Update to support prehooks and posthooks

client.go

@@ -15,8 +15,10 @@ const (
 
 // Client defines a HTTP client
 type Client struct {
-	Client  *http.Client
-	Retryer retry.Retryer
+	Client    *http.Client
+	Retryer   retry.Retryer
+	Prehooks  []Prehook
+	Posthooks []Posthook
 }
 
 // NewClient initialises a new `Client`
@@ -28,6 +30,8 @@ func NewClient(opts ...Option) *Client {
 		Retryer: retry.Retryer{
 			Attempts: defaultRetryAttempts,
 		},
+		Prehooks:  []Prehook{},
+		Posthooks: []Posthook{},
 	}
 
 	for _, opt := range opts {
@@ -41,20 +45,28 @@ func NewClient(opts ...Option) *Client {
 func (client *Client) Do(request *http.Request) (*http.Response, error) {
 	var (
 		response *http.Response
-	)
 
-	success, errs := client.Retryer.Do(func() error {
-		var err error
+		success, errs = client.Retryer.Do(func() error {
+			var err error
+
+			for _, prehook := range client.Prehooks {
+				prehook(request)
+			}
 
-		response, err = client.Client.Do(request)
+			response, err = client.Client.Do(request)
 
-		// Retry only on 5xx status codes
-		if response != nil && response.StatusCode >= http.StatusInternalServerError {
-			return fmt.Errorf("retrying on %s", response.Status)
-		}
+			for _, posthook := range client.Posthooks {
+				posthook(response, err)
+			}
 
-		return err
-	})
+			// Retry only on 5xx status codes
+			if response != nil && response.StatusCode >= http.StatusInternalServerError {
+				return fmt.Errorf("retrying on %s", response.Status)
+			}
+
+			return err
+		})
+	)
 
 	if !success {
 		return response, fmt.Errorf("httpclient: request occurred with errors: %s", errs)

client_test.go

@@ -88,3 +88,26 @@ func TestClient_DoWithInternalServerError(t *testing.T) {
 	assert.EqualError(t, err, "httpclient: request occurred with errors: retrying on 500 Internal Server Error; retrying on 500 Internal Server Error")
 	assert.Equal(t, http.StatusInternalServerError, response.StatusCode)
 }
+
+func TestClient_DoWithHook(t *testing.T) {
+	var (
+		url = httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+			w.WriteHeader(http.StatusOK)
+		})).URL
+		client = httpclient.NewClient(
+			httpclient.OptionAttempts(2),
+			httpclient.OptionAddPrehook(func(req *http.Request) {
+				assert.Equal(t, url, req.URL.String())
+			}),
+			httpclient.OptionAddPosthook(func(resp *http.Response, err error) {
+				assert.NoError(t, err)
+				assert.Equal(t, http.StatusOK, resp.StatusCode)
+			}),
+		)
+		request, _    = http.NewRequest(http.MethodPost, url, strings.NewReader(`{"foo": "bar"}`))
+		response, err = client.Do(request)
+	)
+
+	assert.NoError(t, err)
+	assert.Equal(t, http.StatusOK, response.StatusCode)
+}

go.sum

@@ -4,6 +4,7 @@ github.com/davecgh/go-spew v1.1.0 h1:ZDRjVQ15GmhC3fiQ8ni8+OwkZQO4DARzQgrnXU1Liz8
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
+github.com/stretchr/objx v0.1.0 h1:4G4v2dO3VZwixGIRoQ5Lfboy6nUhCyYzaqnIAPPhYs4=
 github.com/stretchr/objx v0.1.0/go.mod h1:HFkY916IF+rwdDfMAkV7OtwuqBVzrE8GR6GFx+wExME=
 github.com/stretchr/testify v1.5.1 h1:nOGnQDM7FYENwehXlg/kFVnos3rEvtKTjRvOWSzb6H4=
 github.com/stretchr/testify v1.5.1/go.mod h1:5W2xD1RspED5o8YsWQXVCued0rvSQ+mT+I5cxcmMvtA=

option.go

@@ -49,3 +49,17 @@ func OptionJitter(fn func(backoff time.Duration) time.Duration) Option {
 		client.Retryer.Jitter = fn
 	}
 }
+
+// OptionAddPrehook adds a prehook to `Client`
+func OptionAddPrehook(prehook func(request *http.Request)) Option {
+	return func(client *Client) {
+		client.Prehooks = append(client.Prehooks, prehook)
+	}
+}
+
+// OptionAddPosthook adds a posthook to `Client`
+func OptionAddPosthook(posthook func(response *http.Response, err error)) Option {
+	return func(client *Client) {
+		client.Posthooks = append(client.Posthooks, posthook)
+	}
+}

posthook.go

@@ -0,0 +1,6 @@
+package httpclient
+
+import "net/http"
+
+// Posthook defines a hook called after a HTTP request
+type Posthook func(response *http.Response, err error)

prehook.go

@@ -0,0 +1,6 @@
+package httpclient
+
+import "net/http"
+
+// Prehook defines a hook called before a HTTP request
+type Prehook func(request *http.Request)