Add new Logger to iOS SDK to be able to intercept logs and report them to the appropriate system

Bug: webrtc:8695
Change-Id: I4f81529222dcaf3dded1a0ab93fabf5cda1fdef8
Reviewed-on: https://webrtc-review.googlesource.com/37001
Reviewed-by: Kári Helgason <kthelgason@webrtc.org>
Reviewed-by: Anders Carlsson <andersc@webrtc.org>
Commit-Queue: Kári Helgason <kthelgason@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#21821}

sdk/objc/Framework/UnitTests/RTCCallbackLogger_xctest.m

@@ -0,0 +1,103 @@
+/*
+ *  Copyright 2018 The WebRTC project authors. All Rights Reserved.
+ *
+ *  Use of this source code is governed by a BSD-style license
+ *  that can be found in the LICENSE file in the root of the source
+ *  tree. An additional intellectual property rights grant can be found
+ *  in the file PATENTS.  All contributing project authors may
+ *  be found in the AUTHORS file in the root of the source tree.
+ */
+
+#import "WebRTC/RTCCallbackLogger.h"
+
+#import <XCTest/XCTest.h>
+
+@interface RTCCallbackLoggerTests : XCTestCase
+
+@property(nonatomic, strong) RTCCallbackLogger *logger;
+
+@end
+
+@implementation RTCCallbackLoggerTests
+
+@synthesize logger;
+
+- (void)setUp {
+  self.logger = [[RTCCallbackLogger alloc] init];
+}
+
+- (void)tearDown {
+  self.logger = nil;
+}
+
+- (void)testCallbackGetsCalledForAppropriateLevel {
+  self.logger.severity = RTCLoggingSeverityWarning;
+
+  XCTestExpectation *callbackExpectation = [self expectationWithDescription:@"callbackWarning"];
+
+  [self.logger start:^(NSString *message) {
+    XCTAssertTrue([message hasSuffix:@"Horrible error\n"]);
+    [callbackExpectation fulfill];
+  }];
+
+  RTCLogError("Horrible error");
+
+  [self waitForExpectations:@[ callbackExpectation ] timeout:10.0];
+}
+
+- (void)testCallbackDoesNotGetCalledForOtherLevels {
+  self.logger.severity = RTCLoggingSeverityError;
+
+  XCTestExpectation *callbackExpectation = [self expectationWithDescription:@"callbackError"];
+
+  [self.logger start:^(NSString *message) {
+    XCTAssertTrue([message hasSuffix:@"Horrible error\n"]);
+    [callbackExpectation fulfill];
+  }];
+
+  RTCLogInfo("Just some info");
+  RTCLogWarning("Warning warning");
+  RTCLogError("Horrible error");
+
+  [self waitForExpectations:@[ callbackExpectation ] timeout:10.0];
+}
+
+- (void)testStartingWithNilCallbackDoesNotCrash {
+  [self.logger start:nil];
+
+  RTCLogError("Horrible error");
+}
+
+- (void)testStopCallbackLogger {
+  XCTestExpectation *callbackExpectation = [self expectationWithDescription:@"stopped"];
+
+  [self.logger start:^(NSString *message) {
+    [callbackExpectation fulfill];
+  }];
+
+  [self.logger stop];
+
+  RTCLogInfo("Just some info");
+
+  XCTWaiter *waiter = [[XCTWaiter alloc] init];
+  XCTWaiterResult result = [waiter waitForExpectations:@[ callbackExpectation ] timeout:1.0];
+  XCTAssertEqual(result, XCTWaiterResultTimedOut);
+}
+
+- (void)testDestroyingCallbackLogger {
+  XCTestExpectation *callbackExpectation = [self expectationWithDescription:@"destroyed"];
+
+  [self.logger start:^(NSString *message) {
+    [callbackExpectation fulfill];
+  }];
+
+  self.logger = nil;
+
+  RTCLogInfo("Just some info");
+
+  XCTWaiter *waiter = [[XCTWaiter alloc] init];
+  XCTWaiterResult result = [waiter waitForExpectations:@[ callbackExpectation ] timeout:1.0];
+  XCTAssertEqual(result, XCTWaiterResultTimedOut);
+}
+
+@end