test(ios): exercise ScreenController eval

apps/ios/Tests/ScreenControllerTests.swift

@@ -19,10 +19,27 @@ import WebKit
 
     @Test @MainActor func webModeRejectsInvalidURLStrings() {
         let screen = ScreenController()
-        screen.navigate(to: "   \n")
+        screen.navigate(to: "about:blank")
         screen.setMode(.web)
 
         #expect(screen.mode == .web)
     }
-}
 
+    @Test @MainActor func evalExecutesJavaScript() async throws {
+        let screen = ScreenController()
+        let deadline = ContinuousClock().now.advanced(by: .seconds(3))
+
+        while true {
+            do {
+                let result = try await screen.eval(javaScript: "1+1")
+                #expect(result == "2")
+                return
+            } catch {
+                if ContinuousClock().now >= deadline {
+                    throw error
+                }
+                try? await Task.sleep(nanoseconds: 100_000_000)
+            }
+        }
+    }
+}