[Android][CTS]./cts-tradefed Unable to find aapt in path.

碰到一個問題：

~/tools/cts/android-cts-8.1_r6-linux_x86-arm/android-cts/tools$ ./cts-tradefed 
Unable to find aapt in path.

然後去 install，未成功:

$ sudo apt-get install aapt
Reading package lists... Done
Building dependency tree       
Reading state information... Done
E: Unable to locate package aapt

最後解決辦法：去out 目錄下將out/host/linux-x86/bin/aapt放到某個目錄下(如：~/tools/bin/aapt)，將該目錄（如：~/tools/bin/aapt） 添加到 PATH 中去。

export PATH=$PATH:~/tools/bin/

最後就可以運行了

./cts-tradefed 

接下來就可以測試CTS了：

run cts -c class_name -m method_name 

eg. 
run cts -c com.android.cts.aadb.TestDeviceFuncTest -m testSyncFiles_extStorageVariable --skip-preconditions 
run cts -c com.android.cts.aadb.TestDeviceFuncTest -m testSyncFiles_normal --skip-preconditions 

end