diff --git a/cmd/build_test.go b/cmd/build_test.go
index 6e86287..fc3841c 100644
--- a/cmd/build_test.go
+++ b/cmd/build_test.go
@@ -58,7 +58,7 @@ func TestGeneratedBinary(t *testing.T) {
 	assert.Equal(t, cnt > 0, true, "main.registerSelf function should be in the binary")
 
 	cnt = strings.Count(string(out), "GoCover")
-	assert.Equal(t, cnt > 0, true, "GoCover varibale should be in the binary")
+	assert.Equal(t, cnt > 0, true, "GoCover variable should be in the binary")
 }
 
 func TestBuildBinaryName(t *testing.T) {
@@ -86,7 +86,7 @@ func TestBuildBinaryName(t *testing.T) {
 	assert.Equal(t, cnt > 0, true, "main.registerSelf function should be in the binary")
 
 	cnt = strings.Count(string(out), "GoCover")
-	assert.Equal(t, cnt > 0, true, "GoCover varibale should be in the binary")
+	assert.Equal(t, cnt > 0, true, "GoCover variable should be in the binary")
 }
 
 // test if goc can get variables in internal package
@@ -115,5 +115,5 @@ func TestBuildBinaryForInternalPackage(t *testing.T) {
 	assert.Equal(t, cnt > 0, true, "GoCacheCover variable for internal package should be in the binary")
 
 	cnt = strings.Count(string(out), "internal.GoCover")
-	assert.Equal(t, cnt > 0, true, "internal.GoCover varibale should be in the binary")
+	assert.Equal(t, cnt > 0, true, "internal.GoCover variable should be in the binary")
 }
diff --git a/cmd/commonflags.go b/cmd/commonflags.go
index fcd63d4..9440276 100644
--- a/cmd/commonflags.go
+++ b/cmd/commonflags.go
@@ -70,7 +70,7 @@ func addRunFlags(cmdset *pflag.FlagSet) {
 	viper.BindPFlags(cmdset)
 }
 
-// add Cover Mode check
+// CoverMode represents the covermode when doing cover for source code
 type CoverMode struct {
 	mode string
 }
@@ -79,6 +79,7 @@ func (m *CoverMode) String() string {
 	return m.mode
 }
 
+// Set sets the value to the CoverMode struct, use 'count' as default if v is empty
 func (m *CoverMode) Set(v string) error {
 	if v == "" {
 		m.mode = "count"
@@ -91,11 +92,12 @@ func (m *CoverMode) Set(v string) error {
 	return nil
 }
 
+// Type returns the type of CoverMode
 func (m *CoverMode) Type() string {
 	return "string"
 }
 
-// add agentPort check
+// AgentPort is the struct to do agentPort check
 type AgentPort struct {
 	port string
 }
@@ -104,6 +106,7 @@ func (agent *AgentPort) String() string {
 	return agent.port
 }
 
+// Set sets the value to the AgentPort struct
 func (agent *AgentPort) Set(v string) error {
 	if v == "" {
 		agent.port = ""
@@ -117,6 +120,7 @@ func (agent *AgentPort) Set(v string) error {
 	return nil
 }
 
+// Type returns the type of AgentPort
 func (agent *AgentPort) Type() string {
 	return "string"
 }
diff --git a/cmd/install_test.go b/cmd/install_test.go
index d18a674..5b94c97 100644
--- a/cmd/install_test.go
+++ b/cmd/install_test.go
@@ -52,7 +52,7 @@ func TestInstalledBinaryForMod(t *testing.T) {
 	assert.Equal(t, cnt > 0, true, "main.registerSelf function should be in the binary")
 
 	cnt = strings.Count(string(out), "GoCover")
-	assert.Equal(t, cnt > 0, true, "GoCover varibale should be in the binary")
+	assert.Equal(t, cnt > 0, true, "GoCover variable should be in the binary")
 }
 
 func TestInstalledBinaryForLegacy(t *testing.T) {
@@ -80,5 +80,5 @@ func TestInstalledBinaryForLegacy(t *testing.T) {
 	assert.Equal(t, cnt > 0, true, "main.registerSelf function should be in the binary")
 
 	cnt = strings.Count(string(out), "GoCover")
-	assert.Equal(t, cnt > 0, true, "GoCover varibale should be in the binary")
+	assert.Equal(t, cnt > 0, true, "GoCover variable should be in the binary")
 }
diff --git a/pkg/build/build.go b/pkg/build/build.go
index 01ad30b..28ddb28 100644
--- a/pkg/build/build.go
+++ b/pkg/build/build.go
@@ -79,6 +79,7 @@ func NewBuild(buildflags string, args []string, workingDir string, outputDir str
 	return b, nil
 }
 
+// Build calls 'go build' tool to do building
 func (b *Build) Build() error {
 	log.Infoln("Go building in temp...")
 	// new -o will overwrite  previous ones
diff --git a/pkg/build/install.go b/pkg/build/install.go
index 8546e46..b5cb823 100644
--- a/pkg/build/install.go
+++ b/pkg/build/install.go
@@ -45,6 +45,7 @@ func NewInstall(buildflags string, args []string, workingDir string) (*Build, er
 	return b, nil
 }
 
+// Install use the 'go install' tool to install packages
 func (b *Build) Install() error {
 	log.Println("Go building in temp...")
 	cmd := exec.Command("/bin/bash", "-c", "go install "+b.BuildFlags+" "+b.Packages)
diff --git a/pkg/build/tmpfolder.go b/pkg/build/tmpfolder.go
index 5998ebd..bc40438 100644
--- a/pkg/build/tmpfolder.go
+++ b/pkg/build/tmpfolder.go
@@ -29,6 +29,7 @@ import (
 	"github.com/spf13/viper"
 )
 
+// MvProjectsToTmp moves the projects into a temporary directory
 func (b *Build) MvProjectsToTmp() error {
 	listArgs := []string{"-json"}
 	if len(b.BuildFlags) != 0 {
@@ -67,7 +68,7 @@ func (b *Build) MvProjectsToTmp() error {
 }
 
 func (b *Build) mvProjectsToTmp() error {
-	b.TmpDir = filepath.Join(os.TempDir(), TmpFolderName(b.WorkingDir))
+	b.TmpDir = filepath.Join(os.TempDir(), tmpFolderName(b.WorkingDir))
 
 	// Delete previous tmp folder and its content
 	os.RemoveAll(b.TmpDir)
@@ -110,7 +111,9 @@ func (b *Build) mvProjectsToTmp() error {
 	return nil
 }
 
-func TmpFolderName(path string) string {
+// tmpFolderName uses the first six characters of the input path's SHA256 checksum
+// as the suffix.
+func tmpFolderName(path string) string {
 	sum := sha256.Sum256([]byte(path))
 	h := fmt.Sprintf("%x", sum[:6])
 
diff --git a/pkg/cover/cover_test.go b/pkg/cover/cover_test.go
index f1a0de4..9c415ef 100644
--- a/pkg/cover/cover_test.go
+++ b/pkg/cover/cover_test.go
@@ -364,6 +364,9 @@ func TestCoverResultForInternalPackage(t *testing.T) {
 	}
 
 	out, err := ioutil.ReadFile(filepath.Join(testDir, "http_cover_apis_auto_generated.go"))
+	if err != nil {
+		assert.FailNow(t, "failed to read http_cover_apis_auto_generated.go file")
+	}
 	cnt := strings.Count(string(out), "GoCacheCover")
 	assert.Equal(t, cnt > 0, true, "GoCacheCover variable should be in http_cover_apis_auto_generated.go")
 
diff --git a/pkg/cover/server.go b/pkg/cover/server.go
index 05d0efe..0d09f52 100644
--- a/pkg/cover/server.go
+++ b/pkg/cover/server.go
@@ -116,7 +116,7 @@ func registerService(c *gin.Context) {
 
 	realIP := c.ClientIP()
 	if host != realIP {
-		log.Printf("the registed host %s of service %s is different with the real one %s, here we choose the real one", service.Name, host, realIP)
+		log.Printf("the registered host %s of service %s is different with the real one %s, here we choose the real one", service.Name, host, realIP)
 		service.Address = fmt.Sprintf("http://%s:%s", realIP, port)
 	}
 
diff --git a/pkg/github/github.go b/pkg/github/github.go
index bbefbf0..5ed7609 100644
--- a/pkg/github/github.go
+++ b/pkg/github/github.go
@@ -34,8 +34,11 @@ import (
 	"github.com/qiniu/goc/pkg/cover"
 )
 
+// CommentsPrefix is the prefix when commenting on Github Pull Requests
+// It is also the flag when checking whether the target comment exists or not to avoid duplicate
 const CommentsPrefix = "The following is the coverage report on the affected files."
 
+// PrComment is the entry which is able to comment on Github Pull Requests
 type PrComment struct {
 	RobotUserName string
 	RepoOwner     string
@@ -81,7 +84,7 @@ func NewPrClient(githubTokenPath, repoOwner, repoName, prNumStr, botUserName, co
 	}
 }
 
-//post github comment of diff coverage
+// CreateGithubComment post github comment of diff coverage
 func (c *PrComment) CreateGithubComment(commentPrefix string, diffCovList cover.DeltaCovList) (err error) {
 	if len(diffCovList) == 0 {
 		logrus.Printf("Detect 0 files coverage diff, will not comment to github.")
@@ -97,6 +100,7 @@ func (c *PrComment) CreateGithubComment(commentPrefix string, diffCovList cover.
 	return
 }
 
+// PostComment post comment on github. It erased the old one if existed to avoid duplicate
 func (c *PrComment) PostComment(content, commentPrefix string) error {
 	//step1: erase history similar comment to avoid too many comment for same job
 	err := c.EraseHistoryComment(commentPrefix)
@@ -116,7 +120,7 @@ func (c *PrComment) PostComment(content, commentPrefix string) error {
 	return nil
 }
 
-// erase history similar comment before post again
+// EraseHistoryComment erase history similar comment before post again
 func (c *PrComment) EraseHistoryComment(commentPrefix string) error {
 	comments, _, err := c.GithubClient.Issues.ListComments(c.Ctx, c.RepoOwner, c.RepoName, c.PrNumber, nil)
 	if err != nil {
@@ -161,7 +165,7 @@ func (c *PrComment) GetPrChangedFiles() (files []string, err error) {
 	return
 }
 
-//generate github comment content based on diff coverage and commentFlag
+// GenCommentContent generate github comment content based on diff coverage and commentFlag
 func GenCommentContent(commentPrefix string, delta cover.DeltaCovList) string {
 	var buf bytes.Buffer
 	table := tablewriter.NewWriter(&buf)
diff --git a/pkg/qiniu/mock.go b/pkg/qiniu/mock.go
index 59e56ad..d60c7bc 100644
--- a/pkg/qiniu/mock.go
+++ b/pkg/qiniu/mock.go
@@ -26,6 +26,7 @@ import (
 	"github.com/sirupsen/logrus"
 )
 
+// MockQiniuServer simulate qiniu cloud for testing
 func MockQiniuServer(config *Config) (client *Client, router *httprouter.Router, serverURL string, teardown func()) {
 	// router is the HTTP request multiplexer used with the test server.
 	router = httprouter.New()
@@ -54,7 +55,7 @@ func MockRouterAPI(router *httprouter.Router, profile string, count int) {
 		logrus.Infof("request url is: %s", r.URL.String())
 
 		if timeout > 0 {
-			timeout -= 1
+			timeout--
 			http.Error(w, "not found", http.StatusNotFound)
 			return
 		}
diff --git a/pkg/qiniu/object.go b/pkg/qiniu/object.go
index e374c60..3f10b37 100644
--- a/pkg/qiniu/object.go
+++ b/pkg/qiniu/object.go
@@ -38,6 +38,7 @@ type ObjectHandle struct {
 	client *client.Client
 }
 
+// Attrs get the object's metainfo
 func (o *ObjectHandle) Attrs(ctx context.Context) (storage.FileInfo, error) {
 	//TODO(CarlJi): need retry when errors
 	return o.bm.Stat(o.cfg.Bucket, o.key)