Testing in the IgniteUI Blazor (Lite) repo

Three test projects under tests/, two suites:

How the suites divide the work

The suites overlap on purpose but answer different questions. Integration proves the full pipeline works end-to-end, but can't attribute a failure to a side of the boundary and skips everything excluded in componentsConfig.json. Interop contracts pin the .NET side of the wire protocol at unit speed, per member — including the members integration excludes — and tolerate different implementations through the InteropHarness seam (InteropHarnessRegistry swaps stacks per component).

Unit suite (tests/IgniteUI.Blazor.Tests)

Base classes

• BlazorComponentTestBase — bUnit BunitContext with setup IIgniteUIBlazor service, a recording JS runtime (JSRuntimeMode.Loose; every invocation recorded) and an Interop harness property (an InteropHarness, resolved per component type via InteropFor<TComponent>()). Default base for suites without an interop contract.
• ComponentWithContractTestBase<TComponent> — adds a declarative ComponentContract<TComponent>, protected runners (VerifyMethodContract/VerifyPropContract/VerifyEventContract) that the suite exposes as one-liner [Fact]s, and an inherited Contract_SectionsHaveFacts guard that fails if a non-empty contract section has no runner fact. Exactly one suite per component carries the contract; sync/async method pairs are declared together via the twin overloads.

Running

dotnet test tests/IgniteUI.Blazor.Tests -f net10.0 --nologo --filter "FullyQualifiedName~<Name>Tests"

• Iterate on one TFM (-f net10.0); finish with a full run on all TFMs (drop -f).
• Contract failure stacks carry the violated contract line as the top frame — the test UI navigates to the spec, not the shared runner.

Conventions

• Generally follow one file per component: <Name>Tests.cs holds <Name>Tests. A component's child components may share the parent's file (SelectTests.cs also holds SelectItemTests/SelectGroupTests/SelectHeaderTests; likewise Card, List, Dropdown, NavDrawer, Tabs, Stepper, TileManager, Tree, Rating, Slider) — that's the only permitted multi-class file. Cross-cutting suites (BaseControlTests, SerializationTests, ScriptPropTests, InteropTests) are keyed to a class/behavior, not a component, and keep their own files.
• New facts go into the existing <Name>Tests class; if the class carries a contract, plain bUnit facts sit alongside the contract runners in the same class.
• Shared test helpers live in ElementAssertionExtensions.cs.
• Readable arrange/act/assert in the test beats sharing. A little repetition across suites is fine; extract obvious repeated mechanics if needed, but ensure those are well documented and easy to grasp without breaking the flow of the test itself.
• Skips need a mechanism reason. Bug-tracker or componentsConfig.json listings are not skip reasons. If a member's decode hits a gap in shared infrastructure the change doesn't own, cover it pinning current behavior and write the correct assertion commented out under a // TODO: explaining the gap — ready to uncomment when fixed. A gap in a component under construction is a bug to fix, not to pin — see the two authoring modes in the interop reference.
• Components are partial — the generated src/components/Blazor/<Name>.cs is not the whole class; always check src/componentsBase/WebInputs/<Name>.cs for hand-written extensions before drawing conclusions.
• Formatting: only dotnet format whitespace --folder is safe in this repo — a full dotnet format writes conflict markers into multi-targeted sources.

Integration suite (Playwright + TestBed)

One generic NUnit test per component (ComponentTest, fixture-sourced from the TestBed's component list): it boots the TestBed app (in-memory by default), calls the browser-side renderComponent('<IgbName>'), and asserts getErrors() returns nothing. The real work happens inside the TestBed (Components/Pages/Home.razor): a reflection-driven sweep over the component's public surface —

• TestProps: sets each [Parameter] server-side with generated sample values and compares against the live web component's DOM property in the browser (TestUtil.PropertyValuesAreEqual, client value via stringifyObject).
• TestEvents: dispatches synthetic events against the web component and verifies the bound .NET callbacks fire.
• Method spies (spyOnMethod/checkOnSpy in wwwroot/app.js): invoking the .NET API must call the matching web-component method with the right args/result. Async methods only — the sweep filters to Async and also excludes GetAsync getters; sync variants can't run on the Server-hosted TestBed (no in-process JS runtime), so sync variants, getters, and <Member>Script params have no integration coverage — the unit suite is their only net.

componentsConfig.json (in the TestBed project) gates the sweep per component: ExcludedProps, ExcludedEvents, DependantProps/DependantMethods — each entry usually cites a BUG number or a shape the generic sweep can't model. An excluded member has no integration coverage at all — treat those as higher priority for the unit interop contract, never as members to skip there too.

Running

• One-time: build, then install browsers — pwsh tests/IgniteUI.Blazor.Lite.IntegrationTests/bin/Debug/net<version>/playwright.ps1 install chromium.
• dotnet test tests/IgniteUI.Blazor.Lite.IntegrationTests (or per component from the Test Explorer — fixtures are named by component).
• .runsettings knobs: headless off for local debugging; useInMemoryClient: false to run against your own dotnet run instance of the TestBed.
• Full setup details: [tests/IgniteUI.Blazor.Lite.IntegrationTests/README.md](../../tests/IgniteUI.Blazor.Lite.IntegrationTests/README.md).

Adding coverage for a new component — checklist

1. Unit suite: bUnit facts for rendered attributes/markup; if the component has an interop surface (it sends interop invocations or registers JS-originated event handlers — the reference explains how to identify these per stack), add a ComponentContract per [references/interop-contracts.md](./references/interop-contracts.md). For a brand-new component this works TDD-style: author the contract first from the intended API following the library's conventions; the contract doubles as the API design record (spec mode in the reference).
2. If it is a parent that collects children, or a child that registers with a parent, exercise that membership over the child's lifetime, not just at first render: the children are the collection in order, a disposed child leaves it, all disposed empties it. Keep these facts to membership and asserting resolution that are covered by the interop contract.
3. Integration: the sweep picks the component up automatically; add componentsConfig.json entries only for members the generic sweep genuinely cannot model (cite why), and mirror each exclusion with unit contract coverage.
4. Verify: unit full-suite on all TFMs, plus the component's integration fixture.