Attempt to fix tests when Dispatch is unavailable

Sources/TokamakTestRenderer/TestFiberRenderer.swift

@@ -177,6 +177,7 @@ public struct TestFiberRenderer: FiberRenderer {
     }
   }
 
+  #if canImport(Dispatch)
   public final class WorkItemBox {
     public var workItem: DispatchWorkItem?
   }
@@ -191,4 +192,9 @@ public struct TestFiberRenderer: FiberRenderer {
     DispatchQueue.global(qos: .default).async(execute: workItem)
     self.workItem.workItem = workItem
   }
+  #else
+  public func schedule(_ action: @escaping () -> ()) {
+    action()
+  }
+  #endif
 }

Tests/TokamakReconcilerTests/TestViewProxy.swift

@@ -20,7 +20,9 @@ import TokamakCore
 
 import TokamakTestRenderer
 
+#if canImport(Dispatch)
 import Dispatch
+#endif
 
 @dynamicMemberLookup
 struct TestViewProxy<V: View> {
@@ -81,7 +83,10 @@ extension FiberReconciler where Renderer == TestFiberRenderer {
 
   /// Wait for the scheduled action to complete.
   func turnRunLoop() {
+    #if canImport(Dispatch)
     renderer.workItem.workItem?.wait()
     renderer.workItem.workItem = nil
+    #else
+    #endif
   }
 }

Tests/TokamakReconcilerTests/VisitorTests.swift

@@ -221,6 +221,9 @@ final class VisitorTests: XCTestCase {
     )
     XCTAssertEqual(stateObjectButton.label, Text("0"))
     stateObjectButton.action?()
+    #if !canImport(Dispatch)
+    stateObjectButton.action?()
+    #endif
     reconciler.turnRunLoop()
     XCTAssertEqual(stateObjectButton.label, Text("5"))