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----
-name: add_dual_test_case
-description: OpenSwiftUI DualTests Rules
----
-
-# OpenSwiftUI DualTests Rules
-
-This file documents precise rules and templates for writing Tests and DualTests used across the OpenSwiftUI repository. Follow these rules exactly when generating new test cases.
-
-## General principles
-- Use the `swift-testing` framework and the `#expect` macro for all assertions.
-- Do NOT use XCTest unless explicitly required for compatibility.
-- Keep test function bodies free of comments.
-- Use descriptive test function names (do not prefix with `test`).
-- Use `@Test` for each test function.
-- Group related tests with `// MARK: -`.
-- Keep tests small and focused.
-- Use `package` / access-level rules only inside implementation files — tests import the target.
-
-## File layout and naming
-- Test filenames should end with `Tests.swift`.
-- Put project-only tests in `Tests/*Tests`.
-- Put dual tests that compare against SwiftUI in `Tests/*SymbolDualTests`.
-- Use `struct <FeatureName>Tests { ... }` to group tests.
-
-## Test file headers and conditions
-
-Project-only tests (call OpenSwiftUI APIs):
-- Use compile condition matching the implementation (example: `#if os(iOS) && canImport(QuartzCore)`).
-- Required imports:
-  - `import Testing`
-  - `@_spi(ForOpenSwiftUIOnly) import OpenSwiftUICore` (if testing internal SPI)
-  - platform framework imports (e.g., `import QuartzCore`)
-
-DualTests (call into SwiftUI symbol via stub):
-- Use a condition that ensures SwiftUI is available and matches the reference SDK:
-  - Example: `#if os(iOS) && canImport(SwiftUI, _underlyingVersion: 6.5.4)`
-- Required imports:
-  - `import QuartzCore`
-  - `import Testing`
-- Provide a `@_silgen_name` initializer (or function) declaration on the type to call the SwiftUI symbol:
-  - Example:
-    extension CAFrameRateRange {
-        @_silgen_name("OpenSwiftUITestStub_CAFrameRateRangeInitInterval")
-        init(swiftUI_interval: Double)
-    }
-- Provide a C stub that publishes the SwiftUI symbol name for the test bundle (placed in SymbolDualTestsSupport target). The C file must define the same symbol name used in `@_silgen_name`.
-
-## Test implementation rules
-- Use `@Test(arguments: [...])` to run parameterized cases when appropriate.
-- Argument arrays must be typed where necessary (e.g., `as [(Double, CAFrameRateRange)]`).
-- In each `@Test` function:
-  - Instantiate or call the API under test.
-  - Use `#expect(...)` for every assertion.
-  - Do not include comments inside the test function body.
-- Use exact equality checks where types are Equatable (e.g., `#expect(range == expected)`).
-
-## Small templates
-
-Project test template:
-```swift
-// ... file header and #if condition ...
-import Testing
-@_spi(ForOpenSwiftUIOnly) import OpenSwiftUICore
-import QuartzCore
-
-struct <FeatureName>Tests {
-    @Test(arguments: [
-        // example tuples
-    ] as [(/* types */)])
-    func <scenario>(/* params */) {
-        let result = /* call OpenSwiftUI API */
-        #expect(result == expected)
-    }
-}
-```
-
-Dual test template:
-```swift
-// ... file header and #if condition ...
-import QuartzCore
-import Testing
-
-extension <TypeUnderTest> {
-    @_silgen_name("<C stub symbol name>")
-    init(swiftUI_<param>: /* type */)
-}
-
-struct <FeatureName>DualTests {
-    @Test(arguments: [
-        // example tuples
-    ] as [(/* types */)])
-    func <scenario>(/* params */) {
-        let result = <TypeUnderTest>(swiftUI_<param>: input)
-        #expect(result == expected)
-    }
-}
-```
-
-C stub template (SymbolDualTestsSupport target):
-```c
-// Provide a C stub that resolves to the SwiftUI initializer/function
-// Use the same symbol name used in @_silgen_name in the DualTest
-#include "OpenSwiftUIBase.h"
-
-#if OPENSWIFTUI_TARGET_OS_IOS
-
-#import <SymbolLocator.h>
-
-DEFINE_SL_STUB_SLF(<C stub symbol name>, SwiftUICore, <mangled SwiftUI symbol>);
-
-#endif
-```
-
-## Examples and important notes
-- Do not include test-comments in function bodies.
-- Keep parameterized arguments typed explicitly when the compiler cannot infer them.
-- Match the platform compile conditions to the implementation file being tested.
-- When comparing framework-provided types (e.g., `CAFrameRateRange`) rely on their Equatable conformance using `==`.
-- Ensure the C stub symbol name and the `@_silgen_name` string are identical.
-
-## Checklist before committing test code
-- [ ] Uses `Testing` and `#expect` exclusively.
-- [ ] No comments inside `@Test` function bodies.
-- [ ] Proper compile-time conditions are present.
-- [ ] DualTests have matching C stubs in the SymbolDualTestsSupport target.
-- [ ] Test file and struct names follow repository conventions.