KeyTester

KeyTester allows you to check whether your keyboard is working or not, it also gives you the correspondent KeyEvent constant that developers can use when working with the following Java methods:
Activity.dispatchKeyEvent
Activity.dispatchKeyShortcutEvent
Activity.onKeyDown
Activity.onKeyLongPress
Activity.onKeyMultiple
Activity.onKeyShortcut
Activity.onKeyUp
any other method that deals with KeyEvents

Some buttons such as Home, Recent Apps (Multitasking) and Power won't be detected because the system needs them to be always available and working (e.g., when an app freezes and the user wants to terminate it), so it won't let any app intercept them.

This app is open source, you can find its source code on GitHub: https://github.com/a13ssandr0/KeyTester