If you’re not a big Android person, you might not know about ADB, the “Android Debug Bridge”. ADB is a powerful tool provided as part of the Android SDK by Google, that allows running all sorts of interesting commands on a connected emulator or device. One of these commands is adb shell, which gives you shell access to the device filesystem (including root access on emulators or rooted devices). adb shell is the perfect tool for solving many problems.
Appium did not allow running of arbitrary ADB commands. This is because Appium was designed to run in a remote environment, possibly sharing an OS with other services or Appium servers, and potentially many connected Android devices. It would be a huge security hole to give any Appium client the full power of ADB in this context. Recently, the Appium team decided to unlock this functionality behind a special server flag, so that someone running an Appium server could intentionally open up this security hole. This is achieved using –relaxed-security flag. So you can now start up Appium like this to run arbitrary ADB commands,
With Appium running in this mode, you have access to a new “mobile:” command called “mobile: shell“. The Appium “mobile:” commands are special commands that can be accessed using executeScript (at least until client libraries make a nicer interface for taking advantage of them). Here’s how a call to “mobile: shell” looks in Java:
driver.executeScript(“mobile: shell”, arg);
arg needs to be a JSONifiable object with two keys:
- command: a String, the command to be run under adb shell.
- args: an array of Strings, the arguments passed to the shell command.
For example, let’s say we want to clear out the pictures on the SD card, and that on our device, these are located at /mnt/sdcard/Pictures. If we were running ADB on our own without Appium, we’d accomplish our goal by running:
adb shell rm -rf /mnt/sdcard/Pictures/*.*
To translate this to Appium’s “mobile: shell” command, we simply strip off adb shell from the beginning, and we are left with rm -rf /mnt/sdcard/Pictures/*.*
The first word here is the “command”, and the rest constitute the “args”. So we can construct our object as follows:
List removePicsArgs = Arrays.asList(“-rf”, “/mnt/sdcard/Pictures/.”);
Map removePicsCmd = ImmutableMap.of(“command”, “rm”, “args”, removePicsArgs);
driver.executeScript(“mobile: shell”, removePicsCmd);
We can also retrieve the result of the ADB call, for example if we wish to verify that the directory is now indeed empty:
List lsArgs = Arrays.asList(“/mnt/sdcard/Pictures/.”);
Map lsCmd = ImmutableMap.of(“command”, “ls”,”args”, lsArgs);
String lsOutput = (String) driver.executeScript(“mobile: shell”, lsCmd);
The output of our command is returned to us as a String which we can do whatever we want with, including making assertions on it.
In this article, I hope you got the power of ADB through a few simple file system commands. You can actually do many more useful things than delete files with ADB, so go out there and have fun with it in your automation flow.
Reference: Appium Pro
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