Unit Testing

1
Unit Testing

• "Beware of bugs in the above code I have only
  proved it correct, not tried it."
• Donald E. Knuth, March 29, 1977 in a note to
  Peter van Emde Boas titled
• Notes on the van Emde Boas construction of
  priority deques An instructive use of recursion

2
Unit Test What is it?

• A unit test is a method used to verify that
  particular small unit of code (class) is working
  properly.
• Each test case is separate from the others so
  that only the functions provided by the class are
  evaluated.

3
Unit Test Characteristics

• AutomaticRequires neither intervention nor
  manual setup
• ThoroughCovers all important functionality,
  including protected and private methods. Boundary
  conditions should be checked.
• RepeatableTests run with the same data return
  the same results.

4
Unit Test Characteristics

• IndependentEach test is independent of the
  results of previous tests and do not affect later
  tests.
• PerformantPerformance is good enough to support
  running many tests at one session.

5
Unit Test Terminology

• A Test Fixture is a public instance class having
  the TestClass attribute.
• A Test is a non-static public method returning
  void, accepting no parameters and having the Test
  attribute.
• A Test Context is an instance of the TestContext
  class that persists throughout the life of a test
  fixture.

6
Unit Test Terminology

• The Unit Test Runner is the code that
  instantiates test fixtures, executes tests within
  the fixture capturing output and exceptions
  (assertions).
• The Visual Studio Test Manager manages lists of
  tests and fixtures to be submitted to the test
  runner.

7
Unit Test Lifecycle
8
Unit Test Lifecycle
9
Unit Test Lifecycle
10
Life Cycle of a Unit Test Fixture

• An instance of the unit test runner is created
  (either through VS or MSTest)
• The test runner loads the test fixture and
  inspects the test attributes using reflection.
• From the test information, a test context
  instance is created. This instance exists
  throughout the life of the text fixture.
• The assembly and class initialize methods are
  called (static methods with AssemblyIntitialize
  and ClassInitialize attributes).

11
Life Cycle of a Unit Test Fixture

• For each test (method) in the fixture, the
  following RUN procedure occurs
• An instance of the test fixture is created.
• A copy of the test context is passed to the
  fixture instance. Instance information is now in
  the test context.
• The initialize method is called (a method with
  the TestInitialize attribute).
• The test method is invoked
• The cleanup method is called (a method with the
  TestCleanup attribute).

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Life Cycle of a Unit Test Fixture

• When all tests have run (or until the runner
  terminates)
• The class cleanup method (a static method with
  the ClassCleanup attribute) is called.
• The assembly cleanup method (a static method with
  the AssemblyCleanup attribute) is called.

13
Life Cycle of a Unit Test Fixture

• If the test has a data source associated with it,
  then the following occurs
• While there are more rows in the data source,
  populate the DataRow property with the next row
  in the data source and then execute the RUN
  procedure.
• If a test throws an exception (via an assertion
  or otherwise), the test is terminated with a
  failure.

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Testing Non-Public Methods

• Visual Studio uses reflection to create accessor
  classes the file is VSGenCodeAccessors.cs do
  not modify!
• It has the same namespace as your test container
  (test project)
• Modify Visual Studio generated code within your
  test method for readability.

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Testing Non-Public Methods

• Create a instance of your class using the public
  constructor.
• Pass the object to accessor constructor.
• Call methods on the returned accessor.

_matrix new Matrix(new Collectionltstringgt(heade
rLabels)) Digatto_Covering_Dlx_MatrixAccessor
matrix new Digatto_Covering_Dlx_MatrixAccessor(_
matrix) matrix.PopulateRow(new
Collectionltstringgt(new string "C", "E", "F"
))
16
Best Practices

• Use the test context to store information that
  must be shared by different tests. The Properties
  property returns an IDictionary
  object.TotalAgents1
• ControllerNameBXLEVARO
• AgentWeighting100
• AgentNameBXLEVARO
• TestDeploymentDirC\Documents and
  Settings\richard.levaro\Local Settings\Application
  Data\VSEqtDeploymentRoot\f4e70d35-26e9-4c28-96c9-
  9a1891bf72bc\Out
• AgentId1
• TestLogsDirC\Documents and Settings\richard.leva
  ro\Local Settings\Application Data\VSEqtDeployment
  Root\f4e70d35-26e9-4c28-96c9-9a1891bf72bc\In\BXLEV
  ARO
• TestDirC\Documents and Settings\richard.levaro\L
  ocal Settings\Application Data\VSEqtDeploymentRoot
  \f4e70d35-26e9-4c28-96c9-9a1891bf72bc
• TestNameAddBookTest
• To include output in the test details, use the
  WriteLine method of the test context.
• Use the initialize and cleanup methods

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Best Practices

• Dont test the framework (or Hibernate)
• Do test your algorithms create mock objects if
  necessary
• Do use unit testing as software scaffolding
  during development and then migrate to a unit
  test
• Dont test trivia (Properties that dont do
  anything)

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Best Practices

• Visual Studio places the test project in the same
  location as the source.
• Create the test project first and then add tests
  to it.
• Use the Test Tools toolbar

19
Integration with Team Suite

• MSTest allows unit tests to be run as part of the
  build project.
• Create work items based upon failed results.

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Documentation
Microsoft.VisualStudio.TestTools.UnitTesting

• Contains all documentation for Assert methods
• Attribute documentation
• Found in Team Test API under Team Edition for
  Testers
• Other namespaces implement load testing, Web
  testing and others

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Theres More

• Data-driven tests and how to create them
• Code coverage
• Detailed Team System integration publishing
  test results