Change format switch from 'linux' to 'unix' to match the readme

- Fixing -n not being parsed by CLI
- fmt -n will error on any duplicates or conflicts
- fmt (without -n) will NOT error on duplicates; it will simply replace them
- fmt (without -n) WILL error on conflicts, since it does not know how to fix them
- fmt will exit 1 when an error state is reached

.gitignore

@@ -1,2 +1,3 @@
 /.idea/
 /bin/
+.DS_Store

.travis.yml

@@ -1,7 +1,8 @@
+dist: bionic
 language: go
 
 go:
-    - 1.14
+    - 1.14.x
 
 notifications:
     email: false

CHANGELOG.md

@@ -1,5 +1,32 @@
 # Change Log
 
+## v0.5.2 (March 13, 2020)
+
+Bug Fixes
+
+- `hostess fmt -n` works properly again, and has more specific behavior:
+- `hostess fmt` will replace duplicates without asking for help
+- `hostess fmt -n` will *not* replace duplicates, and will exit with error if any are found (#41)
+- `hostess fmt` with and without `-n` will exit with error if conflicting hostnames are found because hostess cannot fix the conflicts
+
+## v0.5.1 (March 10, 2020)
+
+Bug Fixes
+
+- Format will no longer exit with an error when encountering a duplicate entry (#39)
+
+## v0.5.0 (March 7, 2020)
+
+Breaking changes
+
+- Windows now has a platform-specific hosts format with one IP and hostname per line
+
+## v0.4.1 (February 28, 2020)
+
+Bug Fixes
+
+- Fix hostfiles not saving on Windows #27
+
 ## v0.4.0 (February 28, 2020)
 
 0.4.0 is a major refactor of the frontend (CLI) focused on simplifying the UI

README.md

@@ -60,11 +60,9 @@ hostess may be configured via environment variables.
 
 ## IPv4 and IPv6
 
-Your hosts file _may_ contain overlapping entries where the same hostname points
-to both an IPv4 and IPv6 IP. In this case, hostess commands will apply to both
-entries. Typically you won't have this kind of overlap and the default behavior
-is OK. However, if you need to be more granular you can use `-4` or `-6` to
-limit operations to entries associated with that type of IP.
+It's possible for your hosts file to include overlapping entries for IPv4 and
+IPv6. This is an uncommon case so the CLI ignores this distinction. The hostess
+library includes logic that differentiates between these cases.
 
 ## Contributing
 

commands.go

@@ -11,14 +11,10 @@ import (
 	"github.com/cbednarski/hostess/hostess"
 )
 
-const (
-	IPv4 = 1 << iota
-	IPv6 = 1 << iota
-)
+var ErrParsingHostsFile = errors.New("Errors while parsing hostsfile. Please resolve any conflicts and try again.")
 
 type Options struct {
-	IPVersion int
-	Preview   bool
+	Preview bool
 }
 
 // PrintErrLn will print to stderr followed by a newline
@@ -27,18 +23,30 @@ func PrintErrLn(err error) {
 }
 
 // LoadHostfile will try to load, parse, and return a Hostfile. If we
-// encounter errors we will terminate, unless -f is passed.
-func LoadHostfile() (*hostess.Hostfile, error) {
+// encounter errors we will terminate.
+func LoadHostfile(options *Options) (*hostess.Hostfile, error) {
 	hosts, errs := hostess.LoadHostfile()
 
+	var err error
+
 	if len(errs) > 0 {
-		for _, err := range errs {
-			PrintErrLn(err)
+		// If -n is passed, we'll always exit with an error code on duplicate.
+		// See issue 39
+		if options.Preview {
+			err = ErrParsingHostsFile
+		}
+
+		for _, currentErr := range errs {
+			PrintErrLn(currentErr)
+			// If we find a duplicate we'll notify the user and continue. For
+			// other errors we'll bail out.
+			if !strings.Contains(currentErr.Error(), "duplicate hostname entry") {
+				err = ErrParsingHostsFile
+			}
 		}
-		return nil, errors.New("Errors while parsing hostsfile. Please fix any dupes or conflicts and try again.")
 	}
 
-	return hosts, nil
+	return hosts, err
 }
 
 // SaveOrPreview will display or write the Hostfile
@@ -70,7 +78,7 @@ func StrPadRight(input string, length int) string {
 // Add command parses <hostname> <ip> and adds or updates a hostname in the
 // hosts file
 func Add(options *Options, hostname, ip string) error {
-	hostsfile, err := LoadHostfile()
+	hostsfile, err := LoadHostfile(options)
 
 	newHostname, err := hostess.NewHostname(hostname, ip, true)
 	if err != nil {
@@ -103,7 +111,7 @@ func Add(options *Options, hostname, ip string) error {
 
 // Remove command removes any hostname(s) matching <domain> from the hosts file
 func Remove(options *Options, hostname string) error {
-	hostsfile, err := LoadHostfile()
+	hostsfile, err := LoadHostfile(options)
 	if err != nil {
 		return err
 	}
@@ -124,7 +132,7 @@ func Remove(options *Options, hostname string) error {
 
 // Has command indicates whether a hostname is present in the hosts file
 func Has(options *Options, hostname string) error {
-	hostsfile, err := LoadHostfile()
+	hostsfile, err := LoadHostfile(options)
 	if err != nil {
 		return err
 	}
@@ -141,7 +149,7 @@ func Has(options *Options, hostname string) error {
 }
 
 func Enable(options *Options, hostname string) error {
-	hostsfile, err := LoadHostfile()
+	hostsfile, err := LoadHostfile(options)
 	if err != nil {
 		return err
 	}
@@ -160,7 +168,7 @@ func Enable(options *Options, hostname string) error {
 }
 
 func Disable(options *Options, hostname string) error {
-	hostsfile, err := LoadHostfile()
+	hostsfile, err := LoadHostfile(options)
 	if err != nil {
 		return err
 	}
@@ -187,7 +195,7 @@ func Disable(options *Options, hostname string) error {
 
 // List command shows a list of hostnames in the hosts file
 func List(options *Options) error {
-	hostsfile, err := LoadHostfile()
+	hostsfile, err := LoadHostfile(options)
 	if err != nil {
 		return err
 	}
@@ -216,9 +224,9 @@ func List(options *Options) error {
 	return nil
 }
 
-// Format command removes duplicates and conflicts from the hosts file
+// Format command removes duplicates from the hosts file
 func Format(options *Options) error {
-	hostsfile, err := LoadHostfile()
+	hostsfile, err := LoadHostfile(options)
 	if err != nil {
 		return err
 	}
@@ -233,7 +241,7 @@ func Format(options *Options) error {
 
 // Dump command outputs hosts file contents as JSON
 func Dump(options *Options) error {
-	hostsfile, err := LoadHostfile()
+	hostsfile, err := LoadHostfile(options)
 	if err != nil {
 		return err
 	}
@@ -254,7 +262,7 @@ func Apply(options *Options, filename string) error {
 		return fmt.Errorf("Unable to read JSON from %s: %s", filename, err)
 	}
 
-	hostfile, err := LoadHostfile()
+	hostfile, err := LoadHostfile(options)
 	if err != nil {
 		return err
 	}

commands_test.go

@@ -1,6 +1,8 @@
 package main
 
 import (
+	"os"
+	"path/filepath"
 	"testing"
 )
 
@@ -24,3 +26,14 @@ func TestStrPadRight(t *testing.T) {
 		}
 	}
 }
+
+func TestLoadHostfile(t *testing.T) {
+	// Issue #39: This hosts file contains a duplicate. We should paper over it.
+	os.Setenv("HOSTESS_PATH", filepath.Join("testdata", "issue39"))
+	defer os.Unsetenv("HOSTESS_PATH")
+	options := &Options{}
+
+	if _, err := LoadHostfile(options); err != nil {
+		t.Fatal(err)
+	}
+}

hostess/hostfile_test.go

@@ -61,12 +61,22 @@ func TestFormatHostfile(t *testing.T) {
 	// 1. We want localhost entries at the top
 	// 2. The rest are sorted by IP as STRINGS, not numeric values, so 10
 	//    precedes 8
-	const expected = `127.0.0.1 localhost devsite
+	expected := `127.0.0.1 localhost devsite
 127.0.1.1 ip-10-37-12-18
 # 8.8.8.8 google.com
 10.37.12.18 devsite.com m.devsite.com
 `
 
+	if runtime.GOOS == "windows" {
+		expected = `127.0.0.1 localhost
+127.0.0.1 devsite
+127.0.1.1 ip-10-37-12-18
+# 8.8.8.8 google.com
+10.37.12.18 devsite.com
+10.37.12.18 m.devsite.com
+`
+	}
+
 	hostfile := hostess.NewHostfile()
 	hostfile.Path = "./hosts"
 	hostfile.Hosts.Add(hostess.MustHostname("localhost", "127.0.0.1", true))

hostess/hostlist.go

@@ -1,10 +1,13 @@
 package hostess
 
 import (
+	"bytes"
 	"encoding/json"
 	"errors"
 	"fmt"
 	"net"
+	"os"
+	"runtime"
 	"sort"
 	"strings"
 )
@@ -374,9 +377,9 @@ func (h *Hostlist) GetUniqueIPs() []net.IP {
 // 2. Commented items are sorted displayed
 // 3. 127.* appears at the top of the list (so boot resolvers don't break)
 // 4. When present, "localhost" will always appear first in the domain list
-func (h *Hostlist) Format() []byte {
+func (h *Hostlist) FormatLinux() []byte {
 	h.Sort()
-	out := []byte{}
+	out := bytes.Buffer{}
 
 	// We want to output one line of hostnames per IP, so first we get that
 	// list of IPs and iterate.
@@ -400,19 +403,49 @@ func (h *Hostlist) Format() []byte {
 		// Finally, if the bucket contains anything, concatenate it all
 		// together and append it to the output. Also add a newline.
 		if len(enabledIPs) > 0 {
-			concat := fmt.Sprintf("%s %s", IP.String(), strings.Join(enabledIPs, " "))
-			out = append(out, []byte(concat)...)
-			out = append(out, []byte("\n")...)
+			out.WriteString(fmt.Sprintf("%s %s\n", IP.String(), strings.Join(enabledIPs, " ")))
 		}
 
 		if len(disabledIPs) > 0 {
-			concat := fmt.Sprintf("# %s %s", IP.String(), strings.Join(disabledIPs, " "))
-			out = append(out, []byte(concat)...)
-			out = append(out, []byte("\n")...)
+			out.WriteString(fmt.Sprintf("# %s %s\n", IP.String(), strings.Join(disabledIPs, " ")))
 		}
 	}
 
-	return out
+	return out.Bytes()
+}
+
+func (h Hostlist) FormatWindows() []byte {
+	h.Sort()
+	out := bytes.Buffer{}
+
+	for _, hostname := range h {
+		out.WriteString(hostname.Format())
+		out.WriteString("\n")
+	}
+
+	return out.Bytes()
+}
+
+func (h *Hostlist) Format() []byte {
+	format := os.Getenv(EnvHostessFmt)
+	if format == "" {
+		format = runtime.GOOS
+	}
+
+	switch format {
+	case "windows":
+		return h.FormatWindows()
+	case "unix":
+		return h.FormatLinux()
+	default:
+		// Theoretically the Windows format might be more compatible but there
+		// are a lot of different operating systems, and they're almost all
+		// unix-based OSes, so we'll just assume the linux format is OK. For
+		// example, FreeBSD, MacOS, and Linux all use the same format and while
+		// I haven't checked OpenBSD or NetBSD, I am going to assume they are
+		// OK with this format. If not we can add a case above.
+		return h.FormatLinux()
+	}
 }
 
 // Dump exports all entries in the Hostlist as JSON

hostess/hostlist_test.go

@@ -3,7 +3,9 @@ package hostess_test
 import (
 	"bytes"
 	"fmt"
+	"io/ioutil"
 	"net"
+	"path/filepath"
 	"testing"
 
 	"github.com/cbednarski/hostess/hostess"
@@ -95,6 +97,50 @@ func TestContainsDomainIp(t *testing.T) {
 	}
 }
 
+func TestFormatLinux(t *testing.T) {
+	hostfile := hostess.NewHostfile()
+	hostfile.Path = filepath.Join("testdata", "hostfile3")
+	if err := hostfile.Read(); err != nil {
+		t.Fatal(err)
+	}
+	if errs := hostfile.Parse(); len(errs) != 0 {
+		t.Fatal(errs)
+	}
+
+	expected, err := ioutil.ReadFile(filepath.Join("testdata", "expected-linux"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	output := hostfile.Hosts.FormatLinux()
+
+	if !bytes.Equal(output, expected) {
+		t.Error(Diff(string(expected), string(output)))
+	}
+}
+
+func TestFormatWindows(t *testing.T) {
+	hostfile := hostess.NewHostfile()
+	hostfile.Path = filepath.Join("testdata", "hostfile3")
+	if err := hostfile.Read(); err != nil {
+		t.Fatal(err)
+	}
+	if errs := hostfile.Parse(); len(errs) != 0 {
+		t.Fatal(errs)
+	}
+
+	expected, err := ioutil.ReadFile(filepath.Join("testdata", "expected-windows"))
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	output := hostfile.Hosts.FormatWindows()
+
+	if !bytes.Equal(output, expected) {
+		t.Error(Diff(string(expected), string(output)))
+	}
+}
+
 func TestFormat(t *testing.T) {
 	hosts := hostess.NewHostlist()
 	hosts.Add(hostess.MustHostname(domain, ip, false))

hostess/testdata/expected-linux

@@ -0,0 +1,8 @@
+127.0.0.1 localhost
+127.0.1.1 robobrain
+# 192.168.0.1 pie.dev.example.com
+192.168.0.2 cookie.example.com
+192.168.1.1 pie.example.com strawberry.pie.example.com
+::1 localhost cake.example.com hostname.candy hostname.pie
+fe:23b3:890e:342e::ef chocolate.pie.example.com strawberry.pie.example.com
+# fe:23b3:890e:342e::ef chocolate.cake.example.com chocolate.cookie.example.com chocolate.ru.example.com chocolate.tr.example.com dev.strawberry.pie.example.com

hostess/testdata/expected-windows

@@ -0,0 +1,17 @@
+127.0.0.1 localhost
+127.0.1.1 robobrain
+# 192.168.0.1 pie.dev.example.com
+192.168.0.2 cookie.example.com
+192.168.1.1 pie.example.com
+192.168.1.1 strawberry.pie.example.com
+::1 localhost
+::1 cake.example.com
+::1 hostname.candy
+::1 hostname.pie
+# fe:23b3:890e:342e::ef chocolate.cake.example.com
+# fe:23b3:890e:342e::ef chocolate.cookie.example.com
+fe:23b3:890e:342e::ef chocolate.pie.example.com
+# fe:23b3:890e:342e::ef chocolate.ru.example.com
+# fe:23b3:890e:342e::ef chocolate.tr.example.com
+# fe:23b3:890e:342e::ef dev.strawberry.pie.example.com
+fe:23b3:890e:342e::ef strawberry.pie.example.com

hostess/testdata/hostfile3

@@ -0,0 +1,12 @@
+#192.168.0.1 pie.dev.example.com
+192.168.0.2 cookie.example.com
+::1 hostname.pie hostname.candy cake.example.com
+fe:23b3:890e:342e::ef strawberry.pie.example.com
+# fe:23b3:890e:342e::ef dev.strawberry.pie.example.com
+127.0.1.1 robobrain
+# fe:23b3:890e:342e::ef chocolate.cake.example.com chocolate.ru.example.com chocolate.tr.example.com chocolate.cookie.example.com
+fe:23b3:890e:342e::ef chocolate.pie.example.com
+::1 localhost
+127.0.0.1 localhost
+192.168.1.1 pie.example.com
+192.168.1.1 strawberry.pie.example.com

main.go

@@ -33,8 +33,6 @@ Commands
 Flags
 
     -n will preview changes but not rewrite your hosts file
-    -4 limit changes to IPv4 entries
-    -6 limit changes to IPv6 entries
 
 Configuration
 
@@ -61,35 +59,35 @@ func ExitWithError(err error) {
 	}
 }
 
+func Usage() {
+	fmt.Print(help, hostess.GetHostsPath())
+	os.Exit(0)
+}
+
 func CommandUsage(command string) error {
 	return fmt.Errorf("Usage: %s %s <hostname>", os.Args[0], command)
 }
 
 func wrappedMain(args []string) error {
 	cli := flag.NewFlagSet(args[0], flag.ExitOnError)
-	ipv4 := cli.Bool("4", false, "IPv4")
-	ipv6 := cli.Bool("6", false, "IPv6")
 	preview := cli.Bool("n", false, "preview")
-	cli.Usage = func() {
-		fmt.Printf(help, hostess.GetHostsPath())
+	cli.Usage = Usage
+
+	command := ""
+	if len(args) > 1 {
+		command = args[1]
+	} else {
+		Usage()
 	}
 
-	if err := cli.Parse(args[1:]); err != nil {
+	if err := cli.Parse(args[2:]); err != nil {
 		return err
 	}
 
 	options := &Options{
-		IPVersion: 0,
-		Preview:   *preview,
-	}
-	if *ipv4 {
-		options.IPVersion = options.IPVersion | IPv4
-	}
-	if *ipv6 {
-		options.IPVersion = options.IPVersion | IPv6
+		Preview: *preview,
 	}
 
-	command := cli.Arg(0)
 	switch command {
 
 	case "-v", "--version", "version":
@@ -104,46 +102,46 @@ func wrappedMain(args []string) error {
 		return Format(options)
 
 	case "add":
-		if len(cli.Args()) != 3 {
+		if len(cli.Args()) != 2 {
 			return fmt.Errorf("Usage: %s add <hostname> <ip>", cli.Name())
 		}
-		return Add(options, cli.Arg(1), cli.Arg(2))
+		return Add(options, cli.Arg(0), cli.Arg(1))
 
 	case "rm":
-		if cli.Arg(1) == "" {
+		if cli.Arg(0) == "" {
 			return CommandUsage(command)
 		}
-		return Remove(options, cli.Arg(1))
+		return Remove(options, cli.Arg(0))
 
 	case "on":
-		if cli.Arg(1) == "" {
+		if cli.Arg(0) == "" {
 			return CommandUsage(command)
 		}
-		return Enable(options, cli.Arg(1))
+		return Enable(options, cli.Arg(0))
 
 	case "off":
-		if cli.Arg(1) == "" {
+		if cli.Arg(0) == "" {
 			return CommandUsage(command)
 		}
-		return Disable(options, cli.Arg(1))
+		return Disable(options, cli.Arg(0))
 
 	case "ls":
 		return List(options)
 
 	case "has":
-		if cli.Arg(1) == "" {
+		if cli.Arg(0) == "" {
 			return CommandUsage(command)
 		}
-		return Has(options, cli.Arg(1))
+		return Has(options, cli.Arg(0))
 
 	case "dump":
 		return Dump(options)
 
 	case "apply":
-		if cli.Arg(1) == "" {
+		if cli.Arg(0) == "" {
 			return fmt.Errorf("Usage: %s apply <filename>", args[0])
 		}
-		return Apply(options, cli.Arg(1))
+		return Apply(options, cli.Arg(0))
 
 	default:
 		return ErrInvalidCommand

main_test.go

@@ -1,9 +1,12 @@
 package main
 
 import (
+	"bytes"
 	"io"
 	"io/ioutil"
 	"os"
+	"path/filepath"
+	"runtime"
 	"strings"
 	"testing"
 
@@ -13,10 +16,20 @@ import (
 // CopyHostsFile creates a temporary hosts file in the system temp directory,
 // sets the HOSTESS_PATH environment variable, and returns the file path and a
 // cleanup function
-func CopyHostsFile(t *testing.T) (string, func()) {
+func CopyHostsFile(t *testing.T, fixtureFiles ...string) (string, func()) {
 	t.Helper()
 
-	fixture, err := os.Open("testdata/ubuntu.hosts")
+	fixtureFile := filepath.Join("testdata", "ubuntu.hosts")
+
+	// This is an optional argument so we'll default to the ubuntu.hosts above
+	// and only accept arity 1 if the user passes in extra data
+	if len(fixtureFiles) > 1 {
+		t.Fatalf("%s supplied too many arguments to CopyHostsFile", t.Name())
+	} else if len(fixtureFiles) == 1 {
+		fixtureFile = fixtureFiles[0]
+	}
+
+	fixture, err := os.Open(fixtureFile)
 	if err != nil {
 		t.Fatal(err)
 	}
@@ -36,6 +49,7 @@ func CopyHostsFile(t *testing.T) (string, func()) {
 
 	cleanup := func() {
 		os.Remove(temp.Name())
+		os.Unsetenv(hostess.EnvHostessPath)
 	}
 
 	return temp.Name(), cleanup
@@ -65,6 +79,20 @@ ff02::1 ip6-allnodes
 ff02::2 ip6-allrouters
 `
 
+	if runtime.GOOS == "windows" {
+		expected = `127.0.0.1 localhost
+127.0.0.1 myapp.local
+127.0.1.1 ubuntu
+192.168.0.30 raspberrypi
+::1 ip6-localhost
+::1 ip6-loopback
+fe00:: ip6-localnet
+ff00:: ip6-mcastprefix
+ff02::1 ip6-allnodes
+ff02::2 ip6-allrouters
+`
+	}
+
 	if output != expected {
 		t.Errorf("--- Expected ---\n%s\n--- Found ---\n%s\n", expected, output)
 	}
@@ -102,6 +130,22 @@ ff02::1 ip6-allnodes
 ff02::2 ip6-allrouters
 `
 
+	if runtime.GOOS == "windows" {
+		expected = `127.0.0.1 localhost
+127.0.0.1 my.new.website
+127.0.1.1 ubuntu
+10.20.0.23 myapp.local
+192.168.0.30 raspberrypi
+192.168.0.82 mediaserver
+::1 ip6-localhost
+::1 ip6-loopback
+fe00:: ip6-localnet
+ff00:: ip6-mcastprefix
+ff02::1 ip6-allnodes
+ff02::2 ip6-allrouters
+`
+	}
+
 	if output != expected {
 		t.Errorf("--- Expected ---\n%s\n--- Found ---\n%s\n", expected, output)
 	}
@@ -133,6 +177,18 @@ ff02::1 ip6-allnodes
 ff02::2 ip6-allrouters
 `
 
+	if runtime.GOOS == "windows" {
+		expected = `127.0.0.1 localhost
+127.0.1.1 ubuntu
+::1 ip6-localhost
+::1 ip6-loopback
+fe00:: ip6-localnet
+ff00:: ip6-mcastprefix
+ff02::1 ip6-allnodes
+ff02::2 ip6-allrouters
+`
+	}
+
 	if output != expected {
 		t.Errorf("--- Expected ---\n%s\n--- Found ---\n%s\n", expected, output)
 	}
@@ -166,7 +222,81 @@ ff02::1 ip6-allnodes
 ff02::2 ip6-allrouters
 `
 
+	if runtime.GOOS == "windows" {
+		expected = `127.0.0.1 localhost
+# 127.0.0.1 myapp.local
+127.0.1.1 ubuntu
+# 192.168.0.30 raspberrypi
+::1 ip6-localhost
+::1 ip6-loopback
+fe00:: ip6-localnet
+ff00:: ip6-mcastprefix
+ff02::1 ip6-allnodes
+ff02::2 ip6-allrouters
+`
+	}
+
 	if output != expected {
 		t.Errorf("--- Expected ---\n%s\n--- Found ---\n%s\n", expected, output)
 	}
 }
+
+func TestExitCodeFmt(t *testing.T) {
+	temp, cleanup := CopyHostsFile(t, filepath.Join("testdata", "issue39"))
+	defer cleanup()
+
+	state1, err := ioutil.ReadFile(temp)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	t.Logf("%s", state1)
+
+	if err := wrappedMain([]string{"hostess", "fmt", "-n"}); err != ErrParsingHostsFile {
+		t.Fatalf(`Expected %q, found %v`, ErrParsingHostsFile, err)
+	}
+
+	state2, err := ioutil.ReadFile(temp)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if !bytes.Equal(state1, state2) {
+		t.Error("Expected hosts contents before and after fix -n to be the same")
+	}
+
+	if err := wrappedMain([]string{"hostess", "fmt"}); err != nil {
+		t.Fatalf("Unexpected error: %s", err)
+	}
+
+	finalExpected := `127.0.0.1 localhost kubernetes.docker.internal
+::1 localhost
+`
+	if runtime.GOOS == "windows" {
+		finalExpected = `127.0.0.1 localhost
+127.0.0.1 kubernetes.docker.internal
+::1 localhost
+`
+	}
+
+	state3, err := ioutil.ReadFile(temp)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	if string(state3) != finalExpected {
+		t.Fatalf("---- Expected ----\n%s\n---- Found ----\n%s\n", finalExpected, string(state3))
+	}
+}
+
+func TestNoCommand(t *testing.T) {
+	if err := wrappedMain([]string{"main"}); err != nil {
+		t.Fatal(err)
+	}
+}
+
+func TestNoArgs(t *testing.T) {
+	if err := wrappedMain([]string{"main", ""}); err != nil {
+		t.Fatal(err)
+	}
+}

testdata/issue39

@@ -0,0 +1,6 @@
+127.0.0.1 localhost kubernetes.docker.internal
+::1 localhost
+# Added by Docker Desktop
+# To allow the same kube context to work on the host and the container:
+127.0.0.1 kubernetes.docker.internal
+# End of section