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Testing Strategies

Integration testing

  • 3 things to know
  • A2 Unit 1

Overview

Integration testing, one advantage and one disadvantage of the top-down approach and one advantage and one disadvantage of the bottom-up approach.

What you need to know

Answer each one before you reveal it.

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Key term

Name three kinds of fault that only integration testing can find.

Key term

Why do modules that each pass their own tests still fail when combined?

Evaluation

State one advantage and one disadvantage of the top-down approach to integration testing

Questions from this subtopic

Each one with the model answer underneath.

  1. 1

    What is integration testing?

    Model answer

    Integration testing combines modules that have each passed their own tests and checks that they work correctly together, concentrating on the data and control passed across the interfaces between them.

  2. 2

    Why do modules that each pass their own tests still fail when combined?

    Model answer

    Modules fail when combined because each was tested against its author's reading of the interface, so one may pass a date as text where the other expects a number, or assume the caller has already validated data that it has not.

  3. 3

    Name three kinds of fault that only integration testing can find.

    Model answer

    Integration testing finds parameters passed in the wrong order or the wrong units, a module that leaves shared data in a state the next module cannot handle, and two modules that both update the same record without either expecting the other.

  4. 4

    Describe top-down integration testing.

    Model answer

    Top-down integration starts with the highest-level control module and adds the modules beneath it one level at a time, using stubs to stand in for everything not yet written.

  5. 5

    State one advantage and one disadvantage of the top-down approach.

    Model answer

    The advantage of top-down integration is that a skeleton of the whole system exists early and can be demonstrated, and the disadvantage is that a large number of stubs must be written and the detailed processing is tested last.

  6. 6

    Describe bottom-up integration testing.

    Model answer

    Bottom-up integration starts with the lowest-level modules, tests them in small groups using drivers to call them, and works upwards until the top-level control module joins the last group.

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