Fix parse token expiration (#2650)

Fixes: #2649 .

Author: christoph-jerolimov

github/github.go

@@ -571,7 +571,8 @@ type Response struct {
 	// propagate to Response.
 	Rate Rate
 
-	// token's expiration date
+	// token's expiration date. Timestamp is 0001-01-01 when token doesn't expire.
+	// So it is valid for TokenExpiration.Equal(Timestamp{}) or TokenExpiration.Time.After(time.Now())
 	TokenExpiration Timestamp
 }
 
@@ -672,14 +673,19 @@ func parseRate(r *http.Response) Rate {
 }
 
 // parseTokenExpiration parses the TokenExpiration related headers.
+// Returns 0001-01-01 if the header is not defined or could not be parsed.
 func parseTokenExpiration(r *http.Response) Timestamp {
-	var exp Timestamp
 	if v := r.Header.Get(headerTokenExpiration); v != "" {
-		if t, err := time.Parse("2006-01-02 03:04:05 MST", v); err == nil {
-			exp = Timestamp{t.Local()}
+		if t, err := time.Parse("2006-01-02 15:04:05 MST", v); err == nil {
+			return Timestamp{t.Local()}
+		}
+		// Some tokens include the timezone offset instead of the timezone.
+		// https://github.com/google/go-github/issues/2649
+		if t, err := time.Parse("2006-01-02 15:04:05 -0700", v); err == nil {
+			return Timestamp{t.Local()}
 		}
 	}
-	return exp
+	return Timestamp{} // 0001-01-01 00:00:00
 }
 
 type requestContext uint8

github/github_test.go

@@ -2860,6 +2860,16 @@ func TestParseTokenExpiration(t *testing.T) {
 			header: "2021-09-03 02:34:04 UTC",
 			want:   Timestamp{time.Date(2021, time.September, 3, 2, 34, 4, 0, time.UTC)},
 		},
+		{
+			header: "2021-09-03 14:34:04 UTC",
+			want:   Timestamp{time.Date(2021, time.September, 3, 14, 34, 4, 0, time.UTC)},
+		},
+		// Some tokens include the timezone offset instead of the timezone.
+		// https://github.com/google/go-github/issues/2649
+		{
+			header: "2023-04-26 20:23:26 +0200",
+			want:   Timestamp{time.Date(2023, time.April, 26, 18, 23, 26, 0, time.UTC)},
+		},
 	}
 
 	for _, tt := range tests {
@@ -2871,7 +2881,7 @@ func TestParseTokenExpiration(t *testing.T) {
 		res.Header.Set(headerTokenExpiration, tt.header)
 		exp := parseTokenExpiration(res)
 		if !exp.Equal(tt.want) {
-			t.Errorf("parseTokenExpiration returned %#v, want %#v", exp, tt.want)
+			t.Errorf("parseTokenExpiration of %q\nreturned %#v\n    want %#v", tt.header, exp, tt.want)
 		}
 	}
 }