Tips for Writing Test Cases for Coffee Machines

Coffee machines are like minicomputers today. Many have complex user interfaces that enable users to create different types of coffee, choose a size, add extra ingredients, or even set a temperature range. 

Smart coffee machines also tell you when the coffee is low, the water tank needs cleaned, or filters need changing. 

Coffee vending machines use software code to perform tasks. Software code requires full test coverage to ensure customer satisfaction. 

Test cases for coffee machines need to verify that functionality meets requirements. 

This guide provides samples of test cases for coffee machines, including functional, usability, user interface, boundary conditions, and negative test scenarios. 

Functional Test Cases For A Coffee Vending Machine

What types of test cases for coffee machines verify functionality? Consider using basic test case techniques to create every kind of test case. Use the functional requirements and the following functional test case samples to get started.

1. Fill the water, beans, and additives (creamer or milk) to the expected level. 
   • Press the large coffee button with no additives. 
     1. Verify any indicator lights show the machine is brewing. 
     2. Verify a large coffee cup dispenses into the filling space. 
     3. Confirm the indicator lights let the user know when the coffee is ready. 
   • Verify the coffee fills as expected in the cup and the machine resets to receive a new order. 
     1. Confirm there are no additives. 
     2. Use a thermometer to confirm the temperature matches requirements. 

2. Fill the water, beans, and additives (creamer or milk) to the expected level. 
   • Ensure the unit is plugged in or has access to a power source. 
   • Press the large coffee button and add two or more creams. 
     1. Verify any indicator lights show the machine is brewing. 
     2. Verify a large coffee cup dispenses into the filling space. 
     3. Confirm two cream additives are added after the coffee. 
     4. Confirm the indicator lights show when the order is complete. 
   • Verify the coffee fills as expected in the cup, and that the machine resets to receive a new order. 
     1. Use a thermometer to confirm the temperature matches requirements.

3. Select the ON button to activate the automatic cleaner. 
   • Confirm the machine indicates the coffee, additives, and water reservoirs are empty. 
   • Verify that an indicator light shows the machine is locked for cleaning. 
     1. Try to press the coffee button for any size coffee.
     2. Verify the system shows a message indicating it is in cleaning mode. 
   • Time the cleaning process. 
     1. Verify the time it takes to clean meets requirements automatically. 
   • Once the automatic cleaning process is completed, inspect the machine. 
     1. Verify the cup dispenser is full. 
     2. Verify the water dispenser is clean and empty. 
     3. Verify the coffee dispenser is clean and empty. 
     4. Verify the additive dispensers are clean and empty. 
   • Confirm the machine resets after cleaning to indicate the user must fill the ingredients before brewing coffee. 

4. Fill all ingredients after cleaning. 
   • Select the ON button to brew a large cup of coffee with one cream and one sugar. 
     1. Verify an indicator light shows the machine is brewing. 
     2. Verify a large coffee cup dispenses into the filling space. 
     3. Confirm one cream additive and one sugar are added after the coffee. 
     4. Confirm the indicator lights show when the order is complete. 
   • Verify the coffee fills as expected in the cup and the machine resets to receive a new order. 
     1. Use a thermometer to confirm the temperature matches requirements.
5. Fill the coffee dispenser, not the cups, additives, or water dispenser. 
   • Select a large coffee with one cream and one sugar. 
   • Verify an indicator light displays with a message that the machine is out of cups, additives, and water.  Click the option to contact the operator. 
     1. Verify an SMS message is sent to the coffee machine operator to indicate it needs service. 
   • Verify the machine shows a message apologizing for the inconvenience. 
   • Confirm the machine does NOT dispense coffee without all ingredients present.

Usability Test Cases For Coffee Vending Machine

Usability test cases for coffee machines are intended to ensure the user can successfully receive a cup of coffee at an accurate temperature and with any added ingredients at the size selected without issue. Need more test design options for non-functional tests? Consider different approaches to design. 

1. Verify users can quickly locate the ON and OFF buttons.
   1. Turn the machine OFF. 
   2. As a user, determine how easy or difficult it is to locate the ON button.
2. Verify the user’s coffee cup is full when service is complete. 
   1. Brew each available size of coffee. 
   2. After service is complete, verify the cup is full to meet requirements (¼ inch below the rim, for example). 
3. Verify the machine displays an understandable error message for:
   1. No cup inventory
   2. Any ingredient is empty
   3. Machine requires service
   4. The user selects a non-supported additive number 
4. Confirm the images and indicator lights match standards (green for ON or Ready, red for Error)
   1. View the indicator light colors when using the machine. 
      1. Verify when an error exists the light is red (or per requirements).
      2. Verify when the system is functioning then the light is green (or per requirements). 

User Interface Test Cases For Coffee Machine

User interface test cases for coffee machines intend to identify defects in functionality based on UI controls.

1. Verify button lights, images, or text match requirements for each function.
2. Verify the button indicators and lights exist for notifying users when ingredients are missing.
3. Confirm the correct brand and logo display according to requirements.
4. Verify the machine generates an error when it is plugged into an improper voltage power source. 

Boundary Conditions Test Cases For Coffee Vending Machine

Test cases for coffee machines must include verifying the machine operates with variances in values for all options: coffee, size, additives, and temperature. 

1. Verify users receive a single serving for each coffee serving. 
2. Verify when users press the coffee button repeatedly, users receive a single serving. 
3. Verify users are limited to 0-6 additive servings.
4. Verify machine accepts only supported chip credit cards. 

Negative Test Cases For A Coffee Vending Machine

Negative test cases for coffee machines are intended to identify defects when a user acts out of the expected sequence. 

1. Press large and small coffee buttons at the same time. 
   • Verify only the first selection is fulfilled. 
2. Overfill the coffee beans and push the brew button. 
   • Verify the machine indicates an error with a red indicator light and a message that says the coffee beans are overfull. 
3. Turn the machine off and then press the coffee button. 
   • Verify the machine does not respond without power. 
4. Turn the machine on its side and try to press the coffee button. 
   • Verify the machine displays an error that it is not upright and cannot function. 

How to Automate Test Cases in Testsigma

If you are a tester who creates test cases, you also will need to know how to automate those at some point of time. Testsigma is a low-code test automation platform that makes it very easy to learn and start with automating and executing test cases.

Leverage Generative AI (Gen-AI) technology by automating test cases using Testsigma. 

Testsigma users can also perform test management, bug tracking, and test development in Testsigma. Get started with Testsigma using a free trial of the cloud-based tool. 

Most organizations start by creating test cases: 

Next, organize tests into new test suites for easier tracking and status reporting:

Write your automated scripts. Visit the test automation guide for creating automated scripts with Testsigma.

Conclusion

Testing coffee machine computer interfaces can be challenging. By understanding how to write test cases for coffee machines, testers can create full suites of effective, concise, and thorough test coverage. 

Testing is more than proving functionality works, quality test cases also verify functionality through usability, user interface, boundary conditions, and negative test cases. Consider using Testsigma to automate test cases and leverage the power of AI for analytics, reporting, test development, and even maintenance.