CLI run/debug commands should detect the type of device

[blagoev]

When run/debug command is started it should detect the type of device and make the device Id optional in cases when only one device and one emulator is found.

--emulator and --device should detect the devices connected and ask for device id only when a decision can not be made.

[dtopuzov]

In Android emulator and device are both devices, so with one emulator and one device you also can not make a decision.
I think we should work in the same way Android Studio works, otherwise we can confuse Android developers.

[blagoev]

First lets say that there is a way to make a distinction between android device and android emulator.

Lets paraphrase this issue to be more clear.
The request is to handle tns commands as follows on the specific case when there one android emulator and one android device connected.

• "tns debug android" should fail with asking the user to specify device id
• "tns debug --emulator" should start the app on the emulator
• "tns debug --device" should start the app on the device with no device Id parameter required

@dtopuzov Android Studio has one button to debug an application (not separate buttons for emulators and devices), thus showing a combined UI with all emulators and devices connected. Android Studio is not the best example in our case.

The better example is adb where:
"adb -e" command which given only one emulator, regardless how many devices there are, will start the next command on that emulator
"adb -d" command which give only one device is connected, regardless how many emulators there are, will start the command on that said device.

The problem manifests itself mostly in VS code where we have a UI for specifying emulator and device separately, ie "Launch on Android Device" and "Launch on Android Emulator". Currently there is a way to specify the deviceId with tnsArgs in launch.config json by manually editing the file. But having that the developer has one device and one emulator most of the time we should improve the experience.
In short there is no need for me to specify an emulator since I already selected that from the debug UI.

Having said this it is worth mentioning this is a usability improvement feature which will greatly ease the developer.

Hope this clears the confusion a bit.

[blagoev]

After short discussion we decided to close this. The --emulator option will be depreciated soon and visual studio code {N} extension will have "Launch on Android" option only. This will start the app on the SINGLE available emulator or device or will fail if multiple devices are present. There is always an option to specify the target device using tnsArgs in launch.json file when multiple devices are connected. This will be on par with how CLI handles these cases.

closing this issue.