adiciona função closer

interface_closer/closer.go

@@ -0,0 +1,13 @@
+package closer
+
+import (
+	"fmt"
+	"io"
+)
+
+func Closer(a io.Closer) {
+	err := a.Close()
+	if err != nil {
+		fmt.Println(err)
+	}
+}

interface_closer/closer_test.go

@@ -0,0 +1,95 @@
+package closer
+
+import (
+	"errors"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"os"
+	"testing"
+)
+
+type closerSuccess struct {
+}
+
+func (c closerSuccess) Close() (err error) {
+	return
+}
+
+type closerError struct {
+}
+
+func (c closerError) Close() (err error) {
+	err = errors.New("closer error")
+	return
+}
+
+func TestCloser(t *testing.T) {
+
+	getStdout := func(obj io.Closer) (out []byte, err error) {
+		rescueStdout := os.Stdout
+		defer func() { os.Stdout = rescueStdout }()
+		r, w, err := os.Pipe()
+		if err != nil {
+			return nil, err
+		}
+		os.Stdout = w
+
+		Closer(obj)
+
+		err = w.Close()
+		if err != nil {
+			return
+		}
+		out, err = ioutil.ReadAll(r)
+		return
+	}
+
+	cs := closerSuccess{}
+	ce := closerError{}
+
+	type args struct {
+		body io.Closer
+	}
+	type expected struct {
+		err bool
+	}
+	tests := []struct {
+		name string
+		args args
+		want expected
+	}{
+		{
+			name: "success",
+			args: args{
+				body: cs,
+			},
+			want: expected{
+				err: false,
+			},
+		},
+		{
+			name: "error",
+			args: args{
+				body: ce,
+			},
+			want: expected{
+				err: true,
+			},
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			out, err := getStdout(tt.args.body)
+			if err != nil {
+				t.Error(err)
+				return
+			}
+
+			if (len(out) > 0) != tt.want.err {
+				fmt.Printf("out: %q\n", string(out))
+				t.Errorf("closer() unexpected log %q", string(out))
+			}
+		})
+	}
+}

interface_closer/main/main.go

@@ -0,0 +1,31 @@
+package main
+
+import (
+	"fmt"
+	"io"
+	"os"
+)
+
+func closer(a io.Closer) {
+	err := a.Close()
+	if err != nil {
+		fmt.Println(err)
+	}
+}
+
+func main() {
+	file, err := os.Open("nome.txt")
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	defer closer(file)
+
+	file2, err := os.Open("nome.txt")
+	if err != nil {
+		fmt.Println(err)
+		return
+	}
+	defer closer(file2)
+	// ....
+}