fix(jest-canvas-mock): improve constructor for dom matrix

__tests__/classes/DOMMatrix.js

@@ -16,6 +16,12 @@ describe('DOMMatrix class', () => {
     expect(matrix.f).toBe(6);
   });
 
+  it('should accept a DOMMatrix as parameter', () => {
+    const matrix = new DOMMatrix([1, 2, 3, 4, 5, 6]);
+    const matrix2 = new DOMMatrix(matrix);
+    expect(matrix2).toBeInstanceOf(DOMMatrix);
+  });
+
   it('should be a 3d matrix if constructed without a parameter', () => {
     const matrix = new DOMMatrix();
     expect(matrix.is2D).toBeFalsy();

src/classes/DOMMatrix.js

@@ -42,6 +42,9 @@ export default class DOMMatrix {
   m44 = 1.0;
 
   constructor(transform) {
+    if (transform instanceof DOMMatrix) {
+      return transform;
+    }
     if (transform && transform.length === 6) {
       this.m11 = transform[0];
       this.m12 = transform[1];

types/index.d.ts

@@ -1,4 +1,4 @@
-export function setupJestCanvasMock(window?: Window): void
+export function setupJestCanvasMock(window?: Window): void;
 
 export interface CanvasRenderingContext2DEvent {
   /**