Add -use-number flag to jsontoml util

cmd/jsontoml/main.go

@@ -19,6 +19,7 @@ package main
 
 import (
 	"encoding/json"
+	"flag"
 	"io"
 
 	"github.com/pelletier/go-toml/v2"
@@ -33,6 +34,10 @@ Reading from a file:
   jsontoml file.json > file.toml
 `
 
+var (
+	useNumber = flag.Bool("use-number", false, "Tells the json decoder to unmarshal numbers into json.Number type instead of float64")
+)
+
 func main() {
 	p := cli.Program{
 		Usage: usage,
@@ -45,11 +50,17 @@ func convert(r io.Reader, w io.Writer) error {
 	var v interface{}
 
 	d := json.NewDecoder(r)
+	e := toml.NewEncoder(w)
+
+	if useNumber != nil && *useNumber {
+		d.UseNumber()
+		e.SetJsonNumber(true)
+	}
+
 	err := d.Decode(&v)
 	if err != nil {
 		return err
 	}
 
-	e := toml.NewEncoder(w)
 	return e.Encode(v)
 }

cmd/jsontoml/main_test.go

@@ -11,10 +11,11 @@ import (
 
 func TestConvert(t *testing.T) {
 	examples := []struct {
-		name     string
-		input    string
-		expected string
-		errors   bool
+		name      string
+		input     string
+		expected  string
+		errors    bool
+		useNumber bool
 	}{
 		{
 			name: "valid json",
@@ -26,6 +27,19 @@ func TestConvert(t *testing.T) {
 }`,
 			expected: `[mytoml]
 a = 42.0
+`,
+		},
+		{
+			name:      "use json number",
+			useNumber: true,
+			input: `
+{
+  "mytoml": {
+    "a": 42
+  }
+}`,
+			expected: `[mytoml]
+a = 42
 `,
 		},
 		{
@@ -35,8 +49,13 @@ a = 42.0
 		},
 	}
 
+	trueValue := true
+
 	for _, e := range examples {
 		b := new(bytes.Buffer)
+		if e.useNumber {
+			useNumber = &trueValue
+		}
 		err := convert(strings.NewReader(e.input), b)
 		if e.errors {
 			require.Error(t, err)