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clean up customizable stdout, stderr, and exit in parser config

This commit is contained in:
Alex Flint 2023-02-08 09:49:03 -05:00
parent 5dbdd5d0c5
commit df28e7154b
5 changed files with 80 additions and 133 deletions
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31
example_test.go
View File

@ -162,8 +162,7 @@ func Example_helpText() {
}
// This is only necessary when running inside golang's runnable example harness
osExit = func(int) {}
stdout = os.Stdout
mustParseExit = func(int) {}
MustParse(&args)
@ -195,8 +194,7 @@ func Example_helpPlaceholder() {
}
// This is only necessary when running inside golang's runnable example harness
osExit = func(int) {}
stdout = os.Stdout
mustParseExit = func(int) {}
MustParse(&args)
@ -236,8 +234,7 @@ func Example_helpTextWithSubcommand() {
}
// This is only necessary when running inside golang's runnable example harness
osExit = func(int) {}
stdout = os.Stdout
mustParseExit = func(int) {}
MustParse(&args)
@ -274,8 +271,7 @@ func Example_helpTextWhenUsingSubcommand() {
}
// This is only necessary when running inside golang's runnable example harness
osExit = func(int) {}
stdout = os.Stdout
mustParseExit = func(int) {}
MustParse(&args)
@ -311,10 +307,9 @@ func Example_writeHelpForSubcommand() {
}
// This is only necessary when running inside golang's runnable example harness
osExit = func(int) {}
stdout = os.Stdout
exit := func(int) {}
p, err := NewParser(Config{}, &args)
p, err := NewParser(Config{Exit: exit}, &args)
if err != nil {
fmt.Println(err)
os.Exit(1)
@ -360,10 +355,9 @@ func Example_writeHelpForSubcommandNested() {
}
// This is only necessary when running inside golang's runnable example harness
osExit = func(int) {}
stdout = os.Stdout
exit := func(int) {}
p, err := NewParser(Config{}, &args)
p, err := NewParser(Config{Exit: exit}, &args)
if err != nil {
fmt.Println(err)
os.Exit(1)
@ -397,8 +391,7 @@ func Example_errorText() {
}
// This is only necessary when running inside golang's runnable example harness
osExit = func(int) {}
stderr = os.Stdout
mustParseExit = func(int) {}
MustParse(&args)
@ -421,8 +414,7 @@ func Example_errorTextForSubcommand() {
}
// This is only necessary when running inside golang's runnable example harness
osExit = func(int) {}
stderr = os.Stdout
mustParseExit = func(int) {}
MustParse(&args)
@ -457,8 +449,7 @@ func Example_subcommand() {
}
// This is only necessary when running inside golang's runnable example harness
osExit = func(int) {}
stderr = os.Stdout
mustParseExit = func(int) {}
MustParse(&args)

65
parse.go
View File

@ -75,13 +75,28 @@ var ErrHelp = errors.New("help requested by user")
// ErrVersion indicates that --version was provided
var ErrVersion = errors.New("version requested by user")
// for monkey patching in example code
var mustParseExit = os.Exit
// MustParse processes command line arguments and exits upon failure
func MustParse(dest ...interface{}) *Parser {
p, err := NewParser(Config{}, dest...)
return mustParse(Config{Exit: mustParseExit}, dest...)
}
// mustParse is a helper that facilitates testing
func mustParse(config Config, dest ...interface{}) *Parser {
if config.Exit == nil {
config.Exit = os.Exit
}
if config.Out == nil {
config.Out = os.Stdout
}
p, err := NewParser(config, dest...)
if err != nil {
fmt.Fprintln(stdout, err)
osExit(-1)
return nil // just in case osExit was monkey-patched
fmt.Fprintln(config.Out, err)
config.Exit(-1)
return nil
}
p.MustParse(flags())
@ -121,9 +136,11 @@ type Config struct {
// subcommand
StrictSubcommands bool
OsExit func(int)
Stdout io.Writer
Stderr io.Writer
// Exit is called to terminate the process with an error code (defaults to os.Exit)
Exit func(int)
// Out is where help text, usage text, and failure messages are printed (defaults to os.Stdout)
Out io.Writer
}
// Parser represents a set of command line options with destination values
@ -137,10 +154,6 @@ type Parser struct {
// the following field changes during processing of command line arguments
lastCmd *command
osExit func(int)
stdout io.Writer
stderr io.Writer
}
// Versioned is the interface that the destination struct should implement to
@ -190,6 +203,14 @@ func walkFieldsImpl(t reflect.Type, visit func(field reflect.StructField, owner
// NewParser constructs a parser from a list of destination structs
func NewParser(config Config, dests ...interface{}) (*Parser, error) {
// fill in defaults
if config.Exit == nil {
config.Exit = os.Exit
}
if config.Out == nil {
config.Out = os.Stdout
}
// first pick a name for the command for use in the usage text
var name string
switch {
@ -205,20 +226,6 @@ func NewParser(config Config, dests ...interface{}) (*Parser, error) {
p := Parser{
cmd: &command{name: name},
config: config,
osExit: osExit,
stdout: stdout,
stderr: stderr,
}
if config.OsExit != nil {
p.osExit = config.OsExit
}
if config.Stdout != nil {
p.stdout = config.Stdout
}
if config.Stderr != nil {
p.stderr = config.Stderr
}
// make a list of roots
@ -506,11 +513,11 @@ func (p *Parser) MustParse(args []string) {
err := p.Parse(args)
switch {
case err == ErrHelp:
p.writeHelpForSubcommand(p.stdout, p.lastCmd)
p.osExit(0)
p.writeHelpForSubcommand(p.config.Out, p.lastCmd)
p.config.Exit(0)
case err == ErrVersion:
fmt.Fprintln(p.stdout, p.version)
p.osExit(0)
fmt.Fprintln(p.config.Out, p.version)
p.config.Exit(0)
case err != nil:
p.failWithSubcommand(err.Error(), p.lastCmd)
}

69
parse_test.go
View File

@ -885,26 +885,18 @@ func TestParserMustParse(t *testing.T) {
for _, tt := range tests {
tt := tt
t.Run(tt.name, func(t *testing.T) {
originalExit := osExit
originalStdout := stdout
defer func() {
osExit = originalExit
stdout = originalStdout
}()
var exitCode int
var stdout bytes.Buffer
exit := func(code int) { exitCode = code }
var exitCode *int
osExit = func(code int) { exitCode = &code }
var b bytes.Buffer
stdout = &b
p, err := NewParser(Config{}, &tt.args)
p, err := NewParser(Config{Exit: exit, Out: &stdout}, &tt.args)
require.NoError(t, err)
assert.NotNil(t, p)
p.MustParse(tt.cmdLine)
assert.NotNil(t, exitCode)
assert.Equal(t, tt.code, *exitCode)
assert.Contains(t, b.String(), tt.output)
assert.Equal(t, tt.code, exitCode)
assert.Contains(t, stdout.String(), tt.output)
})
}
}
@ -1484,70 +1476,53 @@ func TestUnexportedFieldsSkipped(t *testing.T) {
}
func TestMustParseInvalidParser(t *testing.T) {
originalExit := osExit
originalStdout := stdout
defer func() {
osExit = originalExit
stdout = originalStdout
}()
var exitCode int
osExit = func(code int) { exitCode = code }
stdout = &bytes.Buffer{}
var stdout bytes.Buffer
exit := func(code int) { exitCode = code }
var args struct {
CannotParse struct{}
}
parser := MustParse(&args)
parser := mustParse(Config{Out: &stdout, Exit: exit}, &args)
assert.Nil(t, parser)
assert.Equal(t, -1, exitCode)
}
func TestMustParsePrintsHelp(t *testing.T) {
originalExit := osExit
originalStdout := stdout
originalArgs := os.Args
defer func() {
osExit = originalExit
stdout = originalStdout
os.Args = originalArgs
}()
var exitCode *int
osExit = func(code int) { exitCode = &code }
os.Args = []string{"someprogram", "--help"}
stdout = &bytes.Buffer{}
var exitCode int
var stdout bytes.Buffer
exit := func(code int) { exitCode = code }
var args struct{}
parser := MustParse(&args)
parser := mustParse(Config{Out: &stdout, Exit: exit}, &args)
assert.NotNil(t, parser)
require.NotNil(t, exitCode)
assert.Equal(t, 0, *exitCode)
assert.Equal(t, 0, exitCode)
}
func TestMustParsePrintsVersion(t *testing.T) {
originalExit := osExit
originalStdout := stdout
originalArgs := os.Args
defer func() {
osExit = originalExit
stdout = originalStdout
os.Args = originalArgs
}()
var exitCode *int
osExit = func(code int) { exitCode = &code }
var exitCode int
var stdout bytes.Buffer
exit := func(code int) { exitCode = code }
os.Args = []string{"someprogram", "--version"}
var b bytes.Buffer
stdout = &b
var args versioned
parser := MustParse(&args)
parser := mustParse(Config{Out: &stdout, Exit: exit}, &args)
require.NotNil(t, parser)
require.NotNil(t, exitCode)
assert.Equal(t, 0, *exitCode)
assert.Equal(t, "example 3.2.1\n", b.String())
assert.Equal(t, 0, exitCode)
assert.Equal(t, "example 3.2.1\n", stdout.String())
}
type mapWithUnmarshalText struct {

14
usage.go
View File

@ -3,20 +3,12 @@ package arg
import (
"fmt"
"io"
"os"
"strings"
)
// the width of the left column
const colWidth = 25
// to allow monkey patching in tests
var (
stdout io.Writer = os.Stdout
stderr io.Writer = os.Stderr
osExit = os.Exit
)
// Fail prints usage information to stderr and exits with non-zero status
func (p *Parser) Fail(msg string) {
p.failWithSubcommand(msg, p.cmd)
@ -39,9 +31,9 @@ func (p *Parser) FailSubcommand(msg string, subcommand ...string) error {
// failWithSubcommand prints usage information for the given subcommand to stderr and exits with non-zero status
func (p *Parser) failWithSubcommand(msg string, cmd *command) {
p.writeUsageForSubcommand(p.stderr, cmd)
fmt.Fprintln(p.stderr, "error:", msg)
p.osExit(-1)
p.writeUsageForSubcommand(p.config.Out, cmd)
fmt.Fprintln(p.config.Out, "error:", msg)
p.config.Exit(-1)
}
// WriteUsage writes usage information to the given writer

34
usage_test.go
View File

@ -572,18 +572,9 @@ Options:
}
func TestFail(t *testing.T) {
originalStderr := stderr
originalExit := osExit
defer func() {
stderr = originalStderr
osExit = originalExit
}()
var b bytes.Buffer
stderr = &b
var stdout bytes.Buffer
var exitCode int
osExit = func(code int) { exitCode = code }
exit := func(code int) { exitCode = code }
expectedStdout := `
Usage: example [--foo FOO]
@ -593,27 +584,18 @@ error: something went wrong
var args struct {
Foo int
}
p, err := NewParser(Config{Program: "example"}, &args)
p, err := NewParser(Config{Program: "example", Exit: exit, Out: &stdout}, &args)
require.NoError(t, err)
p.Fail("something went wrong")
assert.Equal(t, expectedStdout[1:], b.String())
assert.Equal(t, expectedStdout[1:], stdout.String())
assert.Equal(t, -1, exitCode)
}
func TestFailSubcommand(t *testing.T) {
originalStderr := stderr
originalExit := osExit
defer func() {
stderr = originalStderr
osExit = originalExit
}()
var b bytes.Buffer
stderr = &b
var stdout bytes.Buffer
var exitCode int
osExit = func(code int) { exitCode = code }
exit := func(code int) { exitCode = code }
expectedStdout := `
Usage: example sub
@ -623,13 +605,13 @@ error: something went wrong
var args struct {
Sub *struct{} `arg:"subcommand"`
}
p, err := NewParser(Config{Program: "example"}, &args)
p, err := NewParser(Config{Program: "example", Exit: exit, Out: &stdout}, &args)
require.NoError(t, err)
err = p.FailSubcommand("something went wrong", "sub")
require.NoError(t, err)
assert.Equal(t, expectedStdout[1:], b.String())
assert.Equal(t, expectedStdout[1:], stdout.String())
assert.Equal(t, -1, exitCode)
}