[WIFI] Update instructions for running tests

The easiest way to run tests is simply run

```

frameworks/base/wifi/tests/runtests.sh

atest android.net.wifi

```

`runtests.sh` will build the test project and all of its dependencies and push the APK to the

connected device. It will then run the tests on the device.

To pick up changes in framework/base, you will need to:

1. rebuild the framework library 'make -j32'

2. sync over the updated library to the device 'adb sync'

2. adb reboot

3. adb remount

See below for a few example of options to limit which tests are run.

See the

[AndroidJUnitRunner Documentation](https://developer.android.com/reference/android/support/test/runner/AndroidJUnitRunner.html)

for more details on the supported options.

```

runtests.sh -e package android.net.wifi

runtests.sh -e class android.net.wifi.WifiScannerTest

```

If you manually build and push the test APK to the device you can run tests using

```

adb shell am instrument -w 'android.net.wifi.test/androidx.test.runner.AndroidJUnitRunner'

```

## Adding Tests

Tests can be added by adding classes to the src directory. JUnit4 style test cases can

be written by simply annotating test methods with `org.junit.Test`.

#!/usr/bin/env bash

if [ -z $ANDROID_BUILD_TOP ]; then

  echo "You need to source and lunch before you can use this script"

  exit 1

fi

echo "Running tests"

set -e # fail early

echo "+ mmma -j32 $ANDROID_BUILD_TOP/frameworks/base/wifi/tests"

# NOTE Don't actually run the command above since this shell doesn't inherit functions from the

#      caller.

$ANDROID_BUILD_TOP/build/soong/soong_ui.bash --make-mode MODULES-IN-frameworks-base-wifi-tests

set -x # print commands

adb wait-for-device

TARGET_ARCH=$($ANDROID_BUILD_TOP/build/soong/soong_ui.bash --dumpvar-mode TARGET_ARCH)

adb install -r -g "$OUT/testcases/FrameworksWifiApiTests/$TARGET_ARCH/FrameworksWifiApiTests.apk"

adb shell am instrument --no-hidden-api-checks -w "$@" \

  'android.net.wifi.test/androidx.test.runner.AndroidJUnitRunner'