
+	DisableFlagParsing bool
+
+	// DisableAutoGenTag defines, if gen tag ("Auto generated by spf13/cobra...")
+	// will be printed by generating docs for this command.
+	DisableAutoGenTag bool
+
+	// DisableFlagsInUseLine will disable the addition of [flags] to the usage
+	// line of a command when printing help or generating docs
+	DisableFlagsInUseLine bool
+
+	// DisableSuggestions disables the suggestions based on Levenshtein distance
+	// that go along with 'unknown command' messages.
+	DisableSuggestions bool
+
+	// SuggestionsMinimumDistance defines minimum levenshtein distance to display suggestions.
+	// Must be > 0.
+	SuggestionsMinimumDistance int
 }
 
 // Context returns underlying command context. If command wasn't
@@ -409,7 +411,7 @@ func (c *Command) UsageString() string {
 	c.outWriter = bb
 	c.errWriter = bb
 
-	c.Usage()
+	er(c.Usage())
 
 	// Setting things back to normal
 	c.outWriter = tmpOutput
@@ -1064,10 +1066,10 @@ Simply type ` + c.Name() + ` help [path to command] for full details.`,
 				cmd, _, e := c.Root().Find(args)
 				if cmd == nil || e != nil {
 					c.Printf("Unknown help topic %#q\n", args)
-					c.Root().Usage()
+					er(c.Root().Usage())
 				} else {
 					cmd.InitDefaultHelpFlag() // make possible 'help' flag to be shown
-					cmd.Help()
+					er(cmd.Help())
 				}
 			},
 		}
diff --git a/command_test.go b/command_test.go
index 121559374..d0dbeeb0f 100644
--- a/command_test.go
+++ b/command_test.go
@@ -55,6 +55,8 @@ func checkStringOmits(t *testing.T, got, expected string) {
 	}
 }
 
+const onetwo = "one two"
+
 func TestSingleCommand(t *testing.T) {
 	var rootCmdArgs []string
 	rootCmd := &Command{
@@ -75,9 +77,8 @@ func TestSingleCommand(t *testing.T) {
 	}
 
 	got := strings.Join(rootCmdArgs, " ")
-	expected := "one two"
-	if got != expected {
-		t.Errorf("rootCmdArgs expected: %q, got: %q", expected, got)
+	if got != onetwo {
+		t.Errorf("rootCmdArgs expected: %q, got: %q", onetwo, got)
 	}
 }
 
@@ -101,9 +102,8 @@ func TestChildCommand(t *testing.T) {
 	}
 
 	got := strings.Join(child1CmdArgs, " ")
-	expected := "one two"
-	if got != expected {
-		t.Errorf("child1CmdArgs expected: %q, got: %q", expected, got)
+	if got != onetwo {
+		t.Errorf("child1CmdArgs expected: %q, got: %q", onetwo, got)
 	}
 }
 
@@ -142,7 +142,7 @@ func TestSubcommandExecuteC(t *testing.T) {
 	}
 
 	if c.Name() != "child" {
-		t.Errorf(`invalid command returned from ExecuteC: expected "child"', got %q`, c.Name())
+		t.Errorf(`invalid command returned from ExecuteC: expected "child"', got: %q`, c.Name())
 	}
 }
 
@@ -240,9 +240,8 @@ func TestCommandAlias(t *testing.T) {
 	}
 
 	got := strings.Join(timesCmdArgs, " ")
-	expected := "one two"
-	if got != expected {
-		t.Errorf("timesCmdArgs expected: %v, got: %v", expected, got)
+	if got != onetwo {
+		t.Errorf("timesCmdArgs expected: %v, got: %v", onetwo, got)
 	}
 }
 
@@ -268,9 +267,8 @@ func TestEnablePrefixMatching(t *testing.T) {
 	}
 
 	got := strings.Join(aCmdArgs, " ")
-	expected := "one two"
-	if got != expected {
-		t.Errorf("aCmdArgs expected: %q, got: %q", expected, got)
+	if got != onetwo {
+		t.Errorf("aCmdArgs expected: %q, got: %q", onetwo, got)
 	}
 
 	EnablePrefixMatching = false
@@ -304,9 +302,8 @@ func TestAliasPrefixMatching(t *testing.T) {
 	}
 
 	got := strings.Join(timesCmdArgs, " ")
-	expected := "one two"
-	if got != expected {
-		t.Errorf("timesCmdArgs expected: %v, got: %v", expected, got)
+	if got != onetwo {
+		t.Errorf("timesCmdArgs expected: %v, got: %v", onetwo, got)
 	}
 
 	EnablePrefixMatching = false
@@ -335,9 +332,8 @@ func TestChildSameName(t *testing.T) {
 	}
 
 	got := strings.Join(fooCmdArgs, " ")
-	expected := "one two"
-	if got != expected {
-		t.Errorf("fooCmdArgs expected: %v, got: %v", expected, got)
+	if got != onetwo {
+		t.Errorf("fooCmdArgs expected: %v, got: %v", onetwo, got)
 	}
 }
 
@@ -365,9 +361,8 @@ func TestGrandChildSameName(t *testing.T) {
 	}
 
 	got := strings.Join(fooCmdArgs, " ")
-	expected := "one two"
-	if got != expected {
-		t.Errorf("fooCmdArgs expected: %v, got: %v", expected, got)
+	if got != onetwo {
+		t.Errorf("fooCmdArgs expected: %v, got: %v", onetwo, got)
 	}
 }
 
@@ -403,9 +398,8 @@ func TestFlagLong(t *testing.T) {
 	}
 
 	got := strings.Join(cArgs, " ")
-	expected := "one two"
-	if got != expected {
-		t.Errorf("Expected arguments: %q, got %q", expected, got)
+	if got != onetwo {
+		t.Errorf("rootCmdArgs expected: %q, got: %q", onetwo, got)
 	}
 }
 
@@ -438,9 +432,8 @@ func TestFlagShort(t *testing.T) {
 	}
 
 	got := strings.Join(cArgs, " ")
-	expected := "one two"
-	if got != expected {
-		t.Errorf("Expected arguments: %q, got %q", expected, got)
+	if got != onetwo {
+		t.Errorf("rootCmdArgs expected: %q, got: %q", onetwo, got)
 	}
 }
 
@@ -642,9 +635,8 @@ func TestPersistentFlagsOnSameCommand(t *testing.T) {
 	}
 
 	got := strings.Join(rootCmdArgs, " ")
-	expected := "one two"
-	if got != expected {
-		t.Errorf("rootCmdArgs expected: %q, got %q", expected, got)
+	if got != onetwo {
+		t.Errorf("rootCmdArgs expected: %q, got %q", onetwo, got)
 	}
 	if flagValue != 7 {
 		t.Errorf("flagValue expected: %v, got %v", 7, flagValue)
@@ -728,9 +720,8 @@ func TestPersistentFlagsOnChild(t *testing.T) {
 	}
 
 	got := strings.Join(childCmdArgs, " ")
-	expected := "one two"
-	if got != expected {
-		t.Errorf("childCmdArgs expected: %q, got %q", expected, got)
+	if got != onetwo {
+		t.Errorf("rootCmdArgs expected: %q, got: %q", onetwo, got)
 	}
 	if parentFlagValue != 8 {
 		t.Errorf("parentFlagValue expected: %v, got %v", 8, parentFlagValue)
@@ -743,9 +734,9 @@ func TestPersistentFlagsOnChild(t *testing.T) {
 func TestRequiredFlags(t *testing.T) {
 	c := &Command{Use: "c", Run: emptyRun}
 	c.Flags().String("foo1", "", "")
-	c.MarkFlagRequired("foo1")
+	er(c.MarkFlagRequired("foo1"))
 	c.Flags().String("foo2", "", "")
-	c.MarkFlagRequired("foo2")
+	er(c.MarkFlagRequired("foo2"))
 	c.Flags().String("bar", "", "")
 
 	expected := fmt.Sprintf("required flag(s) %q, %q not set", "foo1", "foo2")
@@ -761,16 +752,16 @@ func TestRequiredFlags(t *testing.T) {
 func TestPersistentRequiredFlags(t *testing.T) {
 	parent := &Command{Use: "parent", Run: emptyRun}
 	parent.PersistentFlags().String("foo1", "", "")
-	parent.MarkPersistentFlagRequired("foo1")
+	er(parent.MarkPersistentFlagRequired("foo1"))
 	parent.PersistentFlags().String("foo2", "", "")
-	parent.MarkPersistentFlagRequired("foo2")
+	er(parent.MarkPersistentFlagRequired("foo2"))
 	parent.Flags().String("foo3", "", "")
 
 	child := &Command{Use: "child", Run: emptyRun}
 	child.Flags().String("bar1", "", "")
-	child.MarkFlagRequired("bar1")
+	er(child.MarkFlagRequired("bar1"))
 	child.Flags().String("bar2", "", "")
-	child.MarkFlagRequired("bar2")
+	er(child.MarkFlagRequired("bar2"))
 	child.Flags().String("bar3", "", "")
 
 	parent.AddCommand(child)
@@ -1265,20 +1256,19 @@ func TestHooks(t *testing.T) {
 		t.Errorf("Unexpected error: %v", err)
 	}
 
-	if persPreArgs != "one two" {
-		t.Errorf("Expected persPreArgs %q, got %q", "one two", persPreArgs)
-	}
-	if preArgs != "one two" {
-		t.Errorf("Expected preArgs %q, got %q", "one two", preArgs)
-	}
-	if runArgs != "one two" {
-		t.Errorf("Expected runArgs %q, got %q", "one two", runArgs)
-	}
-	if postArgs != "one two" {
-		t.Errorf("Expected postArgs %q, got %q", "one two", postArgs)
-	}
-	if persPostArgs != "one two" {
-		t.Errorf("Expected persPostArgs %q, got %q", "one two", persPostArgs)
+	for _, v := range []struct {
+		name string
+		got  string
+	}{
+		{"persPreArgs", persPreArgs},
+		{"preArgs", preArgs},
+		{"runArgs", runArgs},
+		{"postArgs", postArgs},
+		{"persPostArgs", persPostArgs},
+	} {
+		if v.got != onetwo {
+			t.Errorf("Expected %s %q, got %q", v.name, onetwo, v.got)
+		}
 	}
 }
 
@@ -1346,44 +1336,42 @@ func TestPersistentHooks(t *testing.T) {
 		t.Errorf("Unexpected error: %v", err)
 	}
 
-	// TODO: currently PersistenPreRun* defined in parent does not
-	// run if the matchin child subcommand has PersistenPreRun.
-	// If the behavior changes (https://github.com/spf13/cobra/issues/252)
-	// this test must be fixed.
-	if parentPersPreArgs != "" {
-		t.Errorf("Expected blank parentPersPreArgs, got %q", parentPersPreArgs)
-	}
-	if parentPreArgs != "" {
-		t.Errorf("Expected blank parentPreArgs, got %q", parentPreArgs)
-	}
-	if parentRunArgs != "" {
-		t.Errorf("Expected blank parentRunArgs, got %q", parentRunArgs)
-	}
-	if parentPostArgs != "" {
-		t.Errorf("Expected blank parentPostArgs, got %q", parentPostArgs)
-	}
-	// TODO: currently PersistenPostRun* defined in parent does not
-	// run if the matchin child subcommand has PersistenPostRun.
-	// If the behavior changes (https://github.com/spf13/cobra/issues/252)
-	// this test must be fixed.
-	if parentPersPostArgs != "" {
-		t.Errorf("Expected blank parentPersPostArgs, got %q", parentPersPostArgs)
+	for _, v := range []struct {
+		name string
+		got  string
+	}{
+		// TODO: currently PersistenPreRun* defined in parent does not
+		// run if the matchin child subcommand has PersistenPreRun.
+		// If the behavior changes (https://github.com/spf13/cobra/issues/252)
+		// this test must be fixed.
+		{"parentPersPreArgs", parentPersPreArgs},
+		{"parentPreArgs", parentPreArgs},
+		{"parentRunArgs", parentRunArgs},
+		{"parentPostArgs", parentPostArgs},
+		// TODO: currently PersistenPostRun* defined in parent does not
+		// run if the matchin child subcommand has PersistenPostRun.
+		// If the behavior changes (https://github.com/spf13/cobra/issues/252)
+		// this test must be fixed.
+		{"parentPersPostArgs", parentPersPostArgs},
+	} {
+		if v.got != "" {
+			t.Errorf("Expected blank %s, got %q", v.name, v.got)
+		}
 	}
 
-	if childPersPreArgs != "one two" {
-		t.Errorf("Expected childPersPreArgs %q, got %q", "one two", childPersPreArgs)
-	}
-	if childPreArgs != "one two" {
-		t.Errorf("Expected childPreArgs %q, got %q", "one two", childPreArgs)
-	}
-	if childRunArgs != "one two" {
-		t.Errorf("Expected childRunArgs %q, got %q", "one two", childRunArgs)
-	}
-	if childPostArgs != "one two" {
-		t.Errorf("Expected childPostArgs %q, got %q", "one two", childPostArgs)
-	}
-	if childPersPostArgs != "one two" {
-		t.Errorf("Expected childPersPostArgs %q, got %q", "one two", childPersPostArgs)
+	for _, v := range []struct {
+		name string
+		got  string
+	}{
+		{"childPersPreArgs", childPersPreArgs},
+		{"childPreArgs", childPreArgs},
+		{"childRunArgs", childRunArgs},
+		{"childPostArgs", childPostArgs},
+		{"childPersPostArgs", childPersPostArgs},
+	} {
+		if v.got != onetwo {
+			t.Errorf("Expected %s %q, got %q", v.name, onetwo, v.got)
+		}
 	}
 }
 
@@ -1666,7 +1654,7 @@ func TestMergeCommandLineToFlags(t *testing.T) {
 func TestUseDeprecatedFlags(t *testing.T) {
 	c := &Command{Use: "c", Run: emptyRun}
 	c.Flags().BoolP("deprecated", "d", false, "deprecated flag")
-	c.Flags().MarkDeprecated("deprecated", "This flag is deprecated")
+	er(c.Flags().MarkDeprecated("deprecated", "This flag is deprecated"))
 
 	output, err := executeCommand(c, "c", "-d")
 	if err != nil {
@@ -1793,7 +1781,6 @@ type calledAsTestcase struct {
 	call string
 	want string
 	epm  bool
-	tc   bool
 }
 
 func (tc *calledAsTestcase) test(t *testing.T) {
@@ -1814,7 +1801,7 @@ func (tc *calledAsTestcase) test(t *testing.T) {
 	output := new(bytes.Buffer)
 	parent.SetOutput(output)
 
-	parent.Execute()
+	_ = parent.Execute()
 
 	if called == nil {
 		if tc.call != "" {
@@ -1832,18 +1819,18 @@ func (tc *calledAsTestcase) test(t *testing.T) {
 
 func TestCalledAs(t *testing.T) {
 	tests := map[string]calledAsTestcase{
-		"find/no-args":            {nil, "parent", "parent", false, false},
-		"find/real-name":          {[]string{"child1"}, "child1", "child1", false, false},
-		"find/full-alias":         {[]string{"that"}, "child2", "that", false, false},
-		"find/part-no-prefix":     {[]string{"thi"}, "", "", false, false},
-		"find/part-alias":         {[]string{"thi"}, "child1", "this", true, false},
-		"find/conflict":           {[]string{"th"}, "", "", true, false},
-		"traverse/no-args":        {nil, "parent", "parent", false, true},
-		"traverse/real-name":      {[]string{"child1"}, "child1", "child1", false, true},
-		"traverse/full-alias":     {[]string{"that"}, "child2", "that", false, true},
-		"traverse/part-no-prefix": {[]string{"thi"}, "", "", false, true},
-		"traverse/part-alias":     {[]string{"thi"}, "child1", "this", true, true},
-		"traverse/conflict":       {[]string{"th"}, "", "", true, true},
+		"find/no-args":            {nil, "parent", "parent", false},
+		"find/real-name":          {[]string{"child1"}, "child1", "child1", false},
+		"find/full-alias":         {[]string{"that"}, "child2", "that", false},
+		"find/part-no-prefix":     {[]string{"thi"}, "", "", false},
+		"find/part-alias":         {[]string{"thi"}, "child1", "this", true},
+		"find/conflict":           {[]string{"th"}, "", "", true},
+		"traverse/no-args":        {nil, "parent", "parent", false},
+		"traverse/real-name":      {[]string{"child1"}, "child1", "child1", false},
+		"traverse/full-alias":     {[]string{"that"}, "child2", "that", false},
+		"traverse/part-no-prefix": {[]string{"thi"}, "", "", false},
+		"traverse/part-alias":     {[]string{"thi"}, "child1", "this", true},
+		"traverse/conflict":       {[]string{"th"}, "", "", true},
 	}
 
 	for name, tc := range tests {
diff --git a/doc/man_docs.go b/doc/man_docs.go
index 8c7fba44a..817070f9e 100644
--- a/doc/man_docs.go
+++ b/doc/man_docs.go
@@ -139,25 +139,25 @@ func fillHeader(header *GenManHeader, name string) error {
 	return nil
 }
 
-func manPreamble(buf *bytes.Buffer, header *GenManHeader, cmd *cobra.Command, dashedName string) {
+func manPreamble(buf io.StringWriter, header *GenManHeader, cmd *cobra.Command, dashedName string) {
 	description := cmd.Long
 	if len(description) == 0 {
 		description = cmd.Short
 	}
 
-	buf.WriteString(fmt.Sprintf(`%% %s(%s)%s
+	wrStringAndCheck(buf, fmt.Sprintf(`%% %s(%s)%s
 %% %s
 %% %s
 # NAME
 `, header.Title, header.Section, header.date, header.Source, header.Manual))
-	buf.WriteString(fmt.Sprintf("%s \\- %s\n\n", dashedName, cmd.Short))
-	buf.WriteString("# SYNOPSIS\n")
-	buf.WriteString(fmt.Sprintf("**%s**\n\n", cmd.UseLine()))
-	buf.WriteString("# DESCRIPTION\n")
-	buf.WriteString(description + "\n\n")
+	wrStringAndCheck(buf, fmt.Sprintf("%s \\- %s\n\n", dashedName, cmd.Short))
+	wrStringAndCheck(buf, "# SYNOPSIS\n")
+	wrStringAndCheck(buf, fmt.Sprintf("**%s**\n\n", cmd.UseLine()))
+	wrStringAndCheck(buf, "# DESCRIPTION\n")
+	wrStringAndCheck(buf, description+"\n\n")
 }
 
-func manPrintFlags(buf *bytes.Buffer, flags *pflag.FlagSet) {
+func manPrintFlags(buf io.StringWriter, flags *pflag.FlagSet) {
 	flags.VisitAll(func(flag *pflag.Flag) {
 		if len(flag.Deprecated) > 0 || flag.Hidden {
 			return
@@ -181,22 +181,22 @@ func manPrintFlags(buf *bytes.Buffer, flags *pflag.FlagSet) {
 			format += "]"
 		}
 		format += "\n\t%s\n\n"
-		buf.WriteString(fmt.Sprintf(format, flag.DefValue, flag.Usage))
+		wrStringAndCheck(buf, fmt.Sprintf(format, flag.DefValue, flag.Usage))
 	})
 }
 
-func manPrintOptions(buf *bytes.Buffer, command *cobra.Command) {
+func manPrintOptions(buf io.StringWriter, command *cobra.Command) {
 	flags := command.NonInheritedFlags()
 	if flags.HasAvailableFlags() {
-		buf.WriteString("# OPTIONS\n")
+		wrStringAndCheck(buf, "# OPTIONS\n")
 		manPrintFlags(buf, flags)
-		buf.WriteString("\n")
+		wrStringAndCheck(buf, "\n")
 	}
 	flags = command.InheritedFlags()
 	if flags.HasAvailableFlags() {
-		buf.WriteString("# OPTIONS INHERITED FROM PARENT COMMANDS\n")
+		wrStringAndCheck(buf, "# OPTIONS INHERITED FROM PARENT COMMANDS\n")
 		manPrintFlags(buf, flags)
-		buf.WriteString("\n")
+		wrStringAndCheck(buf, "\n")
 	}
 }
 
diff --git a/doc/man_docs_test.go b/doc/man_docs_test.go
index 2c400f5df..609afdc6e 100644
--- a/doc/man_docs_test.go
+++ b/doc/man_docs_test.go
@@ -131,7 +131,7 @@ func TestGenManSeeAlso(t *testing.T) {
 func TestManPrintFlagsHidesShortDeperecated(t *testing.T) {
 	c := &cobra.Command{}
 	c.Flags().StringP("foo", "f", "default", "Foo flag")
-	c.Flags().MarkShorthandDeprecated("foo", "don't use it no more")
+	er(c.Flags().MarkShorthandDeprecated("foo", "don't use it no more"))
 
 	buf := new(bytes.Buffer)
 	manPrintFlags(buf, c.Flags())
diff --git a/doc/man_examples_test.go b/doc/man_examples_test.go
index db6604268..58dee8a8c 100644
--- a/doc/man_examples_test.go
+++ b/doc/man_examples_test.go
@@ -8,6 +8,10 @@ import (
 	"github.com/spf13/cobra/doc"
 )
 
+func er(msg interface{}) {
+	cobra.Er(msg)
+}
+
 func ExampleGenManTree() {
 	cmd := &cobra.Command{
 		Use:   "test",
@@ -17,7 +21,7 @@ func ExampleGenManTree() {
 		Title:   "MINE",
 		Section: "3",
 	}
-	doc.GenManTree(cmd, header, "/tmp")
+	er(doc.GenManTree(cmd, header, "/tmp"))
 }
 
 func ExampleGenMan() {
@@ -30,6 +34,6 @@ func ExampleGenMan() {
 		Section: "3",
 	}
 	out := new(bytes.Buffer)
-	doc.GenMan(cmd, header, out)
+	er(doc.GenMan(cmd, header, out))
 	fmt.Print(out.String())
 }
diff --git a/doc/util.go b/doc/util.go
index 8d3dbecec..584780694 100644
--- a/doc/util.go
+++ b/doc/util.go
@@ -14,6 +14,7 @@
 package doc
 
 import (
+	"io"
 	"strings"
 
 	"github.com/spf13/cobra"
@@ -49,3 +50,11 @@ type byName []*cobra.Command
 func (s byName) Len() int           { return len(s) }
 func (s byName) Swap(i, j int)      { s[i], s[j] = s[j], s[i] }
 func (s byName) Less(i, j int) bool { return s[i].Name() < s[j].Name() }
+
+func er(msg interface{}) {
+	cobra.Er(msg)
+}
+
+func wrStringAndCheck(b io.StringWriter, s string) {
+	cobra.WrStringAndCheck(b, s)
+}
diff --git a/go.mod b/go.mod
index a552b01a3..dd7d02eb9 100644
--- a/go.mod
+++ b/go.mod
@@ -5,7 +5,6 @@ go 1.12
 require (
 	github.com/cpuguy83/go-md2man/v2 v2.0.0
 	github.com/inconshreveable/mousetrap v1.0.0
-	github.com/mitchellh/go-homedir v1.1.0
 	github.com/spf13/pflag v1.0.5
 	github.com/spf13/viper v1.6.2
 	gopkg.in/yaml.v2 v2.2.8
diff --git a/go.sum b/go.sum
index 0c081e45e..bf5b224a7 100644
--- a/go.sum
+++ b/go.sum
@@ -62,8 +62,6 @@ github.com/kr/text v0.1.0/go.mod h1:4Jbv+DJW3UT/LiOwJeYQe1efqtUx/iVham/4vfdArNI=
 github.com/magiconair/properties v1.8.1 h1:ZC2Vc7/ZFkGmsVC9KvOjumD+G5lXy2RtTKyzRKO2BQ4=
 github.com/magiconair/properties v1.8.1/go.mod h1:PppfXfuXeibc/6YijjN8zIbojt8czPbwD3XqdrwzmxQ=
 github.com/matttproud/golang_protobuf_extensions v1.0.1/go.mod h1:D8He9yQNgCq6Z5Ld7szi9bcBfOoFv/3dc6xSMkL2PC0=
-github.com/mitchellh/go-homedir v1.1.0 h1:lukF9ziXFxDFPkA1vsr5zpc1XuPDn/wFntq5mG+4E0Y=
-github.com/mitchellh/go-homedir v1.1.0/go.mod h1:SfyaCUpYCn1Vlf4IUYiD9fPX4A5wJrkLzIz1N1q0pr0=
 github.com/mitchellh/mapstructure v1.1.2 h1:fmNYVwqnSfB9mZU6OS2O6GsXM+wcskZDuKQzvN1EDeE=
 github.com/mitchellh/mapstructure v1.1.2/go.mod h1:FVVH3fgwuzCH5S8UJGiWEs2h04kUh9fWfEaFds41c1Y=
 github.com/mwitkow/go-conntrack v0.0.0-20161129095857-cc309e4a2223/go.mod h1:qRWi+5nqEBWmkhHvq77mSJWrCKwh8bxhgT7d/eI7P4U=
diff --git a/powershell_completions_test.go b/powershell_completions_test.go
index 29b609de0..0a8c837df 100644
--- a/powershell_completions_test.go
+++ b/powershell_completions_test.go
@@ -109,7 +109,7 @@ func TestPowerShellCompletion(t *testing.T) {
 	for _, tc := range tcs {
 		t.Run(tc.name, func(t *testing.T) {
 			buf := new(bytes.Buffer)
-			tc.root.GenPowerShellCompletion(buf)
+			er(tc.root.GenPowerShellCompletion(buf))
 			output := buf.String()
 
 			for _, expectedExpression := range tc.expectedExpressions {
diff --git a/zsh_completions_test.go b/zsh_completions_test.go
index e53fa886e..dc6571b4e 100644
--- a/zsh_completions_test.go
+++ b/zsh_completions_test.go
@@ -90,9 +90,9 @@ func TestGenZshCompletion(t *testing.T) {
 					Run:   emptyRun,
 				}
 				r.Flags().StringVarP(&file, "config", "c", file, "config file")
-				r.MarkFlagFilename("config")
+				er(r.MarkFlagFilename("config"))
 				r.Flags().String("output", "", "output file")
-				r.MarkFlagFilename("output", "*.log", "*.txt")
+				er(r.MarkFlagFilename("output", "*.log", "*.txt"))
 				return r
 			}(),
 			expectedExpressions: []string{
@@ -161,8 +161,8 @@ func TestGenZshCompletion(t *testing.T) {
 			name: "argument completion for file with and without patterns",
 			root: func() *Command {
 				r := genTestCommand("root", true)
-				r.MarkZshCompPositionalArgumentFile(1, "*.log")
-				r.MarkZshCompPositionalArgumentFile(2)
+				er(r.MarkZshCompPositionalArgumentFile(1, "*.log"))
+				er(r.MarkZshCompPositionalArgumentFile(2))
 				return r
 			}(),
 			expectedExpressions: []string{
@@ -173,7 +173,7 @@ func TestGenZshCompletion(t *testing.T) {
 			name: "argument zsh completion for words",
 			root: func() *Command {
 				r := genTestCommand("root", true)
-				r.MarkZshCompPositionalArgumentWords(1, "word1", "word2")
+				er(r.MarkZshCompPositionalArgumentWords(1, "word1", "word2"))
 				return r
 			}(),
 			expectedExpressions: []string{
@@ -184,7 +184,7 @@ func TestGenZshCompletion(t *testing.T) {
 			name: "argument completion for words with spaces",
 			root: func() *Command {
 				r := genTestCommand("root", true)
-				r.MarkZshCompPositionalArgumentWords(1, "single", "multiple words")
+				er(r.MarkZshCompPositionalArgumentWords(1, "single", "multiple words"))
 				return r
 			}(),
 			expectedExpressions: []string{
@@ -207,7 +207,7 @@ func TestGenZshCompletion(t *testing.T) {
 			root: func() *Command {
 				r := genTestCommand("root", true)
 				r.ValidArgs = []string{"word1", "word2"}
-				r.MarkZshCompPositionalArgumentFile(2)
+				er(r.MarkZshCompPositionalArgumentFile(2))
 				return r
 			}(),
 			expectedExpressions: []string{
@@ -220,8 +220,8 @@ func TestGenZshCompletion(t *testing.T) {
 				r := genTestCommand("root", true)
 				r.Flags().String("test", "", "test")
 				r.PersistentFlags().String("ptest", "", "ptest")
-				r.MarkFlagDirname("test")
-				r.MarkPersistentFlagDirname("ptest")
+				er(r.MarkFlagDirname("test"))
+				er(r.MarkPersistentFlagDirname("ptest"))
 				return r
 			}(),
 			expectedExpressions: []string{
@@ -237,7 +237,7 @@ func TestGenZshCompletion(t *testing.T) {
 				t.Skip(tc.skip)
 			}
 			tc.root.Root().SetArgs(tc.invocationArgs)
-			tc.root.Execute()
+			_ = tc.root.Execute()
 			buf := new(bytes.Buffer)
 			if err := tc.root.GenZshCompletion(buf); err != nil {
 				t.Error(err)
@@ -311,11 +311,9 @@ func TestGenZshCompletionHidden(t *testing.T) {
 
 	for _, tc := range tcs {
 		t.Run(tc.name, func(t *testing.T) {
-			tc.root.Execute()
+			_ = tc.root.Execute()
 			buf := new(bytes.Buffer)
-			if err := tc.root.GenZshCompletion(buf); err != nil {
-				t.Error(err)
-			}
+			er(tc.root.GenZshCompletion(buf))
 			output := buf.String()
 
 			for _, expr := range tc.expectedExpressions {
@@ -457,7 +455,7 @@ func constructLargeCommandHierarchy() *Command {
 	s1.AddCommand(s1_1, s1_2, s1_3)
 	s2.AddCommand(s2_1, s2_2, s2_3, s2_4, s2_5)
 	r.AddCommand(s1, s2, s3)
-	r.Execute()
+	er(r.Execute())
 	return r
 }