Test that the rendering context state is intact after a call to putImageData() On success, you will see a series of "PASS" messages, followed by "TEST COMPLETE". Checking initial state for sanity PASS ctx.fillStyle is '#ff0000' PASS imgdata[0] is 255 PASS imgdata[1] is 0 PASS imgdata[2] is 0 PASS imgdata[3] is 255 PASS imgdata[4] is 0 PASS imgdata[5] is 0 PASS imgdata[6] is 0 PASS imgdata[7] is 0 Calling putImageData() PASS imgdata[0] is 255 PASS imgdata[1] is 0 PASS imgdata[2] is 0 PASS imgdata[3] is 255 Checking if state is intact PASS ctx.fillStyle is '#ff0000' PASS imgdata[0] is 255 PASS imgdata[1] is 0 PASS imgdata[2] is 0 PASS imgdata[3] is 255 PASS successfullyParsed is true TEST COMPLETE