docs: Document unlock better (#734)

README.md

@@ -143,11 +143,11 @@ appium:noSign | Set it to `true` in order to skip application signing. By defaul
 
 Capability Name | Description
 --- | ---
-appium:skipUnlock | Whether to skip the check for lock screen presence (`true`). The default driver behaviour is to verify the presence of the screen lock (e.g. 'false' value of the capability) before starting the test and to unlock that (which sometimes might be unstable). Note, that this operation takes some time, so it is highly recommended to set this capability to `true` and disable screen locking on device(s) under test.
-appium:unlockType | Set one of the possible types of Android lock screens to unlock. Read the [Unlock tutorial](https://github.com/appium/appium-android-driver/blob/master/docs/UNLOCK.md) for more details.
-appium:unlockKey | Allows to set an unlock key. Read the [Unlock tutorial](https://github.com/appium/appium-android-driver/blob/master/docs/UNLOCK.md) for more details.
-appium:unlockStrategy | Either 'locksettings' (default) or 'uiautomator'. Setting it to 'uiautomator' will enforce the driver to avoid using special ADB shortcuts in order to speed up the unlock procedure.
-appium:unlockSuccessTimeout | Maximum number of milliseconds to wait until the device is unlocked. `2000` ms by default
+appium:skipUnlock | Whether to skip the check for lock screen presence (`true`). The default driver behaviour is to verify the presence of the screen lock (e.g. 'false' value of the capability) before starting the test and to unlock that (which sometimes might be unstable). Note, that this operation takes some time, so it is highly recommended to set this capability to `true` and disable screen locking on device(s) under test. Read the [Unlock tutorial](./docs/unlock/main.md) for more details.
+appium:unlockType | Set one of the possible types of Android lock screens to unlock. Read the [Unlock tutorial](./docs/unlock/main.md) for more details.
+appium:unlockKey | Allows to set an unlock key. Read the [Unlock tutorial](./docs/unlock/main.md) for more details.
+appium:unlockStrategy | Either 'locksettings' (default) or 'uiautomator'. Read the [Unlock tutorial](./docs/unlock/main.md) for more details.
+appium:unlockSuccessTimeout | Maximum number of milliseconds to wait until the device is unlocked. `2000` ms by default. Read the [Unlock tutorial](./docs/unlock/main.md) for more details.
 
 ### MJPEG
 

docs/unlock/main.md

@@ -0,0 +1,95 @@
+# Unlock
+
+UiAutomator2 driver allows to deal with the Android lock screen using various APIs.
+This article describes the available APIs and their options.
+
+## Unlock On Session Startup
+
+UiAutomator2 provides the following [capabilities](../../README.md#device-locking) to deal
+with the system lock screen:
+
+- appium:unlockStrategy
+- appium:unlockSuccessTimeout
+- appium:skipUnlock
+- appium:unlockType
+- appium:unlockKey
+
+These capabilities could be used to unlock the device under test during the driver session initialization
+as well as deal with different lock screen types.
+
+### appium:unlockStrategy
+
+Either `locksettings` (default since Android 8/API level 26) or `uiautomator` (legacy).
+
+The `locksettings` strategy uses `adb shell locksettings` CLI to deal with different
+types of device lock screens. It is fast, reliable, but has one downside: the actual
+pin, pattern or password must be temporarily removed in order to unlock the device and restored afterwards.
+
+Setting the strategy to `uiautomator` will enforce the driver to use UiAutomator framework in order
+to interact with the device's lock screen for various unlock types. It might be slower and less stable in comparison
+to the `locksettings` strategy, although there is no other alternative if tests are being executed on an older Android version
+or the application under test requires the device to constantly maintain display lock settings.
+
+### appium:unlockSuccessTimeout
+
+Maximum number of milliseconds to wait until the device is unlocked. `2000` ms by default
+
+### appium:skipUnlock
+
+The `appium:skipUnlock` capability is enabled by default and makes the driver to detect and handle the lock screen
+upon session startup _if it is present_. If the lock screen cannot be detected upon session startup then nothing will be
+done. By default, it is assumed the device has a "simple" lock screen, which could be removed by waking up the device.
+In case the device has a different type of the lock screen configured in its settings then the information about it
+must be provided in the below capability values.
+
+### appium:unlockType and appium:unlockKey
+
+This capability supports the following possible values:
+
+#### pin
+
+Assumes the the device is protected with a PIN code. Expects the `appium:unlockKey` to contain a valid pin consisting
+of digits in range 0-9, for example `1111`.
+
+#### pinWithKeyEvent
+
+Same as [pin](#pin), but uses ADB instead of UiAutomator framework to enter the actual pin value.
+
+#### password
+
+Assumes the the device is protected with a password. Expects the `appium:unlockKey` to contain a valid password consisting
+of latin characters, for example `abcd1234`.
+
+#### pattern
+
+Assumes the the device is protected with a secret pattern. Check the example below for more details on the `appium:unlockKey`
+value for this particular unlock type.
+
+##### Example
+
+Lets say you have a device that is locked with a pattern similar to the one on the image below,
+and you want to run a test over that device.
+
+<img src="./screen1.png" />
+
+We treat the pattern pins similarly to numbers on a digital phone dial. So, in this case the *unlockKey* is `729854163`
+
+<img src="./screen2.png" />
+
+and capabilities are:
+
+```json
+{
+  "appium:unlockType": "pattern",
+  "appium:unlockKey": "729854163"
+}
+```
+
+## Mid-Session Unlock
+
+There is also a possibility to interact with the device's lock screen while the test session is running.
+Use the following mobile extensions for this purpose:
+
+- [mobile: lock](../../README.md#mobile-lock)
+- [mobile: unlock](../../README.md#mobile-unlock)
+- [mobile: isLocked](../../README.md#mobile-islocked)