Add -[RACSignal mergeWith:]

ReactiveCocoaFramework/ReactiveCocoa/RACSignal+Operations.h

@@ -194,6 +194,9 @@ extern const NSInteger RACSignalErrorNoMatchingCase;
 /// `reduceBlock`.
 + (RACSignal *)combineLatest:(id<NSFastEnumeration>)signals reduce:(id (^)())reduceBlock;
 
+/// Returns a signal that merges the receiver and the given signal with `+merge:`.
+- (RACSignal *)mergeWith:(RACSignal *)signal;
+
 /// Sends the latest `next` from any of the signals.
 ///
 /// Returns a signal that passes through values from each of the given signals,

ReactiveCocoaFramework/ReactiveCocoa/RACSignal+Operations.m

@@ -458,6 +458,12 @@ + (RACSignal *)combineLatest:(id<NSFastEnumeration>)signals reduce:(id (^)())red
 	return [result setNameWithFormat:@"+combineLatest: %@ reduce:", signals];
 }
 
+- (RACSignal *)mergeWith:(RACSignal *)signal {
+	return [[RACSignal
+		merge:@[ self, signal ]]
+		setNameWithFormat:@"[%@] -mergeWith: %@", self.name, signal];
+}
+
 + (RACSignal *)merge:(id<NSFastEnumeration>)signals {
 	NSMutableArray *copiedSignals = [[NSMutableArray alloc] init];
 	for (RACSignal *signal in signals) {

ReactiveCocoaFramework/ReactiveCocoaTests/RACSignalSpec.m

@@ -1469,6 +1469,32 @@
 	});
 });
 
+describe(@"-mergeWith:", ^{
+	__block RACSubject *sub1;
+	__block RACSubject *sub2;
+	__block RACSignal *merged;
+	beforeEach(^{
+		sub1 = [RACSubject subject];
+		sub2 = [RACSubject subject];
+		merged = [sub1 mergeWith:sub2];
+	});
+
+	it(@"should send all values from both signals", ^{
+		NSMutableArray *values = [NSMutableArray array];
+		[merged subscribeNext:^(id x) {
+			[values addObject:x];
+		}];
+
+		[sub1 sendNext:@1];
+		[sub2 sendNext:@2];
+		[sub2 sendNext:@3];
+		[sub1 sendNext:@4];
+
+		NSArray *expected = @[ @1, @2, @3, @4 ];
+		expect(values).to.equal(expected);
+	});
+});
+
 describe(@"+merge:", ^{
 	__block RACSubject *sub1;
 	__block RACSubject *sub2;