What is the difference between a test plan and test strategy? Which comes first?

What is the difference between a test plan and test strategy? Which comes first?

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EXPERT RESPONSE

As usual, the answer to this question depends on whom you ask. I think James Bach describes this particularly well in his blog as follows:

"Test strategy is an important yet little-described aspect of test methodology. Let me introduce three definitions:

Test Plan: the set of ideas that guide a test project

Test Strategy: the set of ideas that guide test design

Test Logistics: the set of ideas that guide the application of resources to fulfill a test strategy

I find these ideas to be a useful jumping-off point. Here are some implications:

* The test plan is the sum of test strategy and test logistics.


* The test plan document does not necessarily contain a test plan. This is because many test plan documents are created by people who are following templates without understanding them, or writing things to please their bosses, without knowing how to fulfill their promises, or simply because it once was a genuine test plan but now is obsolete.


* Conversely, a genuine test plan is not necessarily documented. This is because new ideas may occur to you each day that change how you test. In my career, I have mostly operated without written test plans.

One quick way to think about test strategy is to realize that testing is (usually) a process of constructing an explanation of the status of the product. Therefore, the ideas that should guide our testing are those that relate to the marshalling of evidence for that explanation."

Software testing resources:
Managing the Testing Process -- Chapter 2, The Test Plan

Software testing deliverables: From test plans to status reports

Software quality and testing: Resources for beginners


So, simply put, a test strategy is about what you want to test. Test logistics are about what resources are needed to test what you want to test, the way you want to test it. A test plan couples those two items, factors in the project plan and yields how and when the testing will be accomplished.

I don't think of which comes first, I think of each of them as evolving along with the tester's understand of the application under test. But I guess if what you are really interested in is the documentation of these items, then the test strategy would come before the test plan.