Step-by-Step Guide: Mocking Dependencies Using VBMock

VBMock is a specialized, classic mocking framework tailored specifically for legacy Visual Basic (VB6) environments, which historically used tools like VBUnit.

When discussing “boosting VB.NET test coverage fast with VBMock,” it usually indicates modernizing a legacy VB6 system by migrating it to VB.NET, or using VBMock as inspiration to structure tests during a transition. True VB.NET codebases leverage modern .NET ecosystem tools for fast coverage gains. The Strategy: Fast Test Coverage for VB.NET

To scale your VB.NET application’s test coverage quickly, you must combine modern isolation frameworks with automation tools. 1. Replace VBMock with Modern .NET Frameworks

VBMock does not natively support modern VB.NET paradigms like generics, lambdas, or async/await. To build tests quickly, transition to modern mocking tools:

Moq: The most popular open-source framework for mocking interfaces and virtual methods directly in VB.NET.

NSubstitute: Known for its simple, clean syntax that fits well with VB.NET’s natural-language readable style.

Telerik JustMock / Typemock Isolator: Commercial tools capable of mocking non-virtual methods, shared modules, and sealed classes without rewriting old code. 2. Generate and Track Coverage Automations

Do not waste time manually guessing where your test gaps are. Use automated collection tools:

Coverlet: A cross-platform code coverage framework for .NET that runs seamlessly during dotnet test.

Fine Code Coverage: A free Visual Studio extension that highlights exactly which lines of VB.NET code are tested (green) or missed (red) in real-time.

ReportGenerator: Converts raw XML output from tests into highly visual HTML dashboards detailing gaps in your business logic. Modern VB.NET Mocking Example

Here is how you quickly mock dependencies in VB.NET using Moq to safely isolate a class and achieve 100% test coverage on its logic without touching a live database:

Imports Microsoft.VisualStudio.TestTools.UnitTesting Imports Moq Public Class CustomerServiceTests Public Sub GetWelcomeMessage_ValidUser_ReturnsCorrectGreeting() ‘ 1. Arrange: Create a mock of the database dependency Dim mockRepo = New Mock(Of ICustomerRepository)() ’ Setup the mock to return a fake customer object instantly mockRepo.Setup(Function(repo) repo.GetCustomerName(123)).Returns(“Alice”) ‘ Inject the mock into the service Dim service = New CustomerService(mockRepo.Object) ’ 2. Act: Run the target logic Dim result As String = service.GetWelcomeMessage(123) ‘ 3. Assert: Verify the outcome Assert.AreEqual(“Hello, Alice!”, result) End Class End Class Use code with caution. Best Practices for Quick Wins

Code Coverage Tool for C# and VB.NET with dotTEST – Parasoft