testing-guide

# Skill: Testing Guide Write or review xUnit tests for a Syncfusion Toolkit for .NET MAUI control change. ## When to Use This Skill - ✅ Writing new tests after a bug fix or feature - ✅ Reviewing whether existing tests cover a change adequately - ✅ Called from another agent to handle the test-writing step --- ## Inputs Required The caller (agent or user) must provide: | Input | Description | |-------|-------------| | **Control area** | e.g., `Chart`, `Calendar`, `Popup` | | **What changed** | A summary of the fix or feature that was implemented | | **Affected files** | Source files that were modified | --- ## Step 1: Locate the Test File ``` maui/tests/Syncfusion.Maui.Toolkit.UnitTest/{ControlArea}/ ``` ```bash find maui/tests/Syncfusion.Maui.Toolkit.UnitTest/{ControlArea}/ -name "*.cs" | head -20 ``` If no test file exists for the control area, create one following the naming pattern of adjacent test files. --- ## Step 2: What to Test Add tests for **all scenarios that are possible** given the control's design: | Change Type | What to Cover | |-------------|--------------| | Bug fix | Reproduce the bug — must fail without fix, pass with fix | | Feature | Validate new behavior end-to-end | | Edge cases | Boundary values, null inputs where nullable is allowed, default state, repeated calls | **Naming convention**: `MethodOrProperty_Scenario_ExpectedBehavior` ```csharp [Fact] public void SomeProperty_WhenSetToValue_ShouldUpdateBehavior() { // Arrange var control = new SomeControl(); // Act control.SomeProperty = expectedValue; // Assert Assert.Equal(expectedValue, control.InternalState); } ``` > Use **hard tabs** for indentation. Do NOT use the `private` keyword. --- ## Step 3: What NOT to Test (Impossible Scenarios) Do NOT write tests for scenarios that are architecturally impossible. A scenario is **impossible** if: | Reason | Example | |--------|---------| | Type system prevents the state | Testing `null` on a non-nullable `required` property | | Constructor guarantees initialization | Testing "uninitialized" state on a property set in the constructor | | Code path can never be reached | A branch guarded by a condition always true/false by design | | Platform API unavailable in unit test context | Testing a renderer or native handler requiring a live platform runtime | | Contradicts control invariants | Setting an index out of range when the setter clamps to valid range | --- ## Step 4: Document Skipped Scenarios For each impossible scenario, add a row to `## Skipped Tests` in the caller's state file (or report directly to the user if invoked standalone): ```markdown ## Skipped Tests | Scenario | Reason Impossible | |----------|-------------------| | `Items_WhenNull_ShouldNotThrow` | `Items` is initialized in constructor; can never be null | | `OnPlatformRenderer_WhenDetached` | Requires native platform runtime; not testable in xUnit | ``` --- ## Step 5: Build and Run Tests ```bash # Build first to catch compile errors dotnet build ./Syncfusion.Maui.Toolkit.sln # Run all unit tests dotnet test maui/tests/Syncfusion.Maui.Toolkit.UnitTest/ # Run tests filtered to this control area dotnet test maui/tests/Syncfusion.Maui.Toolkit.UnitTest/ --filter "FullyQualifiedName~{ControlArea}" ``` Report results to the caller or user: tests passed ✅, failed ❌, or skipped with reason.