Test Case vs. Test Scenario: Key Differences to Note for Software Developers

Test cases and test scenarios are two of the most common test artifacts: both are documentation produced by the software development team in order to track progress on a project. 

With the current shift away from the Waterfall method of software development and towards Agile testing, it is important to understand the differences between test cases and test scenarios. But it is also important to note that the methods are most valuable when used together appropriately.

It’s worth noting that test cases often form part of a test scenario. A test scenario is focused on an aspect of the project — for instance, "test the login function." Test cases are your means of checking if that aspect works as intended — in this case, that would be detailing the steps to take.

The two techniques are usually used together but can be used separately depending on the resources available. We’ve outlined some key differences to note so that you can choose which testing method to use for each project or whether to use a combination of the two. 

The Test Scenario Process

When checking specific features, there is no ambiguity. The steps and expected results are clearly defined, and any deviation from the expected process/results is considered a failure. In contrast, a test scenario tends to have a less detailed plan, with no specific steps and simply an end goal. This means that the process is more open to creativity on the part of the QA team.

Test scenario examples:

• Checking the downloads on your website work correctly
• Ensuring the payments function on your e-commerce site works
• Testing the ability to log in to the site

The Test Case Process

Test cases can be useful as part of testing in production so that you can take a close look at the steps required for the product to function in a real-life environment. Whereas a scenario is a general overview of what to assess, test cases consist of particular, detailed instructions. 

Let's consider a test case process example. If you were testing the payment functionality of a website, your instructions may include steps like the ones below:

• Check the response to the valid card number and valid card expiry date
• Check the response to the valid and invalid card expiry date
• Check the response to the invalid card number and valid card expiry date
• Check the response to the invalid card number and invalid card expiry date
• Check the response to leaving the card number field blank

And so on.

Format

Because test scenarios usually have one simple goal, the means of getting to that goal is more flexible than in test cases (where the process is more specific). The test documents will reflect these differences.

A test case document will have specific guidelines for every case: the test case name, pre-conditions, post-conditions, description, input data, test steps, expected output, actual output, results, and status fields will all be laid out in the case document.

For example, if you are testing the "login" feature on your app, the pre-conditions might be a user-created account, the description might be "successful login," test steps might be "input user name and password," and the expected output "directed to the homepage."

In contrast, a test scenario document is open to interpretation by the team. They should identify the most important goal of the project and then design tests around reaching that goal. Test case scenarios allow for creativity on the part of the testers.

Perspective

Test scenarios view the project through a more dynamic, creative lens. They tend to encourage testers to think about and discuss the project and potential improvements. For example, localization testing doesn’t only involve the technical success of the project but also the cultural and linguistic features necessary for a project to be successful in a particular area. In this case, a test scenario might provide a better lens than thorough test cases.

Scenarios enable the QA team to think beyond set instructions and find problems they might not otherwise encounter. Test cases are less about realizing the potential of the project and more about documenting what the project has already achieved.

Focus

Test scenarios focus on “what to test,” and the higher-level functional specifications of the project. However, test cases focus not only on “what to test,” but also on “how to test.” Test scenarios are focused on results, whereas test cases place equal importance on the means of achieving those results.

Test scenarios are quicker than test cases, and as such can be used as a tool for progress updates for the client, and to help ensure that the project aligns with the business processes. Because they are focused on overall functionality, test scenarios can help define the most critical parts of the system. Running test scenarios first to check the overall functionality of the project can then inform the design of your test cases.

Test cases focus on the details of the project: they test the steps that lead towards the overall goal. Because test cases are both methodical and specific, they are useful for uncovering issues at specific points in the system, tracking and fixing bugs, or meeting specifications such as becoming ISO certified.

Resources

Test scenarios are derived from use cases, with a focus on the interactions that the end-user will have with the application. Test cases might also be based on use cases, but they will also draw on any test scenarios already run, and one specifically designed criteria 

Typically, test cases require more time and resources to run because they are so in-depth. They test every feature of a project and document it, but this necessarily takes time and requires a larger workforce. This means test cases are a good choice for big-budget projects with many intricate parts. With a small team, it may be more worthwhile focusing on test scenarios than shelling out for the time and labor required for accurate test cases.

On the other hand, test scenarios use fewer resources since they only test the end results of the project. This makes test scenarios a good choice when projects are pushed for time, or when the project is simple enough that it does not have myriad specific elements that need testing.

Test Case vs. Test Scenario

Both test cases and test scenarios are useful tools for software development. Test cases offer a more in-depth look at specific features of the product, while test scenarios consider the success of the product as a whole. In time-sensitive situations, test scenarios might be preferable because they require fewer resources. However, test cases are more thorough at pinpointing bugs.

Whatever you choose, it’s important to be aware of why you’ve made the choice. Make sure it fits with your overall development ethos and will help you get the results you want.