tomll: port to v2 (#727)

Fixes #721

README.md

@@ -209,7 +209,7 @@ In case of trouble: [Go Modules FAQ][mod-faq].
 
 ## Tools
 
-Go-toml provides two handy command line tools:
+Go-toml provides three handy command line tools:
 
  * `tomljson`: Reads a TOML file and outputs its JSON representation.
 
@@ -225,6 +225,13 @@ Go-toml provides two handy command line tools:
     $ jsontoml --help
     ```
 
+ * `tomll`: Lints and reformats a TOML file.
+
+    ```
+    $ go install github.com/pelletier/go-toml/v2/cmd/tomll@latest
+    $ tomll --help
+    ```
+
 ## Migrating from v1
 
 This section describes the differences between v1 and v2, with some pointers on

cmd/jsontoml/main.go

@@ -13,15 +13,20 @@ import (
 	"github.com/pelletier/go-toml/v2/internal/cli"
 )
 
-func main() {
-	usage := `jsontoml can be used in two ways:
+const usage = `jsontoml can be used in two ways:
 Reading from stdin:
   cat file.json | jsontoml > file.toml
 
 Reading from a file:
   jsontoml file.json > file.toml
 `
-	cli.Execute(usage, convert)
+
+func main() {
+	p := cli.Program{
+		Usage: usage,
+		Fn:    convert,
+	}
+	p.Execute()
 }
 
 func convert(r io.Reader, w io.Writer) error {

cmd/tomljson/main.go

@@ -15,15 +15,20 @@ import (
 	"github.com/pelletier/go-toml/v2/internal/cli"
 )
 
-func main() {
-	usage := `tomljson can be used in two ways:
+const usage = `tomljson can be used in two ways:
 Reading from stdin:
   cat file.toml | tomljson > file.json
 
 Reading from a file:
   tomljson file.toml > file.json
 `
-	cli.Execute(usage, convert)
+
+func main() {
+	p := cli.Program{
+		Usage: usage,
+		Fn:    convert,
+	}
+	p.Execute()
 }
 
 func convert(r io.Reader, w io.Writer) error {

cmd/tomll/main.go

@@ -0,0 +1,46 @@
+// Tomll is a linter for TOML
+//
+// Usage:
+//   cat file.toml | tomll > file_linted.toml
+//   tomll file1.toml file2.toml # lint the two files in place
+package main
+
+import (
+	"io"
+
+	"github.com/pelletier/go-toml/v2"
+	"github.com/pelletier/go-toml/v2/internal/cli"
+)
+
+const usage = `tomll can be used in two ways:
+
+Reading from stdin, writing to stdout:
+  cat file.toml | tomll > file.toml
+
+Reading and updating a list of files in place:
+  tomll a.toml b.toml c.toml
+
+When given a list of files, tomll will modify all files in place without asking.
+`
+
+func main() {
+	p := cli.Program{
+		Usage:   usage,
+		Fn:      convert,
+		Inplace: true,
+	}
+	p.Execute()
+}
+
+func convert(r io.Reader, w io.Writer) error {
+	var v interface{}
+
+	d := toml.NewDecoder(r)
+	err := d.Decode(&v)
+	if err != nil {
+		return err
+	}
+
+	e := toml.NewEncoder(w)
+	return e.Encode(v)
+}

cmd/tomll/main_test.go

@@ -0,0 +1,46 @@
+package main
+
+import (
+	"bytes"
+	"strings"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestConvert(t *testing.T) {
+	examples := []struct {
+		name     string
+		input    string
+		expected string
+		errors   bool
+	}{
+		{
+			name: "valid toml",
+			input: `
+mytoml.a = 42.0
+`,
+			expected: `[mytoml]
+a = 42.0
+
+`,
+		},
+		{
+			name:   "invalid toml",
+			input:  `[what`,
+			errors: true,
+		},
+	}
+
+	for _, e := range examples {
+		b := new(bytes.Buffer)
+		err := convert(strings.NewReader(e.input), b)
+		if e.errors {
+			require.Error(t, err)
+		} else {
+			assert.NoError(t, err)
+			assert.Equal(t, e.expected, b.String())
+		}
+	}
+}

internal/cli/cli.go

@@ -1,22 +1,32 @@
 package cli
 
 import (
+	"bytes"
 	"flag"
 	"fmt"
 	"io"
+	"io/ioutil"
 	"os"
 )
 
 type ConvertFn func(r io.Reader, w io.Writer) error
 
-func Execute(usage string, fn ConvertFn) {
-	flag.Usage = func() { fmt.Fprintf(os.Stderr, usage) }
-	flag.Parse()
-	os.Exit(processMain(flag.Args(), os.Stdin, os.Stdout, os.Stderr, fn))
+type Program struct {
+	Usage string
+	Fn    ConvertFn
+	// Inplace allows the command to take more than one file as argument and
+	// perform convertion in place on each provided file.
+	Inplace bool
 }
 
-func processMain(files []string, input io.Reader, output, error io.Writer, f ConvertFn) int {
-	err := run(files, input, output, f)
+func (p *Program) Execute() {
+	flag.Usage = func() { fmt.Fprintf(os.Stderr, p.Usage) }
+	flag.Parse()
+	os.Exit(p.main(flag.Args(), os.Stdin, os.Stdout, os.Stderr))
+}
+
+func (p *Program) main(files []string, input io.Reader, output, error io.Writer) int {
+	err := p.run(files, input, output)
 	if err != nil {
 		fmt.Fprintln(error, err.Error())
 		return -1
@@ -24,8 +34,11 @@ func processMain(files []string, input io.Reader, output, error io.Writer, f Con
 	return 0
 }
 
-func run(files []string, input io.Reader, output io.Writer, convert ConvertFn) error {
+func (p *Program) run(files []string, input io.Reader, output io.Writer) error {
 	if len(files) > 0 {
+		if p.Inplace {
+			return p.runAllFilesInPlace(files)
+		}
 		f, err := os.Open(files[0])
 		if err != nil {
 			return err
@@ -33,5 +46,31 @@ func run(files []string, input io.Reader, output io.Writer, convert ConvertFn) e
 		defer f.Close()
 		input = f
 	}
-	return convert(input, output)
+	return p.Fn(input, output)
+}
+
+func (p *Program) runAllFilesInPlace(files []string) error {
+	for _, path := range files {
+		err := p.runFileInPlace(path)
+		if err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func (p *Program) runFileInPlace(path string) error {
+	in, err := ioutil.ReadFile(path)
+	if err != nil {
+		return err
+	}
+
+	out := new(bytes.Buffer)
+
+	err = p.Fn(bytes.NewReader(in), out)
+	if err != nil {
+		return err
+	}
+
+	return ioutil.WriteFile(path, out.Bytes(), 0600)
 }

internal/cli/cli_test.go

@@ -6,6 +6,7 @@ import (
 	"io"
 	"io/ioutil"
 	"os"
+	"path"
 	"strings"
 	"testing"
 
@@ -13,6 +14,11 @@ import (
 	"github.com/stretchr/testify/require"
 )
 
+func processMain(args []string, input io.Reader, stdout, stderr io.Writer, f ConvertFn) int {
+	p := Program{Fn: f}
+	return p.main(args, input, stdout, stderr)
+}
+
 func TestProcessMainStdin(t *testing.T) {
 	stdout := new(bytes.Buffer)
 	stderr := new(bytes.Buffer)
@@ -72,3 +78,79 @@ func TestProcessMainFileDoesNotExist(t *testing.T) {
 	assert.Empty(t, stdout.String())
 	assert.NotEmpty(t, stderr.String())
 }
+
+func TestProcessMainFilesInPlace(t *testing.T) {
+	dir, err := ioutil.TempDir("", "")
+	require.NoError(t, err)
+	defer os.RemoveAll(dir)
+
+	path1 := path.Join(dir, "file1")
+	path2 := path.Join(dir, "file2")
+
+	err = ioutil.WriteFile(path1, []byte("content 1"), 0600)
+	require.NoError(t, err)
+	err = ioutil.WriteFile(path2, []byte("content 2"), 0600)
+	require.NoError(t, err)
+
+	p := Program{
+		Fn:      dummyFileFn,
+		Inplace: true,
+	}
+
+	exit := p.main([]string{path1, path2}, os.Stdin, os.Stdout, os.Stderr)
+
+	require.Equal(t, 0, exit)
+
+	v1, err := ioutil.ReadFile(path1)
+	require.NoError(t, err)
+	require.Equal(t, "1", string(v1))
+
+	v2, err := ioutil.ReadFile(path2)
+	require.NoError(t, err)
+	require.Equal(t, "2", string(v2))
+}
+
+func TestProcessMainFilesInPlaceErrRead(t *testing.T) {
+	p := Program{
+		Fn:      dummyFileFn,
+		Inplace: true,
+	}
+
+	exit := p.main([]string{"/this/path/is/invalid"}, os.Stdin, os.Stdout, os.Stderr)
+
+	require.Equal(t, -1, exit)
+}
+
+func TestProcessMainFilesInPlaceFailFn(t *testing.T) {
+	dir, err := ioutil.TempDir("", "")
+	require.NoError(t, err)
+	defer os.RemoveAll(dir)
+
+	path1 := path.Join(dir, "file1")
+
+	err = ioutil.WriteFile(path1, []byte("content 1"), 0600)
+	require.NoError(t, err)
+
+	p := Program{
+		Fn:      func(io.Reader, io.Writer) error { return fmt.Errorf("oh no") },
+		Inplace: true,
+	}
+
+	exit := p.main([]string{path1}, os.Stdin, os.Stdout, os.Stderr)
+
+	require.Equal(t, -1, exit)
+
+	v1, err := ioutil.ReadFile(path1)
+	require.NoError(t, err)
+	require.Equal(t, "content 1", string(v1))
+}
+
+func dummyFileFn(r io.Reader, w io.Writer) error {
+	b, err := ioutil.ReadAll(r)
+	if err != nil {
+		return err
+	}
+	v := strings.SplitN(string(b), " ", 2)[1]
+	_, err = w.Write([]byte(v))
+	return err
+}