Fixed midpoint and added some tests

framer/Layer.coffee

@@ -520,12 +520,14 @@ class exports.Layer extends BaseClass
 			x: @midX
 			y: @midY
 		set: (input) ->
-			if input.x?
-				input.midX = input.x
-				delete input.x
-			if input.y?
-				input.midY = input.y
-				delete input.y
+			if not _.isNumber input
+				input = _.pick(input, ["x", "y", "midX", "midY"])
+				if input.x? and not input.midX?
+					input.midX = input.x
+					delete input.x
+				if input.y? and not input.midY?
+					input.midY = input.y
+					delete input.y
 			input = layerPropertyPointTransformer(input, @, "midPoint")
 			@_setGeometryValues(input, ["midX", "midY"])
 

test/tests/LayerTest.coffee

@@ -1544,6 +1544,46 @@ describe "Layer", ->
 				layerA.x.should.equal 137
 				layerA.y.should.equal 283
 
+	describe "midPoint", ->
+		it "should accept a midX/midY value", ->
+			l = new Layer
+				midPoint:
+					midX: 123
+					midY: 459
+			l.midX.should.equal 123
+			l.midY.should.equal 459
+		it "should accept a x/y value", ->
+			l = new Layer
+				midPoint:
+					x: 123
+					y: 459
+			l.midX.should.equal 123
+			l.midY.should.equal 459
+
+		it "should accept a single number", ->
+			l = new Layer
+				midPoint: 234
+			l.midX.should.equal 234
+			l.midY.should.equal 234
+		it "should pick midX/midY over x/y", ->
+			l = new Layer
+				midPoint:
+					midX: 123
+					midY: 459
+					x: 653
+					y: 97
+			l.midX.should.equal 123
+			l.midY.should.equal 459
+		it "should not change the object passed in", ->
+			l =
+				x: 100
+				y: 200
+			m = new Layer
+				midPoint: l
+			m.midX.should.equal l.x
+			m.midY.should.equal l.y
+			l.x.should.equal 100
+			l.y.should.equal 200
 	describe "CSS", ->
 
 		it "classList should work", ->