internal: remove fallback parsing for expires_in

Facebook has correctted its OAuth2 implementation. The code as
a fallback can be removed now.

Updates #51, #239

Change-Id: Ib5f84bc35c0c4ecbdd25d4169f950410d4ae79a2
Reviewed-on: https://go-review.googlesource.com/c/oauth2/+/168017
Reviewed-by: Brad Fitzpatrick <bradfitz@golang.org>
Reviewed-by: JBD <jbd@google.com>
Run-TryBot: Brad Fitzpatrick <bradfitz@golang.org>
TryBot-Result: Gobot Gobot <gobot@golang.org>

Author: ggicci

facebook/facebook.go

@@ -11,6 +11,6 @@ import (
 
 // Endpoint is Facebook's OAuth 2.0 endpoint.
 var Endpoint = oauth2.Endpoint{
-	AuthURL:  "https://www.facebook.com/v3.1/dialog/oauth",
-	TokenURL: "https://graph.facebook.com/v3.1/oauth/access_token",
+	AuthURL:  "https://www.facebook.com/v3.2/dialog/oauth",
+	TokenURL: "https://graph.facebook.com/v3.2/oauth/access_token",
 }

internal/token.go

@@ -63,16 +63,12 @@ type tokenJSON struct {
 	TokenType    string         `json:"token_type"`
 	RefreshToken string         `json:"refresh_token"`
 	ExpiresIn    expirationTime `json:"expires_in"` // at least PayPal returns string, while most return number
-	Expires      expirationTime `json:"expires"`    // broken Facebook spelling of expires_in
 }
 
 func (e *tokenJSON) expiry() (t time.Time) {
 	if v := e.ExpiresIn; v != 0 {
 		return time.Now().Add(time.Duration(v) * time.Second)
 	}
-	if v := e.Expires; v != 0 {
-		return time.Now().Add(time.Duration(v) * time.Second)
-	}
 	return
 }
 
@@ -264,12 +260,6 @@ func doTokenRoundTrip(ctx context.Context, req *http.Request) (*Token, error) {
 			Raw:          vals,
 		}
 		e := vals.Get("expires_in")
-		if e == "" || e == "null" {
-			// TODO(jbd): Facebook's OAuth2 implementation is broken and
-			// returns expires_in field in expires. Remove the fallback to expires,
-			// when Facebook fixes their implementation.
-			e = vals.Get("expires")
-		}
 		expires, _ := strconv.Atoi(e)
 		if expires != 0 {
 			token.Expiry = time.Now().Add(time.Duration(expires) * time.Second)

oauth2_test.go

@@ -275,26 +275,26 @@ const day = 24 * time.Hour
 func TestExchangeRequest_JSONResponse_Expiry(t *testing.T) {
 	seconds := int32(day.Seconds())
 	for _, c := range []struct {
-		name    string
-		expires string
-		want    bool
+		name        string
+		expires     string
+		want        bool
+		nullExpires bool
 	}{
-		{"normal", fmt.Sprintf(`"expires_in": %d`, seconds), true},
-		{"paypal", fmt.Sprintf(`"expires_in": "%d"`, seconds), true},
-		{"facebook", fmt.Sprintf(`"expires": %d`, seconds), true},
-		{"issue_239", fmt.Sprintf(`"expires_in": null, "expires": %d`, seconds), true},
-
-		{"wrong_type", `"expires": false`, false},
-		{"wrong_type2", `"expires": {}`, false},
-		{"wrong_value", `"expires": "zzz"`, false},
+		{"normal", fmt.Sprintf(`"expires_in": %d`, seconds), true, false},
+		{"paypal", fmt.Sprintf(`"expires_in": "%d"`, seconds), true, false},
+		{"issue_239", fmt.Sprintf(`"expires_in": null`), true, true},
+
+		{"wrong_type", `"expires_in": false`, false, false},
+		{"wrong_type2", `"expires_in": {}`, false, false},
+		{"wrong_value", `"expires_in": "zzz"`, false, false},
 	} {
 		t.Run(c.name, func(t *testing.T) {
-			testExchangeRequest_JSONResponse_expiry(t, c.expires, c.want)
+			testExchangeRequest_JSONResponse_expiry(t, c.expires, c.want, c.nullExpires)
 		})
 	}
 }
 
-func testExchangeRequest_JSONResponse_expiry(t *testing.T, exp string, want bool) {
+func testExchangeRequest_JSONResponse_expiry(t *testing.T, exp string, want, nullExpires bool) {
 	ts := httptest.NewServer(http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
 		w.Header().Set("Content-Type", "application/json")
 		w.Write([]byte(fmt.Sprintf(`{"access_token": "90d", "scope": "user", "token_type": "bearer", %s}`, exp)))
@@ -303,7 +303,7 @@ func testExchangeRequest_JSONResponse_expiry(t *testing.T, exp string, want bool
 	conf := newConf(ts.URL)
 	t1 := time.Now().Add(day)
 	tok, err := conf.Exchange(context.Background(), "exchange-code")
-	t2 := time.Now().Add(day)
+	t2 := t1.Add(day)
 
 	if got := (err == nil); got != want {
 		if want {
@@ -319,8 +319,12 @@ func testExchangeRequest_JSONResponse_expiry(t *testing.T, exp string, want bool
 		t.Fatalf("Token invalid. Got: %#v", tok)
 	}
 	expiry := tok.Expiry
+
+	if nullExpires && expiry.IsZero() {
+		return
+	}
 	if expiry.Before(t1) || expiry.After(t2) {
-		t.Errorf("Unexpected value for Expiry: %v (shold be between %v and %v)", expiry, t1, t2)
+		t.Errorf("Unexpected value for Expiry: %v (should be between %v and %v)", expiry, t1, t2)
 	}
 }