compare two file's md5 should be correct.

crmAttachment_test.go

 package main
 
-import "testing"
-
-import "encoding/json"
+import (
+	"encoding/json"
+	"os"
+	"testing"
+	"time"
+)
 
 func TestCRMAttachFile(t *testing.T) {
-
+	path1 := "media_for_test/200x200.png"
+	path2 := "/tmp/wechat_hitxy_测试_" + time.Now().Format("2006-Jan-02-05-04-05")
 	r, e := crmCreateAttachment("media_for_test/200x200.png")
 
 	AssertEqual(t, e, nil, "should be no error when create attachment")
 	AssertEqual(t, r.ID != "", true, "ID should not be empty ")
 	//
-	crmDownloadAttachmentAs(r.ID, "/tmp/wechat_hitxy_测试")
+	crmDownloadAttachmentAs(r.ID, path2)
+
+	AssertEqual(t, md5CompFile(path1, path2), true, "attachment should be downloade as same file ")
 
-	//TODO: two file should be equal
 	delete, e := crmDeleteEntity("Attachment", r.ID)
 	AssertEqual(t, delete, true, "temp attachment should have been deleted")
+
+	os.Remove(path2)
 }
 
 func TestDecodeJsonResponse(t *testing.T) {

fileinfo.go

 package main
 
 import (
+	"crypto/md5"
 	"fmt"
+	"io"
 	"io/ioutil"
 	"log"
 	"os"
 		os.MkdirAll(d, 0700)
 	}
 }
+
+func md5File(path string) (md5str string) {
+	f, err := os.Open(path)
+	if err != nil {
+		log.Println(err)
+		return
+	}
+	defer f.Close()
+
+	h := md5.New()
+	if _, err := io.Copy(h, f); err != nil {
+		log.Fatal(err)
+	}
+
+	return fmt.Sprintf("%x", h.Sum(nil))
+}
+
+func md5CompFile(path1, path2 string) (same bool) {
+	return md5File(path1) == md5File(path2)
+}