1. Introduction
Software testing involves various terms and concepts. Among these, “test scenarios” and “test cases” are two of the most important terms.
In this tutorial, we’ll look at these terms in-depth, explaining their roles and how they complement each other in the broader context of software testing.
2. Test Scenario vs. Test Case
A test scenario encompasses all possible software behaviors about how users might use a program. Test scenarios are beneficial in the early stages of the software development life cycle when the system’s details are not fully clear. We use test cases to cover all functional requirements.
A test case, on the other hand, is a set of well-defined instructions that guide us through every single action, including inputs and expected outcomes. We use test cases when the application’s functionality is well-defined and requires detailed testing.
3. Differences
When we use test scenarios, we’re sketching out possible ways someone might use the software and how the system should respond. Test cases take us deeper, showing us the nitty-gritty details of each possible action:
The distinction between test scenarios and test cases is crucial in software testing. Each serves a specific purpose and requires a different approach. Let’s examine the main difference between them.
3.1. Definition and Scope
A test scenario is a general outline of a feature to be tested, focusing on the overall aspects of user journeys and determining what we need to test. In contrast, a test case is a comprehensive set of conditions and actions to verify a feature’s expected behavior, giving specific instructions on how to test each step.
3.2. Creation and Documentation
We create test scenarios based on user stories and requirements. Test scenarios usually require less detailed documentation, such as checklists or diagrams.
We drive test cases from these scenarios and include comprehensive documentation like preconditions, steps, expected results, and postconditions.
3.3. Purpose and Responsibility
The primary purpose of a test scenario is to ensure comprehensive coverage of user paths and outcomes. Business analysts and QA leads often take responsibility for creating these scenarios.
On the other hand, we design test cases to confirm that the system behaves as expected under specific conditions. Test engineers or QA specialists typically write them.
3.4. Execution and Result Interpretation
We don’t use test scenarios for execution but to guide the testing process. They help us in the formulation of test cases as well as to assess the breadth of testing necessary.
In contrast, we execute test cases during the testing phase, with results often based on pass/fail criteria, which provide us with quantitative data about software behavior.
3.5. Modification and Usage Frequency
We modify test scenarios less frequently, typically when there are changes in the user journey or requirements during the testing lifecycle.
On the other hand, test cases require more frequent updates. We adjust them whenever specific functionality details change, no matter how minor, to ensure our tests remain accurate and effective.
4. Examples
Let’s consider a couple of examples to understand the differences better.
4.1. E-commerce Application: Advanced Search and Filtering
Let’s start with an e-commerce application focusing on advanced search and filtering. A user story is that a customer wants advanced search options to refine product results efficiently.
We can derive a test case from this scenario: testing the search functionality using a valid product name, assuming the user is logged in and on the homepage. The steps would involve entering a valid product name into the search bar and clicking the search button, expecting products matching the search term to be displayed.
Another test case from this scenario could be searching for a product using a product category. The setup remains the same – the user is logged in and on the homepage. This time, the test case involves entering a valid product category and clicking the search button. The expected result displays all the products from the selected category.
Visually:
So, a test scenario is a broader frame for specific test cases.
4.2. Example 2: Mobile Application
Let’s consider a mobile application with a focus on login functionality. The user story is about a user wanting to log into their account to access personalized features. The test scenario covers various ways a user might attempt to log into their account on the mobile app.
A corresponding test case could be a successful login with valid credentials. The precondition here is that the user has already signed up and has valid login credentials. The test steps would involve entering the username and password and tapping the login button, expecting the user to be redirected to the dashboard.
In contrast, another test case might involve attempting to log in with invalid credentials. The precondition is the user being at the login screen, entering invalid details, and tapping the login button. The expected outcome in this case would be an error message indicating login failure.
5. When to Use Test Scenarios and Test Cases
Understanding when to use test scenarios versus cases is crucial for effective testing strategies:
| Aspect | Test Scenario | Test Case |
|---|---|---|
| Definition | High-level concept describing a feature to be tested. | Set of conditions and actions to verify a feature’s behavior. |
| Scope | Broad, covering possible sequences in a user journey. | Focused, validating specific aspects within the scenario. |
| Granularity | Less granular, more about ‘what’ to test. | Highly granular, detailing ‘how’ to test each step. |
| Creation | Based on user stories, requirements, and brainstorming. | Derived from scenarios, detailing actionable test steps. |
| Purpose | Ensures comprehensive coverage of user paths and outcomes. | Confirms that the system behaves as expected under specific conditions. |
| Documentation Required | Usually less detailed, may be in the form of checklists or diagrams. | Requires detailed documentation, including preconditions, steps, expected results, and postconditions. |
| Responsibility | Often, the responsibility of business analysts and QA leads. | Typically written by test engineers or QA specialists. |
| Test Execution | Used to guide the test process but not for execution itself. | Executed directly during the test phase to verify functionality. |
| Result Interpretation | Results are more qualitative and focused on coverage. | Results are quantitative, often pass/fail criteria. |
| Modification | Modified when there are changes in the user journey or requirements. | Modified when specific details of the functionality change. |
| Usage Frequency | Referred to often throughout the testing lifecycle. | Executed as per the test plan, possibly automated. |
| Impact Analysis | Used for understanding the impact of changes in requirements. | Used for regression testing and checking specific impacts. |
The decision to use a test scenario or case often comes down to the level of detail required and the project phase. Test scenarios are more abstract, and we use them when we need a broad understanding of the system. On the other hand, test cases are more specific and are used when the details of what will be tested are known.
6. Conclusion
In this tutorial, we discussed the differences between test scenarios and test cases, providing a clear understanding of their respective roles in software testing. We also looked at examples illustrating these concepts.
In practice, we should use both test scenarios and test cases. Test scenarios ensure complete coverage and guide the overall test strategy, while test cases provide the specific steps to carry out that strategy effectively.