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4.44 Elementary Method "White Box Test Case Design" (WBTD)  

  4.44 Elementarmethode "White-box-Testfallentwurf" (WBTE)

Contents  
  • 1 Identification/Definition of the Method
  • 2 Brief Characteristic of the Method
  • 3 Limits of the Methods Application
  • 4 Specification of the Methods Allocation
  • 5 Interfaces
  • 6 Further Literature
  • 7 Functional Tool Requirements
  • Links to the V-Model Mailinglist
  • 1 Identification/Definition of the Method

    /Myers, 1991/ chap. 2, pp. 8-9; chap. 4, pp. 36-44

    2 Brief Characteristic of the Method

    Objective and Purpose

    The objective of the "White Box Test Case Design" (WBTD) is to detect errors by means of execution-oriented test cases.

    Operational Sequence

    White Box Testing is a test strategy which investigates the internal structure of the object to be assessed in order to specify execution-oriented test cases on the basis of the program logic. In this connection the specifications have to be taken into consideration, though. In a test case design, the portion of the assessed object which is addressed by the test cases is taken into consideration. The considered aspect may be a path, a statement, a branch, and a condition. The test cases are selected in such a manner that the correspondingly addressed portion of the assessed object is increased.

    The following White Box Test Case methods exist:

  • path coverage
  • statement coverage
  • branch coverage
  • condition coverage
  • branch/condition coverage
  • coverage of all multiple conditions
    1. Path Coverage

      Objective and Purpose
      It is the objective of the path coverage to identify test cases executing a required minimum number of paths in the object to be assessed. The execution of all paths cannot be realized as a rule.

      Operational Sequence
      By taking into consideration the specification, the paths to be executed and the corresponding test cases will be defined.

    2. Statement Coverage

      Objective and Purpose
      It is the objective of the statement coverage to identify test cases executing a required minimum number of statements in the object to be assessed.

      Operational Sequence
      By taking into consideration the specification, statements are identified and the corresponding test cases are defined. Depending on the required coverage degree, either all or only a certain number of statements are to be used for the test case definition.

    3. Branch Coverage

      Objective and Purpose
      It is the objective of the branch coverage to identify test cases executing a required minimum number of branches, i. e. at least once in the object to be assessed.

      Operational Sequence
      By taking into consideration the specification, a sufficiently large number of test cases must be designed by means of an analysis so both the THEN and the ELSE branch are executed at least once for each decision. I. e. the exit for the fulfilled condition and the exit for the unfulfilled must be utilized and each entry must be addressed at least once. For multiple decisions there exists the additional requirement to test each possible exit at least once and to address each entry at least once.

    4. Condition Coverage

      Objective and Purpose
      The objective of the condition coverage is to identify test cases executing a required minimum number of conditions in the object to be assessed.

      Operational Sequence
      By taking into consideration the specification, conditions are identified and the corresponding test cases are defined. The test cases are defined on the basis of a path sequence analysis.

    5. Branch/Condition Coverage

      Objective and Purpose
      The objective of the branch/condition coverage is to identify test cases executing a required minimum number of branches and conditions in the object to be assessed.

      Operational Sequence
      By taking into consideration the specification, branches and conditions are identified and the corresponding test cases are defined.

    6. Coverage of all Multiple Conditions

      Objective and Purpose
      The objective of the coverage of all multiple conditions is to identify test cases executing a required minimum number of all possible condition combinations for a decision in the object to be assessed.

      Operational Sequence
      By taking into consideration the specification, condition combinations for decisions are identified and the corresponding test cases are defined. When defining test cases it must be observed that all entries are addressed at least once.

    3 Limits of the Methods Application

    Method White Box Test Case Design can only be properly applied if tool support is available to measure the coverage.

    4 Specification of the Methods Allocation

    No. Activity Description
    4.1 QA2.3 - Definition of Test Cases By means of the WBTD method, assessment, i. e. test cases are defined for the following objects to be assessed:
  • Module
  • Database
  • Component
  • Subproduct Assessment Specification.Test Case Description is only completely covered by the additional application of method BBTD - Black Box Test Case Design.

    5 Interfaces

    - not applicable -

    6 Further Literature

    /Myers, 1991/ Methodisches Testen von Programmen
    /Redwine, 1983/ An Engineering Approach to Software Test Case Design
    /Sneed, 1988/ Software-Qualitätssicherung
    /Wallmüller, 1990/ Software-Qualitätssicherung

    7 Functional Tool Requirements

    SQA14 - Generation of Test Cases

    Links to the V-Model Mailinglist

    Mail 0653 - QS-Plan: Fragen zu Festlegung der Kritikalität, Vererbung, Infizierung und zughörigen Dokumenten (653)

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