Difference between Test Planning and Test Strategy

This is the most frequently asked question across testing practices. There is a very fine line of difference between Test Planning and Test Strategy. We can say that a test strategy is a sub-set of test planning. While test planning is a broader term, test strategy on the other hand is a very low-level descriptive guidance to carry out a specific task. Test plan covers a holistic approach to testing while test strategy covers protocols for particular testing components.

-A Test plan defines "What to test", whereas a test strategy defines "How to test".

What is Test Planning ?

Test Plan is a road map to testing. A test plan defines the blueprint or approach to testing. During test planning, the scope of testing is determined, which includes test coverage, entry and exit criteria, functional requirement, non-functional requirement, in and out of scope items are identified.
Assumptions, risks, dependencies, and testing strategy and approach are identified and described, for instance: installation, uninstallation, update testing, smoke testing, cross-platform compatibility testing, functional, user interface testing, performance, API, security testing.

Acceptance criteria are formulated. Test deliverables (test plan, test cases test report, etc.) and test schedule are identified. Formation of the testing team takes place and roles and responsibilities are determined. Test environments and test requirements are identified which include software/hardware requirement, tools needed, test data requirement. Metrics, test reporting, and defect management mechanisms and processes are described.

The following questions are answered in a test plan:

What will be the scope of testing
What will be the approach
What will be the Test coverage
Testing strategy
Features to be tested
Features not to be tested
Hardware requirement
Software requirement
Manpower requirement and resourcing
Test Scheduling
Assumptions
Risks and Dependencies
Severity and priority guidelines
Test metrics and Key performance indicators
Scope of testing is defined in test planning
Types of testing like API, compatibility, UI, functional, non-functional
Test deliverables
Test artifacts
Test environments
Risk involved
Risk mitigation
Entry criteria
Exit criteria
Responsibilities (roles and responsibilities of each member)
Staffing and training need.

What is Test Strategy ?

Test strategy is a set of guidelines or guiding principles to carry out a particular testing task. It is a subset of the test plan. It features preconditions before carrying out a particular testing task.

For e.g. What would be the strategy when a build comes for testing?

1. We might say we'll be requiring a 'Release note' mentioning the features and bug IDs addressed in the build along with other details.

2. Then we must carry out a smoke test on the build to accept it for more rigorous testing.

3. The 70% pass percentage of the smoke test would be the acceptance criteria for the build.

4. Once the build is accepted, the test case execution will begin and

5. The bugs identified will be logged in the respective project management tools.

6. A test summary report will be shared upon completion of testing.

All these low-level guidelines documented is a test strategy document.

While test planning goes hand in hand during the project planning phase and initiation of the project, test strategy on the other hand keeps evolving during the project development process and may change on a conditional basis as per the progress of the project. Test strategy is more of conditional execution of testing task - "if this then that." The test strategy document contains protocols and instructions which determine the execution of a testing task. There are numerous things that can be strategized in a software test plan. Strategizing automation plan, strategizing stress and load testing plan, Strategizing nonfunctional testing, Strategizing functional testing, and so on.
In some cases, a test strategy is defined in the test plan document itself. But in larger projects where the scope of testing is immense and lots of non-functional testing also needs to be done, in such cases, a separate test strategy document is prepared which lists down the approach and guidelines for carrying out the testing.