Key Difference: A test strategy outlines the testing approach that the company aims to take.  The purpose of a test strategy is to inform project managers, testers, and developers about some of the key issues of the testing process. A test plan, on the other hand, is a detailed document which lists the systematic approach to testing the system. Its aim is to map out the detailed understanding of the workflow.

In any project, testing is an integral aspect of the process. Testing is a way to make sure that the project is up to standards. In order to ensure quality and the proper testing methods, the company usually draws up papers documenting the process of the project. These documents also serve as proof that the project has complied with any and all required testing methods. Test strategy and test plan are two such documents that the company draws up.

A test strategy outlines the testing approach that the company aims to take.  The purpose of a test strategy is to inform project managers, testers, and developers about some of the key issues of the testing process. The test strategy incorporates the testing objective, methods of testing new functions, total time and resources required for the project, and the testing environment. Essentially, the test strategy includes which types of test are to be performed, and which entry and exit criteria apply. A test strategy should be created for every corresponding stage of development design.

A test plan, on the other hand, is a detailed document which lists the systematic approach to testing the system. Its aim is to map out the detailed understanding of the workflow. It is a document prepared by the test engineers, which will be used to verify and ensure that the product meets its design specifications and requirements.

The main difference between the two is their scope. The test strategy is a mere outline of the entire project testing. It covers the general views and objectives that the project should achieve, in addition to the approaches that should be use to achieve them. It is usually a project-wide document that is shared with the entire project team and/or the whole company.

The test plan is more detailed. It incorporates a lot of the specifics of that which has been outlined in the test strategy, such as who does the actual testing and how the steps are to be conducted. However, it will always follow the guidelines as stated in the test strategy. The test plan may deal with the entire project as a whole or a specific part of the project. In some smaller projects, the test strategy can also be found as a section of the test plan.

Furthermore, the test strategy is a static document, i.e. it is the same throughout the project from the beginning to the end. However, the test plan may often be revised in face of unforeseen circumstances faced by the project. Hence, it is versatile.

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