Test that unknown TLS 1.3 ticket extensions are tolerated.

Change-Id: Ifcdbeab9291d1141605a09a1960702c792cffa86
Reviewed-on: https://boringssl-review.googlesource.com/11561
Reviewed-by: Steven Valdez <svaldez@google.com>
Reviewed-by: David Benjamin <davidben@google.com>
Commit-Queue: David Benjamin <davidben@google.com>
CQ-Verified: CQ bot account: commit-bot@chromium.org <commit-bot@chromium.org>
diff --git a/ssl/test/runner/runner.go b/ssl/test/runner/runner.go
index a7fd154..95dbc0d 100644
--- a/ssl/test/runner/runner.go
+++ b/ssl/test/runner/runner.go
@@ -8595,6 +8595,17 @@
 		shouldFail:    true,
 		expectedError: ":PSK_IDENTITY_NOT_FOUND:",
 	})
+
+	// Test that unknown NewSessionTicket extensions are tolerated.
+	testCases = append(testCases, testCase{
+		name: "TLS13-CustomTicketExtension",
+		config: Config{
+			MaxVersion: VersionTLS13,
+			Bugs: ProtocolBugs{
+				CustomTicketExtension: "1234",
+			},
+		},
+	})
 }
 
 func addPeekTests() {