How to Test a coffee/espresso maker?

Welcome back to the 5th post of my “How To Test” series. I am sorry for the long delay between my 4th “How To Test” post and this one. Anyway, the Testing Mission will continue to remain the same as I have mentioned in the very first post of this series. I would recommend you to take a look at the testing mission first before proceeding to read this post. Here I am going to generate and list out some test ideas (Not test cases) on how to test a Coffee/Espresso Maker [A coffeemaker is a kitchen appliance used to brew coffee without having to boil water in a separate container. Larger capacity machines are also available to be used in offices/malls/stores.] Coffee (the caffeine actually) is said to work as a stress buster, which relieves tension. I have not seen many testers who don’t drink coffee! This is one of the reasons why I have chosen a coffeemaker as my test object. Most of you already might have used a coffee machine at your office or elsewhere. But have you ever tried to test it? :)
Caution:1. If you are not a caffeine addict yet, don’t jump in and start drinking coffee because of this post! You might be surprised to know that I don’t drink coffee myself! The intention of this post is to try and use tester’s mentality to test some appliances of our day-to-day usage. When I was looking for such a test object, my eyes caught the Espresso machine next to my cubicle. The next moment I had my test object to start testing (generating test ideas)!
2. I won’t bear the responsibility if anything goes wrong while you try the following test ideas with your Espresso machine! Use the test ideas at your OWN risk! :)

Note: As usual, few context-based questions popped in my mind while trying to generate some test ideas to test a coffeemaker.

a) What kind of machine is it? Is it a drip coffeemaker or a percolating coffeemaker?
b) What is the tank capacity (in terms of liters) of the coffeemaker?
c) What is the pump pressure (e.g. 15 atm, 20 atm etc)?
d) What kind of method does the machine use? Steam method, Pump method or Piston Style method?
e) What is the Max electric power consumption (800W, 900W, 1100W, 1500W, etc)?
f) What is the power supply (120V, 220V etc)?

Here I am assuming that we are going to test a drip coffeemaker (that drip hot water once through the coffee grounds) that uses boiling water pump method to operate!

Test Ideas:
1. Test the structure and dimensions of the coffeemaker and see if it confirms to the specified dimensions mentioned in the user manual. [Build Verification Testing!]
2. Test if you can get the machine to work after following the user manual and assembling the machine. [Installability Testing!]
3. Test if the different parts (the switches and timers in the control panel, the thermostat that controls electricity to operate the heating element, the plug, the power cable etc) are in good condition and are usable. [Usability Testing!]
4. Plug in the power terminal and see if the LED glows. And test if the machine is actually getting power supply. Also test the current received and maximum permitted. [Usability Testing!]
5. Test if the heating element stops heating once the electrical power to the machine is turned off (either by unplugging the cable or by switching OFF the power switch on the control panel).
6. Test the performance of the machine under different room temperatures (an AC room, kitchen, roadside etc) and see if the time taken for coffee making varies largely. [Load/Localizability Testing!]
7. Test how the coffeemaker performs under different voltage conditions. Test how it is able/unable to sustain fluctuating voltage. [Reliability/Performance Testing!]
8. Test if the power consumption of the coffeemaker is measurable. It will be useless if it consumes too much of power to operate. [Scalability Testing!]
9. Switch ON the coffeemaker for a very long time (say up to 2-3 days continuously; in office usage this can be a normal scenario!) and see the result. Test if the thermostat works fine under such situation. [Stress Testing!]
10. Test the brewing time for different flavors/types of coffee. [Performance Testing!]
11. Test if the heating element boils water when you first put it in the coffee maker. Test the operational power consumption. [Functionality Testing!]
12. Test if the heating element keeps the coffee warm, once the coffee is made! Test the stand-by power consumption. [Functionality Testing!]
13. Test if the primary temperature sensor detects the coil getting too hot and cuts off the current. Also test if it turns the coil back on power when it cools down. [Security Testing!]
14. Test if the thermal fuses cut power if they sense too high a temperature. Test if they are able to cut the power in the event that the main sensor/thermostat fails. [Security Testing!]
15. Test if the one-way valve prevents the boiling water to flow back into the bucket. The one-way valve should let cold water into the boiling chamber and should force the bubbles of boiling water to flow up the tube into the coffee chamber. You might test the working of the one-way valve by blowing on the tube leading into the value and the valve should open. If you inhale through the tube, the one-way valve should block any air. [Functionality Testing!]
16. Test if when you turn on the switch, the heating element starts heating the aluminum/stainless steel made boiling chamber, and eventually the water in the tube boils.
17. Test if the boiling water rises in the pipe into the coffee chamber due to vacuum pressure and finally drips into the coffee chamber!
18. Test if the pressure with which water is pumped into the coffee chamber is sufficient enough to brew a nice cup of foaming coffee!
19. Test if coffee is actually delivered when the appropriate button is pressed!
20. Test if desired quantity of coffee is delivered when requested!
21. Test the variation in taste when different dose/variety of coffee is selected.
22. Test if appropriate amount of milk is mixed before the coffee is served.
23. Test if milk is still mixed when NO MILK option is selected.
24. Test if preset amount of sugar is actually served with a cup of coffee.
25. Test if the dispenser area is sufficiently spacious to fit in a large coffee cup. [Usability Testing!]
26. Test the operation of the coffeemaker without a load (i.e. without water, milk, sugar, coffee etc). See if it results in electrical short circuits due to over heating of the boiling chamber. [Security Testing!]
27. Test if the inner chambers are easily cleanable! Test if the drip tray is removable. [Maintainability Testing!]
28. Test if the machine can also be used to serve other beverages like tea, hot chocolate, soups etc. [Capability Testing!]
29. Test if the machine can accommodate parts from different manufacturers in case a replacement is needed in future! [Compatibility Testing!]
30. Test if the coffee inside the reservoir clogs the whole thing up if the coffeemaker is left unused for a long time! This can happen if a family leaves for a vacation having forgotten to switch off the machine, or more practically in an office after a long holiday like Xmas. Test if the machine is easily cleanable or requires meticulous cleaning under such condition [Maintainability Testing!]

These are few test ideas that came in my mind while attempting to generate ideas to test a coffeemaker. But I bet there can be lot more test ideas like these. Why don't you take this as a Testing Challenge and come back with your own test ideas? Let me (and others) know about your test ideas by leaving behind your comments. Happy Testing…

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2. How to Test a mosquito repellent?
3. How to Test a water bottle?
4. How to Test a pen?
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About Debasis Pradhan

Debasis has over a decade worth of exclusive experience in the field of Software Quality Assurance, Software Development and Testing. He writes here to share some of his interesting experiences with fellow testers.


  1. This is an excellent post, i really like your posts on test cases. \m/


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