[C+ Checklist Needs Completion] [$500] Android - Scan - Second tap on capture button causes error to show up

[lanitochka17]

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Version Number: 1.4.41-3
Reproducible in staging?: Y
Reproducible in production?: Y
If this was caught during regression testing, add the test name, ID and link from TestRail:
Email or phone of affected tester (no customers):
Logs: https://stackoverflow.com/c/expensify/questions/4856
Expensify/Expensify Issue URL:
Issue reported by: Applause - Internal Team
Slack conversation:

Action Performed:

Precondition: Camera access is allowed

1. Launch New Expensify app
2. Tap + > Request money
3. Go to Scan
4. Tap on the capture button twice

Expected Result:

The second tap on the capture button should be disabled and no error will show up

Actual Result:

The second tap on the capture button is enabled, causing error to show up

Workaround:

Unknown

Platforms:

Which of our officially supported platforms is this issue occurring on?

• Android: Native
• Android: mWeb Chrome
• iOS: Native
• iOS: mWeb Safari
• MacOS: Chrome / Safari
• MacOS: Desktop

Screenshots/Videos

Add any screenshot/video evidence

Bug6379529_1707925292817.Screen_Recording_20240214_215216_New_Expensify.mp4

View all open jobs on GitHub

Upwork Automation - Do Not Edit

• Upwork Job URL: https://www.upwork.com/jobs/~017ba8b79a30323bee
• Upwork Job ID: 1757796267721375744
• Last Price Increase: 2024-02-14
• Automatic offers:
• hoangzinh | Reviewer | 0

[melvin-bot]

Job added to Upwork: https://www.upwork.com/jobs/~017ba8b79a30323bee

[melvin-bot]

Triggered auto assignment to Contributor-plus team member for initial proposal review - @hoangzinh (External)

[melvin-bot]

Triggered auto assignment to @greg-schroeder (Bug), see https://stackoverflow.com/c/expensify/questions/14418 for more details.

[lanitochka17]

We think that this bug might be related to #wave5
CC @quinthar

[agent3bood]

Proposal

Please re-state the problem that we are trying to solve in this issue.

Android - Scan - Second tap on capture button causes error to show up

What is the root cause of that problem?

This is multiple levels of issues causing the problem.

• In src/pages/iou/request/step/IOURequestStepScan/index.native.js the capturePhoto has an async operation, we need to return a Promise to make it work with the native implementation of singleExecution.
• The native implementation expects a promise to be returned for it to work, if we don't return a promise then the singleExecution will exit before the async operation has completed which means the function can be called again before the async function is completed.
• Current code execution flow is like this

// 1. `singleExecution` will make sure this is called just once 
capturePhoto() {
  // ... code
  
  // 2. this async callback function is added to the event loop to be executed in future tick/time.
  camera.current.takePhoto().then() => {
    // 4. some time later, the event loop will execute this code, it has nothing to do with `singleExecution`, and if the camera is busy it will throw.
  } 

  //
  // ... code
 // 3. function code is completed, `singleExecution` job is done here.
}

• We need to fix all components that wrap capturePhoto to return a Promise, and not ignore it, for example in here the promise is not returned properly.
• As for web, this is not an issue because the capturePhoto function is completely sync.

What changes do you think we should make in order to solve the problem?

• Make capturePhoto return a Promise.
• Fix all components that wrap capturePhoto to return a Promise, and not ignore it.
• Make sure I am not introducing new async operation when the callback is just a sync operation (i.e. do not do return new Promise(/* some sync result */))

// bad
return new Promise((resolve) => {
  const results = onPress(event);
  if(results instanceof Promise) {
    return results.finally(() => {resolve();});
  } 
});

// good
const results = onPress(event);
... other code might live here
return results;

What alternative solutions did you explore? (Optional)

See previous proposal.

original proposal

Proposal

Please re-state the problem that we are trying to solve in this issue.

Android - Scan - Second tap on capture button causes error to show up

What is the root cause of that problem?

In IOURequestStepScan.capturePhoto there is an async operation to capture the photo camera.current.takePhoto().then(), only after the async operation we do the navigation/error handling.
Between the time of requesting the first photo and getting the results if the user calls the capture button again, the camera is already busy and we get an error.

What changes do you think we should make in order to solve the problem?

Add a new flag capturePhotoInProgress and return early from capturePhoto if it is true. Set the variable to true when we start the function and reset it when it is done.

What alternative solutions did you explore? (Optional)

[Krishna2323]

Proposal

Please re-state the problem that we are trying to solve in this issue.

Android - Scan - Second tap on capture button causes error to show up

What is the root cause of that problem?

When we call capturePhoto is called we call camera.current.takePhoto which is a async operation and if we immediately call capturePhoto again the camera is busy and !camera.current is true.

App/src/pages/iou/request/step/IOURequestStepScan/index.native.js

Lines 234 to 237 in 04d7efd

	if (!camera.current) {
	showCameraAlert();
	return;
	}

What changes do you think we should make in order to solve the problem?

We need to use useSingleExecution to solve this bug.

Result

[EnderKilledYou]

So I see these on upwork. Are they taken or finished since they have a proposal? If I apply there am I wasting connects? I can update this one for sure. You can also disable the button or remove the click handler and add it back later.

[melvin-bot]

📣 @EnderKilledYou! 📣
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