feat: launch emulator during run-android

[jayu]

Summary:

This PR resolves #142
TLDR;
Duringreact-native run-android the first of user's emulators will be launched if there is no any running android device/emulator

emulator -list-advs to get a list of emulators
emulator @FIRST_ON_LIST to run the first available emulator

Test Plan:

• Generate a project with React-native >60.0
• install CLI from my fork
• run react-native run-android without launched emulator -> emulator is launching
• run react-native run-android with launched emulator -> nothing new happens
• run react-native run-android with device connected -> nothing new happens
• run react-native run-android without launched emulator, emulator has saved snapshot -> emulator is launching

[thymikee]

Amazing!

[Titozzz]

Something that bothers me, there is no point in declaring a function as async just to await its return, you are just overwrapping stuff as it already returns a promise.

[jayu]

Thanks, @Titozzz :) It was redundant, fixes.

[thymikee]

Last batches of adjustments and I think we're good :)
I wonder if we're able to come up with Genymotion (or other custom emulators I don't know of) support as a followup.

[thymikee]

Still need to test it, but code-wise LGTM 👍 great work @jaysbytes

[thymikee]

cc @satya164 would you like to give it a try? :)

[thymikee]

Just tested locally and fixed a bug I encountered. Also adjusted the wording around errors, warnings and infos a bit. Once CI is happy, this is good to go

[jayu]

@thymikee thanks for the help with shipping of this awesome feature 😀

[a-c-sreedhar-reddy]

Wouldn't it be better if available emulators are shown and asked to select one?

[thymikee]

@a-c-sreedhar-reddy not sure about that. Current behavior matches what we do for iOS. Maybe it's worth to revisit. Can you please create a proposal for that where we can discuss better UX?

[jsjoeio]

Has this feature been included in a recent release?

I didn't see it mentioned in any of the latest release notes

[Shan7anu]

@jsjoeio Yes. It's available in the latest release.

C:\Users\Shan7anu\Desktop\RNProjects\Sample>react-native run-android

info Running jetifier to migrate libraries to AndroidX. You can disable it using "--no-jetifier" flag.
Jetifier found 864 file(s) to forward-jetify. Using 4 workers...
info Starting JS server...
info Launching emulator...
info Successfully launched emulator.
info Installing the app...

[jsjoeio]

Woohoo! Thanks for confirming @Shan7anu!

[ltcompounder]

hello @jayu thanks for adding this feature. unfortunately i seem to be unable to get this to work.

for context, android studio is not running at the time i run npx react-native run-android in terminal.
additional information is that i get this error when i run the above command:
Failed to launch emulator. Reason: The emulator (Pixel_6_API_31) quit before it finished opening. You can try starting the emulator manually from the terminal with: /Library/Android/sdk/emulator/emulator @Pixel_6_API_31.

expected behavior:

1. android studio boots up
2. emulator automatically launches

actual behavior:

1. Build fails with an error com.android.builder.testing.api.DeviceException: No connected devices!

alternatively, i opened up android studio. emulator has not launched yet. i run npx react-native run-android in terminal.
expected behavior:

1. emulator automatically launches

actual behavior:

1. Build fails with an error com.android.builder.testing.api.DeviceException: No connected devices!

workaround:
I resorted to manually running my emulator. only then was i able to run the command npx react-native run-android smoothly.

[cetfu]

hello @jayu thanks for adding this feature. unfortunately i seem to be unable to get this to work.

for context, android studio is not running at the time i run npx react-native run-android in terminal. additional information is that i get this error when i run the above command: Failed to launch emulator. Reason: The emulator (Pixel_6_API_31) quit before it finished opening. You can try starting the emulator manually from the terminal with: /Library/Android/sdk/emulator/emulator @Pixel_6_API_31.

expected behavior:

1. android studio boots up

2. emulator automatically launches

actual behavior:

1. Build fails with an error `com.android.builder.testing.api.DeviceException: No connected devices!`

alternatively, i opened up android studio. emulator has not launched yet. i run npx react-native run-android in terminal. expected behavior:

1. emulator automatically launches

actual behavior:

1. Build fails with an error `com.android.builder.testing.api.DeviceException: No connected devices!`

workaround: I resorted to manually running my emulator. only then was i able to run the command npx react-native run-android smoothly.

I'm using Linux Mint and getting a similar error

$ npx react-native run-android
info JS server already running.
info Launching emulator...
error Failed to launch emulator. Reason: The emulator (telefon) quit before it finished opening. You can try starting the emulator manually from the terminal with: /home/furkan/Android/Sdk/emulator/emulator @telefon.
warn Please launch an emulator manually or connect a device. Otherwise app may fail to launch.

$ emulator -list-avds
telefon