Avoid extra buffer in commands

No need to use `bytes.Buffer` since we moved to
`buffio` package.

cmd/bundle.go

@@ -2,7 +2,6 @@ package cmd
 
 import (
 	"bufio"
-	"bytes"
 	"fmt"
 	"log"
 	"os"
@@ -23,11 +22,7 @@ var bundleCmd = &cobra.Command{
 	Run: func(cmd *cobra.Command, args []string) {
 		changelog := parser.Parse(inputFile)
 		bundleFiles(directory, changelog)
-
-		var buf bytes.Buffer
-		changelog.Render(&buf)
-
-		outputFile.ReadFrom(&buf)
+		changelog.Render(outputFile)
 	},
 }
 

cmd/commands.go

@@ -1,7 +1,6 @@
 package cmd
 
 import (
-	"bytes"
 	"fmt"
 	"strings"
 
@@ -24,11 +23,7 @@ func buildCommands(rootCmd *cobra.Command) {
 			Run: func(cmd *cobra.Command, args []string) {
 				changelog := parser.Parse(inputFile)
 				changelog.AddItem(cmdType, strings.Join(args, " "))
-
-				var buf bytes.Buffer
-				changelog.Render(&buf)
-
-				outputFile.ReadFrom(&buf)
+				changelog.Render(outputFile)
 			},
 		}
 

cmd/fmt.go

@@ -1,8 +1,6 @@
 package cmd
 
 import (
-	"bytes"
-
 	"github.com/rcmachado/changelog/parser"
 	"github.com/spf13/cobra"
 )
@@ -13,11 +11,7 @@ var fmtCmd = &cobra.Command{
 	Long:  "Reformats changelog input following keepachangelog.com spec",
 	Run: func(cmd *cobra.Command, args []string) {
 		changelog := parser.Parse(inputFile)
-
-		var buf bytes.Buffer
-		changelog.Render(&buf)
-
-		outputFile.ReadFrom(&buf)
+		changelog.Render(outputFile)
 	},
 }
 

cmd/release.go

@@ -1,7 +1,6 @@
 package cmd
 
 import (
-	"bytes"
 	"fmt"
 	"io"
 	"os"
@@ -25,9 +24,7 @@ It will normalize the output with the new version.
 `,
 	Args: cobra.ExactArgs(1),
 	Run: func(cmd *cobra.Command, args []string) {
-		var buf bytes.Buffer
-		release(inputFile, args, &buf)
-		outputFile.ReadFrom(&buf)
+		release(inputFile, args, outputFile)
 	},
 }
 

cmd/show.go

@@ -1,7 +1,6 @@
 package cmd
 
 import (
-	"bytes"
 	"fmt"
 	"os"
 
@@ -23,10 +22,7 @@ var showCmd = &cobra.Command{
 			os.Exit(3)
 		}
 
-		var buf bytes.Buffer
-		v.RenderChanges(&buf)
-
-		outputFile.ReadFrom(&buf)
+		v.RenderChanges(outputFile)
 	},
 }