Unit Testing Plugins

Unit testing is a critical aspect of software development that ensures individual units of code, such as functions or methods, work as expected in isolation. For developers working with Microsoft Dynamics 365, unit testing is equally crucial to ensure that plugins and custom business logic run smoothly. Dynamics 365 plugins are custom pieces of code that can be executed in response to various events in the system, such as the creation or updating of records. Writing unit tests for these plugins ensures their reliability, efficiency, and ease of maintenance.

In this article, we will explore the significance of unit testing for plugins in Dynamics 365, the tools and frameworks available for writing unit tests, best practices for implementing unit tests, and the steps to follow to get the most out of unit testing your plugins.

What are Plugins in Dynamics 365?

In Microsoft Dynamics 365, plugins are custom business logic that is executed in response to specific events triggered by user actions or system processes. Plugins can be registered to run during a variety of stages in the lifecycle of an entity, such as Pre-validation, Pre-operation, Post-operation, and Asynchronous. These plugins can perform complex business logic, such as data validation, calculations, integration with external systems, or enforcing business rules.

Plugins in Dynamics 365 are typically written in C# and are deployed within the Dynamics 365 platform. They are registered and managed through the Plugin Registration Tool or through Solution Explorer in Visual Studio. The ability to test plugins before deployment is essential for ensuring that the business logic behaves as intended and does not interfere with the rest of the system.

Importance of Unit Testing Plugins

Unit testing helps developers detect issues early in the development cycle. For Dynamics 365 plugins, unit testing plays a crucial role in several areas:

1. Quality Assurance: Unit testing ensures that the plugin functions as expected in isolation. This is particularly important when plugins are part of a larger system where their failure can cause cascading issues.
2. Regression Testing: Plugins may change over time due to new requirements or bug fixes. Unit testing allows developers to make sure that these changes do not break existing functionality.
3. Maintainability: Writing unit tests for plugins makes it easier to maintain the codebase. If any changes are made to the plugin, unit tests act as a safety net to ensure that existing functionality remains intact.
4. Faster Development Cycle: Unit tests enable faster feedback loops, reducing the time spent debugging and fixing issues in production.
5. Compliance and Business Rules: Many Dynamics 365 applications involve strict business rules and compliance requirements. Unit testing ensures these rules are consistently enforced.

Tools and Frameworks for Unit Testing Plugins

Several tools and frameworks are available for unit testing plugins in Dynamics 365. Below are some of the most popular ones:

1. XUnit

XUnit is a popular testing framework for .NET applications. It provides a rich set of features for writing unit tests, including support for assertions, setup, and teardown operations. XUnit is commonly used for writing unit tests for Dynamics 365 plugins.

• Advantages:
  • Works well with other .NET-based libraries.
  • Lightweight and simple to use.
  • Provides support for test parallelization.
• Disadvantages:
  • Lacks built-in support for mocking external systems.

2. MSTest

MSTest is Microsoft’s official testing framework for .NET applications. It is deeply integrated with Visual Studio, and provides comprehensive support for testing plugins in Dynamics 365.

• Advantages:
  • Fully supported by Visual Studio.
  • Supports unit, integration, and functional testing.
  • Built-in assertion library.
• Disadvantages:
  • Can be verbose in its syntax compared to other frameworks.

3. NUnit

NUnit is another widely used unit testing framework for .NET applications. It is highly extensible and provides many features that help with testing Dynamics 365 plugins.

• Advantages:
  • A large collection of assertion methods.
  • Easy integration with .NET projects.
  • Supports parameterized tests.
• Disadvantages:
  • Lacks some features that XUnit and MSTest provide out of the box.

4. Moq (Mocking Framework)

Moq is a popular mocking library for .NET. It helps developers create mock objects for dependencies during unit testing. For Dynamics 365 plugins, which often interact with the platform’s SDK (e.g., IOrganizationService), Moq is essential for simulating real interactions and ensuring that the plugin code is tested in isolation.

• Advantages:
  • Simplifies testing by allowing you to mock services.
  • Integrates seamlessly with XUnit, MSTest, and NUnit.
• Disadvantages:
  • Requires developers to have a basic understanding of mocking techniques.

Writing Unit Tests for Dynamics 365 Plugins

1. Setting Up the Testing Environment

Before you can start writing unit tests for Dynamics 365 plugins, it’s essential to set up a suitable testing environment. Here’s how you can set up the environment:

• Install Visual Studio: You’ll need Visual Studio or another C# development environment for writing the plugin and unit test code.
• Install NuGet Packages: Install necessary packages such as MSTest, XUnit, Moq, and FakeXrmEasy for mocking the Dynamics 365 services.
• Install FakeXrmEasy: FakeXrmEasy is a library that helps simulate Dynamics 365 environment and services (such as IOrganizationService), making unit testing easier without relying on a real Dynamics instance.

Install-Package FakeXrmEasy

2. Writing Unit Tests

The key to effective unit testing is writing small, isolated tests for each unit of functionality. When unit testing Dynamics 365 plugins, you generally need to:

1. Mock External Dependencies: Dynamics 365 plugins often interact with the IOrganizationService to read and write data. To isolate the plugin, you should mock the IOrganizationService and other dependencies (e.g., IPluginExecutionContext).
2. Use FakeXrmEasy: FakeXrmEasy provides a lightweight in-memory Dynamics 365 environment. It allows you to simulate interaction with the IOrganizationService and IPluginExecutionContext without needing a real Dynamics 365 instance.

Here is a simple example of a unit test for a Dynamics 365 plugin:

using FakeXrmEasy;
using Microsoft.Xrm.Sdk;
using Microsoft.VisualStudio.TestTools.UnitTesting;

[TestClass]
public class MyPluginTests
{
    private XrmFakedContext _context;
    private IOrganizationService _service;

    [TestInitialize]
    public void TestInitialize()
    {
        // Set up FakeXrmEasy context and service
        _context = new XrmFakedContext();
        _service = _context.GetOrganizationService();
    }

    [TestMethod]
    public void TestPlugin_WhenEntityIsCreated_ShouldSetFieldValue()
    {
        // Arrange: Create test entity (e.g., Account)
        var account = new Entity("account");
        account["name"] = "Test Account";
        var entityReference = _service.Create(account);

        // Act: Run the plugin (simulate the plugin logic)
        var plugin = new MyPlugin();
        plugin.Execute(new PluginExecutionContext
        {
            MessageName = "Create",
            InputParameters = new ParameterCollection
            {
                { "Target", new EntityReference("account", entityReference) }
            }
        });

        // Assert: Verify that the plugin set the expected value
        var updatedAccount = _service.Retrieve("account", entityReference, new ColumnSet("name"));
        Assert.AreEqual("Test Account", updatedAccount["name"]);
    }
}

In this example, we simulate the creation of an account and verify that the plugin correctly updates a field on the entity. The key here is the use of FakeXrmEasy to simulate the interaction with the Dynamics 365 service, so we don’t have to interact with a live system.

3. Test Different Scenarios

Unit tests should cover various scenarios, including:

• Happy path: The typical, expected flow of events.
• Error handling: Test how the plugin handles errors, such as invalid input or failure to access resources.
• Boundary conditions: Test edge cases where the data or conditions are on the boundary of what is expected.
• Multiple triggers: If your plugin handles multiple events or stages, ensure it behaves correctly for each one.

4. Mocking the Plugin Execution Context

The IPluginExecutionContext is another dependency that is commonly used in plugins. It provides information about the context of the plugin execution, such as the message, entity, and stage. To test plugins, you need to mock this context to simulate the real execution environment.

var context = new Mock<IPluginExecutionContext>();
context.Setup(c => c.InputParameters).Returns(new ParameterCollection());
context.Setup(c => c.MessageName).Returns("Create");

5. Test Deployment and Exception Handling

In addition to normal operation, you should test how your plugin handles exceptions, unexpected inputs, and edge cases. It’s important to ensure that the plugin gracefully handles these scenarios and doesn’t break the system.

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Best Practices for Unit Testing Plugins

Here are some best practices for writing effective unit tests for Dynamics 365 plugins:

1. Isolate Logic: Ensure that the plugin logic is isolated from external dependencies. Use mocking libraries like Moq to simulate interactions with external services.
2. Use Fake Data: Use libraries like FakeXrmEasy to simulate Dynamics 365 entities and services, avoiding the need to interact with a real system.
3. Write Tests for Each Scenario: Unit tests should cover all possible scenarios for the plugin, including error handling, boundary conditions, and valid data paths.
4. Keep Tests Small: Each unit test should focus on one specific behavior of the plugin. This makes tests easier to understand and maintain.
5. Run Tests Frequently: As you develop your plugins, run unit tests frequently to catch issues early.

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