test: add tests for utils/mathUtils::applyTransform

Author: MasterOdin

src/utils/mathUtils.js

@@ -1,18 +1,20 @@
 // Transform point by matrix
 //
 export function applyTransform(p, m) {
-  let xt = p[0] * m[0] + p[1] * m[2] + m[4];
-  let yt = p[0] * m[1] + p[1] * m[3] + m[5];
-  return [xt, yt];
+  return [
+    p[0] * m[0] + p[1] * m[2] + m[4],
+    p[0] * m[1] + p[1] * m[3] + m[5]
+  ];
 };
 
 // Transform point by matrix inverse
 //
 export function applyInverseTransform(p, m) {
   let d = m[0] * m[3] - m[1] * m[2];
-  let xt = (p[0] * m[3] - p[1] * m[2] + m[2] * m[5] - m[4] * m[3]) / d;
-  let yt = (-p[0] * m[1] + p[1] * m[0] + m[4] * m[1] - m[5] * m[0]) / d;
-  return [xt, yt];
+  return [
+    (p[0] * m[3] - p[1] * m[2] + m[2] * m[5] - m[4] * m[3]) / d,
+    (-p[0] * m[1] + p[1] * m[0] + m[4] * m[1] - m[5] * m[0]) / d
+  ];
 };
 
 // Concatenates two transformation matrices together and returns the result.

test/utils/mathUtils.spec.js

@@ -0,0 +1,18 @@
+import * as mathUtils from '../../src/utils/mathUtils';
+import { deepStrictEqual } from 'assert';
+
+describe('mathUtils', () => {
+  describe('mathUtils::applyTransform', () => {
+    it('multiple matrixes all zeroes', () => {
+      let p = [0, 0];
+      let m = [0, 0, 0, 0, 0, 0];
+      deepStrictEqual(mathUtils.applyTransform(p, m), [0, 0]);
+    });
+
+    it('multiple matrixes', () => {
+      let p = [5, 3, 10];
+      let m = [1, 3, 2, 4, 5, 2];
+      deepStrictEqual(mathUtils.applyTransform(p, m), [16, 29]);
+    });
+  });
+});