test json marshal and unmarshal

deviceauth.go

@@ -9,6 +9,7 @@ import (
 	"net/http"
 	"net/url"
 	"strings"
+	"time"
 
 	"golang.org/x/net/context/ctxhttp"
 )
@@ -20,17 +21,44 @@ const (
 	errExpiredToken         = "expired_token"
 )
 
-type DeviceAuth struct {
-	DeviceCode              string `json:"device_code"`
-	UserCode                string `json:"user_code"`
-	VerificationURI         string `json:"verification_uri,verification_url"`
-	VerificationURIComplete string `json:"verification_uri_complete,omitempty"`
-	ExpiresIn               int    `json:"expires_in"`
-	Interval                int    `json:"interval,omitempty"`
+type DeviceAuthResponse struct {
+	DeviceCode              string    `json:"device_code"`
+	UserCode                string    `json:"user_code"`
+	VerificationURI         string    `json:"verification_uri"`
+	VerificationURIComplete string    `json:"verification_uri_complete,omitempty"`
+	Expiry                  time.Time `json:"expires_in"`
+	Interval                int       `json:"interval,omitempty"`
 	raw                     map[string]interface{}
 }
 
-func retrieveDeviceAuth(ctx context.Context, c *Config, v url.Values) (*DeviceAuth, error) {
+func (d DeviceAuthResponse) MarshalJSON() ([]byte, error) {
+	type Alias DeviceAuthResponse
+	return json.Marshal(&struct {
+		ExpiresIn int64 `json:"expires_in"`
+		*Alias
+	}{
+		ExpiresIn: int64(time.Until(d.Expiry).Seconds()),
+		Alias:     (*Alias)(&d),
+	})
+
+}
+
+func (c *DeviceAuthResponse) UnmarshalJSON(data []byte) error {
+	type Alias DeviceAuthResponse
+	aux := &struct {
+		ExpiresIn int64 `json:"expires_in"`
+		*Alias
+	}{
+		Alias: (*Alias)(c),
+	}
+	if err := json.Unmarshal(data, &aux); err != nil {
+		return err
+	}
+	c.Expiry = time.Now().UTC().Add(time.Second * time.Duration(aux.ExpiresIn))
+	return nil
+}
+
+func retrieveDeviceAuth(ctx context.Context, c *Config, v url.Values) (*DeviceAuthResponse, error) {
 	req, err := http.NewRequest("POST", c.Endpoint.DeviceAuthURL, strings.NewReader(v.Encode()))
 	if err != nil {
 		return nil, err
@@ -54,7 +82,7 @@ func retrieveDeviceAuth(ctx context.Context, c *Config, v url.Values) (*DeviceAu
 		}
 	}
 
-	da := &DeviceAuth{}
+	da := &DeviceAuthResponse{}
 	err = json.Unmarshal(body, &da)
 	if err != nil {
 		return nil, fmt.Errorf("unmarshal %s", err)

deviceauth_test.go

@@ -0,0 +1,36 @@
+package oauth2
+
+import (
+	"encoding/json"
+	"testing"
+	"time"
+
+	"github.com/google/go-cmp/cmp"
+	"github.com/google/go-cmp/cmp/cmpopts"
+)
+
+func TestDeviceAuthResponseMarshalJson(t *testing.T) {
+	d := DeviceAuthResponse{Expiry: time.Now().Add(100 * time.Second)}
+	gotBytes, err := json.Marshal(d)
+	if err != nil {
+		t.Fatal(err)
+	}
+	got := string(gotBytes)
+	want := `{"expires_in":99,"device_code":"","user_code":"","verification_uri":""}`
+	if got != want {
+		t.Errorf("want=%s, got=%s", want, got)
+	}
+}
+
+func TestDeviceAuthResponseUnmarshalJson(t *testing.T) {
+	data := []byte(`{"expires_in":100}`)
+	want := DeviceAuthResponse{Expiry: time.Now().UTC().Add(100 * time.Second)}
+	got := DeviceAuthResponse{}
+	err := json.Unmarshal(data, &got)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !cmp.Equal(got, want, cmpopts.IgnoreUnexported(DeviceAuthResponse{}), cmpopts.EquateApproxTime(time.Second)) {
+		t.Errorf("want=%#v, got=%#v", want, got)
+	}
+}

oauth2.go

@@ -228,7 +228,7 @@ func (c *Config) Exchange(ctx context.Context, code string, opts ...AuthCodeOpti
 
 // AuthDevice returns a device auth struct which contains a device code
 // and authorization information provided for users to enter on another device.
-func (c *Config) AuthDevice(ctx context.Context, opts ...AuthCodeOption) (*DeviceAuth, error) {
+func (c *Config) AuthDevice(ctx context.Context, opts ...AuthCodeOption) (*DeviceAuthResponse, error) {
 	v := url.Values{
 		"client_id": {c.ClientID},
 	}
@@ -242,7 +242,7 @@ func (c *Config) AuthDevice(ctx context.Context, opts ...AuthCodeOption) (*Devic
 }
 
 // Poll does a polling to exchange an device code for a token.
-func (c *Config) Poll(ctx context.Context, da *DeviceAuth, opts ...AuthCodeOption) (*Token, error) {
+func (c *Config) Poll(ctx context.Context, da *DeviceAuthResponse, opts ...AuthCodeOption) (*Token, error) {
 	v := url.Values{
 		"client_id":   {c.ClientID},
 		"grant_type":  {"urn:ietf:params:oauth:grant-type:device_code"},