Several manufacturers of imaging-related products provide online resources that can be helpful for evaluating monitors, particularly those that will be used for printing photographs. Eizo in Belgium has a very comprehensive test that will show up defective pixels, uniformity, colour gamma and separations, sharpness, viewing angle and response time. You can select any parameter individually or use the default setting, which will run through all the tests. The test is available at https://www.eizo.be/monitor-test/.
On-screen testing can be useful but to be really sure your monitor is displaying the hues and tones you need for printing, you should compare a printed photograph with the image displayed on the screen. If your image editor supports soft proofing it will simulate the image hues and tones to show how the image will look…