bUnit Test Migration Skill (Beta → 2.x)

This skill provides guidance for migrating test files from the deprecated bUnit 1.0.0-beta-10 API to bUnit 2.5.3 stable API. Use this when you encounter test files using the old TestComponentBase, <Fixture>, or <SnapshotTest> patterns.

When to Apply

Apply this skill when a .razor test file contains any of these patterns:

•@inherits TestComponentBase
•<Fixture Test="...">
•<ComponentUnderTest>
•<SnapshotTest>
•void MethodName(Fixture fixture)

Transformation Rules

1. Change Inheritance

diff

- @inherits TestComponentBase
+ @inherits BunitContext

2. Remove Wrapper Elements

Remove these XML elements entirely (keep only the component inside):

diff

- <Fixture Test="TestName">
-     <ComponentUnderTest>
          <MyComponent Parameter="value" />
-     </ComponentUnderTest>
- </Fixture>

3. Convert Test Methods

diff

- void TestMethodName(Fixture fixture)
+ [Fact]
+ public void ComponentName_Scenario_ExpectedResult()

4. Replace Component Access

diff

- var cut = fixture.GetComponentUnderTest();
+ var cut = Render(@<MyComponent Parameter="value" />);

5. Convert Snapshot Tests

diff

- <SnapshotTest Description="renders correctly">
-     <TestInput>
-         <MyComponent />
-     </TestInput>
-     <ExpectedOutput>
-         <div>expected html</div>
-     </ExpectedOutput>
- </SnapshotTest>
+ [Fact]
+ public void MyComponent_Default_RendersCorrectly()
+ {
+     var cut = Render(@<MyComponent />);
+     cut.MarkupMatches(@<div>expected html</div>);
+ }

Complete Example

Before

razor

@inherits TestComponentBase

<Fixture Test="ShouldClickButton">
    <ComponentUnderTest>
        <Button OnClick="OnClick">Click me</Button>
    </ComponentUnderTest>
</Fixture>

@code {
    int ClickCount = 0;

    void ShouldClickButton(Fixture fixture)
    {
        var cut = fixture.GetComponentUnderTest();

        cut.Find("button").Click();

        ClickCount.ShouldBe(1);
    }

    void OnClick() => ClickCount++;
}

After

razor

@inherits BunitContext

@code {
    int ClickCount = 0;

    [Fact]
    public void Button_Click_IncrementsCounter()
    {
        var cut = Render(@<Button OnClick="OnClick">Click me</Button>);

        cut.Find("button").Click();

        ClickCount.ShouldBe(1);
    }

    void OnClick() => ClickCount++;
}

Test Naming Convention

Pattern: ComponentName_Scenario_ExpectedResult

Component	Scenario	Result	Test Name
Button	Click	InvokesHandler	`Button_Click_InvokesHandler`
DataList	EmptySource	ShowsEmptyTemplate	`DataList_EmptySource_ShowsEmptyTemplate`
GridView	WithData	RendersRows	`GridView_WithData_RendersRows`

Special Patterns

Multiple Tests in One File

Each <Fixture> block becomes a separate [Fact] method:

razor

@inherits BunitContext

@code {
    [Fact]
    public void Component_FirstScenario_ExpectedResult() { ... }

    [Fact]
    public void Component_SecondScenario_ExpectedResult() { ... }
}

Tests with Services

razor

@code {
    [Fact]
    public void Component_WithService_Works()
    {
        Services.AddSingleton<IMyService>(new FakeService());

        var cut = Render(@<MyComponent />);
    }
}

Authentication Tests

razor

@code {
    [Fact]
    public void SecureComponent_AuthenticatedUser_ShowsContent()
    {
        var authContext = this.AddTestAuthorization();
        authContext.SetAuthorized("TestUser");
        authContext.SetRoles("Admin");

        var cut = Render(@<SecureComponent />);
    }
}

Tests Requiring New TestContext

For tests that need isolated context (e.g., multiple renders):

razor

@code {
    [Fact]
    public void Component_MultipleRenders_WorksCorrectly()
    {
        using var ctx = new Bunit.TestContext();

        var cut1 = ctx.Render(@<MyComponent Value="1" />);
        var cut2 = ctx.Render(@<MyComponent Value="2" />);

        cut1.Find("span").TextContent.ShouldBe("1");
        cut2.Find("span").TextContent.ShouldBe("2");
    }
}

Quick Reference Table

Old Pattern	New Pattern
`@inherits TestComponentBase`	`@inherits BunitContext`
`<Fixture Test="Name">`	Remove
`<ComponentUnderTest>`	Remove
`<SnapshotTest>`	`[Fact]` method with `MarkupMatches()`
`void Name(Fixture fixture)`	`[Fact] public void Name()`
`fixture.GetComponentUnderTest()`	`Render(@<Component />)`
`fixture.GetComponentUnderTest<T>()`	`Render<T>(@<Component />)`

Verification

After migrating a file, verify with:

powershell

# Build check
dotnet build src/BlazorWebFormsComponents.Test --no-restore

# List discovered tests
dotnet test src/BlazorWebFormsComponents.Test --list-tests --filter "FullyQualifiedName~ComponentName"

# Run tests
dotnet test src/BlazorWebFormsComponents.Test --filter "FullyQualifiedName~ComponentName"

Common Errors

Error	Cause	Fix
`CS0246: TestComponentBase not found`	Old inheritance	Change to `@inherits BunitContext`
`CS0103: Fixture does not exist`	Old wrapper element	Remove `<Fixture>` tags
`No tests discovered`	Missing `[Fact]` attribute	Add `[Fact]` to test methods
`Method must be public`	Private test method	Add `public` modifier