From 580fe7cecd07370d5dbefa1f500fe25adf8580cd Mon Sep 17 00:00:00 2001
From: Joost De Cock <joost@decock.org>
Date: Sun, 24 Feb 2019 13:00:55 +0100
Subject: [PATCH] :bug: Fixed issue with point.flipX/Y breaking when passing
 zero

---
 src/point.js        |  4 ++--
 tests/point.test.js | 16 ++++++++++++++--
 2 files changed, 16 insertions(+), 4 deletions(-)

diff --git a/src/point.js b/src/point.js
index 2120140181e..310d6919a1e 100644
--- a/src/point.js
+++ b/src/point.js
@@ -73,13 +73,13 @@ Point.prototype.copy = function() {
 
 /** Mirrors this point around X value of that point */
 Point.prototype.flipX = function(that = false) {
-  if (that === false) return new Point(this.x * -1, this.y);
+  if (that === false || that === 0) return new Point(this.x * -1, this.y);
   else return new Point(that.x + this.dx(that), this.y);
 };
 
 /** Mirrors this point around Y value of that point */
 Point.prototype.flipY = function(that = false) {
-  if (that === false) return new Point(this.x, this.y * -1);
+  if (that === false || that === 0) return new Point(this.x, this.y * -1);
   else return new Point(this.x, that.y + this.dy(that));
 };
 
diff --git a/tests/point.test.js b/tests/point.test.js
index 7725c54879d..534bd47cc60 100644
--- a/tests/point.test.js
+++ b/tests/point.test.js
@@ -50,24 +50,36 @@ it("Should check points for equality", () => {
   expect(a).to.deep.equal(b);
 });
 
-it("Should flip point around X value zero", () => {
+it("Should flip point around unset X value", () => {
   let result = new Point(2, 4).flipX();
   expect(result.x).to.equal(-2);
   expect(result.y).to.equal(4);
 });
 
+it("Should flip point around X value that is zero", () => {
+  let result = new Point(2, 4).flipX(0);
+  expect(result.x).to.equal(-2);
+  expect(result.y).to.equal(4);
+});
+
 it("Should flip point around X value", () => {
   let result = new Point(2, 4).flipX(new Point(-20, 19));
   expect(result.x).to.equal(-42);
   expect(result.y).to.equal(4);
 });
 
-it("Should flip point around Y value zero", () => {
+it("Should flip point around unset Y value", () => {
   let result = new Point(2, 4).flipY();
   expect(result.x).to.equal(2);
   expect(result.y).to.equal(-4);
 });
 
+it("Should flip point around Y value that is zero", () => {
+  let result = new Point(2, 4).flipY(0);
+  expect(result.x).to.equal(2);
+  expect(result.y).to.equal(-4);
+});
+
 it("Should flip point around Y value", () => {
   let result = new Point(2, 4).flipY(new Point(12, -14));
   expect(result.x).to.equal(2);