From daec4887492bf9d12366272353d2a9cfafeb9567 Mon Sep 17 00:00:00 2001
From: Philipp Hancke <philipp.hancke@googlemail.com>
Date: Tue, 15 Sep 2020 10:40:07 +0200
Subject: [PATCH] objc: fix rollback
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and add a unit test

BUG=webrtc:11796

Change-Id: I8e73b22f007c15c862faad7ca881d93c14a3a46f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/184160
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Commit-Queue: Philipp Hancke <philipp.hancke@googlemail.com>
Cr-Commit-Position: refs/heads/master@{#32104}
---
 .../peerconnection/RTCSessionDescription.mm   |  1 -
 .../RTCPeerConnectionFactory_xctest.m         | 51 +++++++++++++++++++
 2 files changed, 51 insertions(+), 1 deletion(-)

diff --git a/sdk/objc/api/peerconnection/RTCSessionDescription.mm b/sdk/objc/api/peerconnection/RTCSessionDescription.mm
index 15865dd1ec..9fd97fee23 100644
--- a/sdk/objc/api/peerconnection/RTCSessionDescription.mm
+++ b/sdk/objc/api/peerconnection/RTCSessionDescription.mm
@@ -31,7 +31,6 @@
 }
 
 - (instancetype)initWithType:(RTCSdpType)type sdp:(NSString *)sdp {
-  NSParameterAssert(sdp.length);
   if (self = [super init]) {
     _type = type;
     _sdp = [sdp copy];
diff --git a/sdk/objc/unittests/RTCPeerConnectionFactory_xctest.m b/sdk/objc/unittests/RTCPeerConnectionFactory_xctest.m
index 2737bb6eee..629095b81d 100644
--- a/sdk/objc/unittests/RTCPeerConnectionFactory_xctest.m
+++ b/sdk/objc/unittests/RTCPeerConnectionFactory_xctest.m
@@ -19,6 +19,7 @@
 #import "api/peerconnection/RTCRtpReceiver.h"
 #import "api/peerconnection/RTCRtpSender.h"
 #import "api/peerconnection/RTCRtpTransceiver.h"
+#import "api/peerconnection/RTCSessionDescription.h"
 #import "api/peerconnection/RTCVideoSource.h"
 
 #import <XCTest/XCTest.h>
@@ -270,6 +271,56 @@
   XCTAssertTrue(true, "Expect test does not crash");
 }
 
+- (void)testRollback {
+  @autoreleasepool {
+    RTC_OBJC_TYPE(RTCConfiguration) *config = [[RTC_OBJC_TYPE(RTCConfiguration) alloc] init];
+    config.sdpSemantics = RTCSdpSemanticsUnifiedPlan;
+    RTC_OBJC_TYPE(RTCMediaConstraints) *constraints =
+        [[RTC_OBJC_TYPE(RTCMediaConstraints) alloc] initWithMandatoryConstraints:@{
+          kRTCMediaConstraintsOfferToReceiveAudio : kRTCMediaConstraintsValueTrue
+        }
+                                                             optionalConstraints:nil];
+
+    __block RTC_OBJC_TYPE(RTCPeerConnectionFactory) * factory;
+    __block RTC_OBJC_TYPE(RTCPeerConnection) * pc1;
+    RTCSessionDescription *rollback = [[RTCSessionDescription alloc] initWithType:RTCSdpTypeRollback
+                                                                              sdp:@""];
+
+    @autoreleasepool {
+      factory = [[RTC_OBJC_TYPE(RTCPeerConnectionFactory) alloc] init];
+      pc1 = [factory peerConnectionWithConfiguration:config constraints:constraints delegate:nil];
+      dispatch_semaphore_t negotiatedSem = dispatch_semaphore_create(0);
+      [pc1 offerForConstraints:constraints
+             completionHandler:^(RTC_OBJC_TYPE(RTCSessionDescription) * offer, NSError * error) {
+               XCTAssertNil(error);
+               XCTAssertNotNil(offer);
+
+               __weak RTC_OBJC_TYPE(RTCPeerConnection) *weakPC1 = pc1;
+               [pc1 setLocalDescription:offer
+                      completionHandler:^(NSError *error) {
+                        XCTAssertNil(error);
+                        [weakPC1 setLocalDescription:rollback
+                                   completionHandler:^(NSError *error) {
+                                     XCTAssertNil(error);
+                                   }];
+                      }];
+               NSTimeInterval negotiationTimeout = 15;
+               dispatch_semaphore_wait(
+                   negotiatedSem,
+                   dispatch_time(DISPATCH_TIME_NOW, (int64_t)(negotiationTimeout * NSEC_PER_SEC)));
+
+               XCTAssertEqual(pc1.signalingState, RTCSignalingStateStable);
+
+               [pc1 close];
+               pc1 = nil;
+               factory = nil;
+             }];
+    }
+
+    XCTAssertTrue(true, "Expect test does not crash");
+  }
+}
+
 - (bool)negotiatePeerConnection:(RTC_OBJC_TYPE(RTCPeerConnection) *)pc1
              withPeerConnection:(RTC_OBJC_TYPE(RTCPeerConnection) *)pc2
              negotiationTimeout:(NSTimeInterval)timeout {