Channels ▼


Distributed Unit Testing

Source Code Accompanies This Article. Download It Now.

Developing Automated Tests with PNUnit

Figure 1 shows the basic structure and main components of the PNUnit system. Launcher is the program responsible for launching test suites on test machines. It is called by a test configuration file as an argument, reads the file, and sends instructions to the testing machines. It then gathers test results and prints them on the screen. The test configuration (testconf) file is written in XML and contains a definition of the test scenario being created. It defines the appropriate assemblies, specifies where they have to run, and identifies the data to execute. Figure 2, a typical testconf file, contains at least one parallel test section (test group). Each test group runs sequentially. Several tests are defined inside the test group and identified with TestConf labels. Each test inside the group runs in parallel, so each test group defines a parallel scenario.

Figure 1: PNUnit high-level structure.

[Click image to view at full size]

Figure 2: Test script.

The TestConf section tells Launcher in which assembly the test resides, which method to invoke, and where the machine is to launch it. Launcher uses this information to communicate with the Agent. To handle communications, Launcher creates a Runner for each test defined in a test group. The Runner is the component that calls the Agent methods. More importantly, Runner handles synchronization via the IPNUnitServices interface that it exports to the tests. Runner also gathers test results and informs Launcher about them.

Section Field
Name Test name you want displayed on the results screen.
Assembly .NET Assembly in which the test resides.
TestToRun Method name that defines the test to be run.
Machine Machine where you want the test executed.
TestParams Test-specific parameters.

Table 1: TestConf members.

Agents are located on test machines. Each test machine needs to have at least one Agent waiting to run tests. Agent is a small .NET application that, once started, registers a remote interface called IPNUnitAgent. This is the interface that Runner uses to launch the tests. PNUnitAgent is the actual component inside agents that handles the various processes.

Each time PNUnit receives a call in the IPNUnitAgent::RunTest method (meaning that a new test needs to be launched), it creates a new instance of PNUnitTestRunner. In NUnit parlance, PNUnitTestRunner is a real test runner. It creates a TestDomain instance, runs the test specified by the remote Launcher, collects the results, and notifies the remote Runner. Each test resides on regular assemblies, just as if they were normal NUnit tests.

Where does the NUnit framework fit in? It is the key layer in which PNUnitTestRunner resides. We take advantage of all of NUnit's functionality to load/run tests and collect results.

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.