feat(companion): type text with replace semantics

companion/Sources/TextInput.swift

@@ -0,0 +1,43 @@
+import XCTest
+
+// Types unicode text into the focused element through the public typeText API,
+// avoiding the pasteboard entirely. With replace enabled, the current value
+// length is consumed first by prepending that many delete keys so the whole
+// replacement happens in one typeText call.
+enum TextInput {
+    static func type(text: String, replace: Bool, bundleIdentifier: String) throws {
+        let application = XCUIApplication(bundleIdentifier: bundleIdentifier)
+        let focused = focusedElement(in: application)
+
+        var payload = text
+        if replace {
+            let currentLength = currentValueLength(of: focused)
+            if currentLength > 0 {
+                let deletes = String(repeating: XCUIKeyboardKey.delete.rawValue, count: currentLength)
+                payload = deletes + text
+            }
+        }
+
+        if let focused = focused {
+            focused.typeText(payload)
+        } else {
+            application.typeText(payload)
+        }
+    }
+
+    private static func focusedElement(in application: XCUIApplication) -> XCUIElement? {
+        let predicate = NSPredicate(format: "hasKeyboardFocus == true")
+        let matches = application.descendants(matching: .any).matching(predicate)
+        if matches.count > 0 {
+            return matches.element(boundBy: 0)
+        }
+        return nil
+    }
+
+    private static func currentValueLength(of element: XCUIElement?) -> Int {
+        guard let element = element, let value = element.value as? String else {
+            return 0
+        }
+        return value.count
+    }
+}