Channels ▼


Distributed Unit Testing

Source Code Accompanies This Article. Download It Now.

Synchronization Facilities

Runner is responsible for providing synchronization mechanisms for the tests. Example 1 presents the methods in the IPNUnitServices interface. For now, it simply provides a barrier-based synchronization mechanism.

public interface IPNUnitServices
   void NotifyResult(string TestName,PNUnitTestResult result);
   void InitBarrier(string TestName, string barrier);  
   void InitBarrier(string TestName, string barrier, int Max);  
   void EnterBarrier(string barrier);

Example 1: IPNUnitServices interface.

You can initialize a barrier using Test by defining the maximum number of elements that pass through the barrier, or Test can just let Runner handle it. In the latter case, Runner assumes that all tests pass through the barrier, so it only depends on the definition made in the XML file. However, the former approach is useful when you need to define synchronization between a few participants in the test.

As Figure 3 illustrates, the barrier mechanism is a basic synchronization primitive. All tests must pass through a barrier before any of them are allowed to pass.

Figure 3: Barrier mechanism in action.

Listing One, the barrier implementation, shows that there are two important methods plus a constructor for the Barrier class. The constructor initializes the number of elements that must pass through the barrier to release it. The Enter() method is invoked when a test enters a barrier. If it doesn't enter a barrier and all of the other involved tests have gone through it, then the thread goes to sleep using a Monitor. The second method, Abandon(), is used to release barriers under fail conditions. For instance, if a test fails before hitting a barrier, Abandon() is called, so that an erroneous test won't freeze the rest of the tests.

public class Barrier
    private int mCount;
    private int mMaxCount;
    private Object mLock = new Object();
    public Barrier(int maxCount)
        mCount = 0;
        mMaxCount = maxCount;
    public void Enter()
        lock( mLock )
            if( mCount >= mMaxCount )
                mCount = 0;
    public void Abandon()
        lock( mLock )
            if( mCount >= mMaxCount )
                mCount = 0;
Listing One

With the Barrier method, we have been able to implement large test suites, covering all the basic core functionality of our system. Still, it would be easy to include some other primitives—semaphores, for instance.

Related Reading

More Insights

Currently we allow the following HTML tags in comments:

Single tags

These tags can be used alone and don't need an ending tag.

<br> Defines a single line break

<hr> Defines a horizontal line

Matching tags

These require an ending tag - e.g. <i>italic text</i>

<a> Defines an anchor

<b> Defines bold text

<big> Defines big text

<blockquote> Defines a long quotation

<caption> Defines a table caption

<cite> Defines a citation

<code> Defines computer code text

<em> Defines emphasized text

<fieldset> Defines a border around elements in a form

<h1> This is heading 1

<h2> This is heading 2

<h3> This is heading 3

<h4> This is heading 4

<h5> This is heading 5

<h6> This is heading 6

<i> Defines italic text

<p> Defines a paragraph

<pre> Defines preformatted text

<q> Defines a short quotation

<samp> Defines sample computer code text

<small> Defines small text

<span> Defines a section in a document

<s> Defines strikethrough text

<strike> Defines strikethrough text

<strong> Defines strong text

<sub> Defines subscripted text

<sup> Defines superscripted text

<u> Defines underlined text

Dr. Dobb's encourages readers to engage in spirited, healthy debate, including taking us to task. However, Dr. Dobb's moderates all comments posted to our site, and reserves the right to modify or remove any content that it determines to be derogatory, offensive, inflammatory, vulgar, irrelevant/off-topic, racist or obvious marketing or spam. Dr. Dobb's further reserves the right to disable the profile of any commenter participating in said activities.

Disqus Tips To upload an avatar photo, first complete your Disqus profile. | View the list of supported HTML tags you can use to style comments. | Please read our commenting policy.