Add assertions to check we have the blue border

RebelTests/RBLResizableImageSpec.m

@@ -11,6 +11,7 @@
 SpecBegin(RBLResizableImage)
 
 __block RBLResizableImage *testImage = nil;
+__block void(^expectBlueBorder)(NSBitmapImageRep* imageRep, NSSize size) = nil;
 
 beforeEach(^{
 	NSURL *testImageURL = [[NSBundle bundleForClass:self.class] URLForResource:@"<RBLResizableImageSpec>_testimage" withExtension:@"tiff"];
@@ -20,6 +21,35 @@ beforeEach(^{
 	testImage = [[RBLResizableImage alloc] initByReferencingURL:testImageURL];
 
 	expect(testImage).toNot.beNil();
+	
+	expectBlueBorder = ^(NSBitmapImageRep *imageRep, NSSize size) {
+		NSUInteger topLeft[4], bottomRight[4];
+		
+		// confirm we have the borders
+		[imageRep getPixel:&topLeft[0] atX:0 y:0];
+		
+		NSUInteger red = topLeft[0];
+		NSUInteger green = topLeft[1];
+		NSUInteger blue = topLeft[2];
+		NSUInteger alpha = topLeft[3];
+		
+		expect(red).to.equal(0);
+		expect(green).to.equal(0);
+		expect(blue).to.equal(255);
+		expect(alpha).to.equal(255);
+
+		[imageRep getPixel:&bottomRight[0] atX:(NSUInteger)(size.width - 1) y:(NSUInteger)(size.height - 1)];
+
+		red = bottomRight[0];
+		green = bottomRight[1];
+		blue = bottomRight[2];
+		alpha = bottomRight[3];
+		
+		expect(red).to.equal(0);
+		expect(green).to.equal(0);
+		expect(blue).to.equal(255);
+		expect(alpha).to.equal(255);
+	};
 });
 
 it(@"should use @1x asset in @1x context", ^{
@@ -49,6 +79,8 @@ it(@"should use @1x asset in @1x context", ^{
 	expect(green).to.equal(0);
 	expect(blue).to.equal(0);
 	expect(alpha).to.equal(255);
+	
+	expectBlueBorder(bitmapImageRep, targetSize);
 });
 
 it(@"should use @2x asset in @2x context", ^{
@@ -78,6 +110,8 @@ it(@"should use @2x asset in @2x context", ^{
 	expect(green).to.equal(255);
 	expect(blue).to.equal(0);
 	expect(alpha).to.equal(255);
+	
+	expectBlueBorder(bitmapImageRep, targetSize);
 });
 
 SpecEnd