Added an NSManagedObjectContext extension to easily create a child co…

…ntext

Proton/NSManagedObjectContext+ConvenienceAdditions.h

@@ -13,6 +13,19 @@
  */
 @interface NSManagedObjectContext (ConvenienceAdditions)
 
+/**
+ * @name Creating Child Contexts
+ */
+
+/**
+ * Creates and returns a managed object context with its `parentContext` set to
+ * the receiver.
+ *
+ * The returned context will be initialized with `NSConfinementConcurrencyType`,
+ * and will not have an undo manager by default (even on Mac OS X).
+ */
+- (NSManagedObjectContext *)newChildContext;
+
 /**
  * @name Refreshing Objects
  */

Proton/NSManagedObjectContext+ConvenienceAdditions.m

@@ -11,6 +11,15 @@
 #import "EXTScope.h"
 
 @safecategory (NSManagedObjectContext, ConvenienceAdditions)
+- (NSManagedObjectContext *)newChildContext; {
+    NSManagedObjectContext *context = [[NSManagedObjectContext alloc] initWithConcurrencyType:NSConfinementConcurrencyType];
+
+    context.parentContext = self;
+    context.undoManager = nil;
+
+    return context;
+}
+
 - (void)refreshAllObjectsMergingChanges:(BOOL)mergeChanges; {
     NSSet *objects = [self.registeredObjects copy];
 

ProtonTests/PRONSManagedObjectContextAdditionsTests.m

@@ -161,4 +161,16 @@
         expect(undoManager.canUndo).toBeFalsy();
     });
 
+    it(@"should return a child context", ^{
+        NSManagedObjectContext *childContext = [context newChildContext];
+        expect(childContext).not.toBeNil();
+        expect(childContext.parentContext).toEqual(context);
+        expect(childContext.concurrencyType).toEqual(NSConfinementConcurrencyType);
+        expect(childContext.undoManager).toBeNil();
+    });
+
+    it(@"should return unique child contexts", ^{
+        expect([context newChildContext]).not.toEqual([context newChildContext]);
+    });
+
 SpecEnd