Difference between 'task', 'scenario' and 'use case'?

Question

I am pretty much confused with these terms. I have surfed the net, but didn't find any detailed explanation. I want to know the difference between a task, scenario and a use case. And how are they related?

Answer 1

Task: A task (in layman terms) is basically a piece of work which needs to be done/accomplished. This term is not only used in Software Industry but also in other industries and organizations e.g. in Banks everyone is assigned some tasks of Teller, Approving request, opening accounts etc.

As per the business dictionary task is defined as 'The smallest identifiable and essential piece of a job that serves as a unit of work, and as a means of differentiating between the various components of a project.'

In software industry it is used for distribution of work items among team members. It can be either combination of sub-tasks (like delivering an item will involve following sub-tasks or a single work item as standalone:

1. Requirement
2. Designing
3. Coding
4. Testing
5. Reviews

it all depends that upto which level of breakup is required for tracking and accomplishing a parent task. Even in your day to day life you create tasks in the form of To-Dos either in your Laptop/ Outlook/ Sticky Notes/ Physical notes etc.

Scenario: It is the real life situation in which the end-user/customer uses/interacts with the system and came across various failures(if there are any). Hence we generally used to say Real world scenario. A scenario is therefore usually written in narrative form, perhaps with pictures and illustrations as well.

Use Case: A use case is a methodology used in system analysis to identify, clarify, and organize system requirements. The use case is made up of a set of possible sequences of interactions between systems and users in a particular environment and related to a particular goal.The use case should contain all system activities that have significance to the users. A use case can be thought of as a collection of possible scenarios related to a particular goal.

Again remember that creating both Use Cases and Scenarios is also a Task to be completed.

Refer to this link for more granular details over Use Case, Scenario and Test case.

Answer 2

For any terminology in SQA check official documentation "Standard glossary of terms used in Software Testing" v2.3. From the document we can see that:

Use case: A sequence of transactions in a dialogue between an actor and a component or system with a tangible result, where an actor can be a user or anything that can exchange information with the system.

So it is only steps of the basic workflow or extensions (shown in diagram or as a sequence of steps). It shows project skeleton and very useful to check the goals team should accomplish.

Here is an example of Use Case diagram from wiki:

Test scenario term sends to Test procedure specification (so this is more preferable) A document specifying a sequence of actions for the execution ATM of a test. Also known as test script or manual test script. [After IEEE 829]

Test scenario is a detailed sequence of steps to accomplish testing of some functionality. Commonly test scenario is written in atomic steps that is clear to everyone (even a newbie tester can study the system by executing test scenarios). Test scenario is a part of Test specification and has many Test Cases (low level actions) associated with it.

And finally lets talk about differences:

Test scenario is about detalization VS Use Case is about generalization.

Test scenario is about small part (easy to evaluate) of functionality VS Use Case is about the whole system.

Task term as it was mentioned by @Dhiman is not a specific term for software testing, so it could have very wide range of meanings.

Answer 3

TASK: A piece of work to be done or undertaken.

SCENARIO: A written outline of a plot and individual scenes.

USE CASES: In software and systems engineering, a use case is a list of actions or event steps, typically defining the interactions between a role (known in the Unified Modeling Language as an actor) and a system, to achieve a goal. The actor can be a human or other external system.

So a scenario might describe have all the details of the task that needs to be performed. Scenario might be described via a use case to explain the role of actor for achieving a goal. This can be assigned as a task to be performed to someone.

Answer 4

Task: Work Item type in TFS to identify and manage any type of work product to be produced. We don't use this term exclusively as testing-specific terminology.

Use Case: In software and systems engineering, a use case is a list of action or event steps, typically defining the interactions between a role (known in the Unified Modeling Language as an actor) and a system, to achieve a goal. The actor can be a human, an external system, or time.

Scenario Testing (we call these User Scenarios): Scenario testing is to make sure that end to end functionality of application under test is working as expected. We work closely with Marketing, Technical Support, and other internal groups to develop our User Scenarios. Expected Results are more qualitative -- does the system work for the specific user need being tested in the scenario. This type of testing is performed after the Requirement Verification has been completed.