Unit testing in Visual Studio 2008 Team System - part II

In previous post (http://csharpmatters.blogspot.com/2009/03/unit-testing-in-visual-studio-2008-team.html) I’ve described new test functionality in VS2008 TS.

In this post I drill down unit tests inside VS2008 more detail.

VS built-in units tests use attributes (similar to NUnit).

Attributes are used to denote various test methods and test classes.

Common attributes:

[TestClass()] mark class representing a unit test case. Class need to be public.

[TestMethod()]marks Test Method

Another popular attributes:

[ClassInitialize()] –code need to be run before running the first test in the class

[ClassCleanup()] – code need to be run after all tests in class

[TestInitialize()] – code need to be run before each test

[TestCleanup ()] – code need to be run after each test

Example:

[TestClass()]
public class MyClassTest

[TestMethod()]
public void MyClassInitTest()

VS provides Assert class with static methods to check various conditions.

All Asserts methods accept 2 parameters: Boolean condition and exception message provided by user. If condition is FALSE: test exception with custom msg is thrown.

More about assert methods here: http://msdn.microsoft.com/en-us/library/microsoft.visualstudio.testtools.unittesting.assert_members.aspx

If you worked with nUnit tool you can see a lot of similarities.

(Please note UI testing is not supported in the current version of unit testing with VS.NET 2008)

Let’s follow nUnit example (http://www.nunit.org/index.php?p=quickStart&r=2.4.7) but using VS built-in tests this time.

Production code example:
<br />public class Account<br /> {<br /> #region Members<br /> private float balance; <br /> #endregion Members<br /><br /><br /> #region Properties<br /> public float Balance {<br /> get { return balance; }<br /> } <br /> #endregion Properties<br /><br /> #region Public Methods<br /> public void Deposit ( float amount ) {<br /> balance += amount;<br /> }<br /> public void Withdraw ( float amount ) {<br /> balance -= amount;<br /> }<br /> public void TransferFunds ( Account destination, float amount ) {<br /> }<br /> #endregion Public Methods<br /><br /> }<br />

Test Class code:
<br /><br />namespace UnitTests<br />{<br /> /// <summary><br /> ///This is a test class for AccountTest and is intended<br /> ///to contain all AccountTest Unit Tests<br /> ///</summary><br /> [TestClass ()]<br /> public class AccountTest {<br /><br /> private TestContext testContextInstance;<br /><br /> /// <summary><br /> ///Gets or sets the test context which provides<br /> ///information about and functionality for the current test run.<br /> ///</summary><br /> public TestContext TestContext {<br /> get {<br /> return testContextInstance;<br /> }<br /> set {<br /> testContextInstance = value;<br /> }<br /> }<br /> /// <summary><br /> ///A test for TransferFunds<br /> ///</summary><br /> [TestMethod ()]<br /> public void TransferFundsTest() {<br /> Account source = new Account (); <br /> source.Deposit(200F);<br /><br /> Account destination = new Account();<br /> destination.Deposit(150F);<br /><br /> // Call tested method<br /> source.TransferFunds ( destination, 100F );<br /><br /> // Perform checks<br /> Assert.AreEqual( 250F, destination.Balance);<br /> Assert.AreEqual( 100F, source.Balance);<br /> }<br /> }<br />}<br /><br /><br />

After test run you will see that test failed with message:

TransferFundsTest UnitTests Assert.AreEqual failed. Expected:<250>. Actual:<150>.

All because production method TransferFunds() has no implementation yet.

Let’s correct that as follows:

public void TransferFunds ( Account destination, float amount ) {

destination.Deposit( amount );

Withdraw(amount);

}

After that correction test is passed.

Please find more about testing in next part(s) of post