For closing current tab in my test I use next function:
browser.getAllWindowHandles().then((handles) => {
browser.driver.switchTo().window(handles[1]);
browser.driver.close();
browser.driver.switchTo().window(handles[0]);
});
And it works good. But I must rewrite to "async/await" instead of ".then". I try next code:
async function goBackToPreviousTab () {
let handles = await browser.getAllWindowHandles();
browser.driver.switchTo().window(handles[1]);
browser.driver.close();
browser.driver.switchTo().window(handles[0]);
}
but in result receive next error:
no such window: target window already closed
from unknown error: web view not found
First of all, understand that .then or await is a way of resolving Promises. So whatever returns a promise needs to be explicitly resolved. For example, .close() returns a Promise too, and needs either of the syntax
This is why, back your question, your function should be
async function goBackToPreviousTab () {
let handles = await browser.getAllWindowHandles();
await browser.driver.switchTo().window(handles[1]);
await browser.driver.close();
await browser.driver.switchTo().window(handles[0]);
}
because each of your commands is a Promise
Related
I am using flutter with the cbl package to persist data. Trying to retrieve the entries does not seem to work because the function created is returning at the await statement and not the return statement. This does not seem like the intended result of darts async/await functionality. So I am lost.
task_database.dart
Future<dynamic> getAllTasks() async {
final tasksDb = await Database.openAsync(database); <---------- Returns here
var tasksQuery = const QueryBuilder()
.select(SelectResult.all())
.from(DataSource.database(tasksDb));
final resultSet = await tasksQuery.execute();
late var task;
await for (final result in resultSet.asStream()) {
final map = result.toPlainMap();
final taskDao = TaskDao.fromJson(map);
task = taskDao.task;
// Do something with the task...
print(task);
}
;
return task; <-------------------------------------------- Does not make it here
}
task_cubit.dart
getAllTasks() => {
allTaskMap = TasksAbcDatabase().getAllTasks(),
emit(TaskState(tasks: state. Tasks))
};
What I have tried. I have tried to use Database.openSync instead of Database.openAsync however, the function just returns at the next await statement. I have also tried making getAllTasks asynchronous and awaiting the database as such.
Future<void> getAllTasks() async => {
allTaskMap = await TasksAbcDatabase().getAllTasks(),
emit(TaskState(tasks: state. Tasks))
};
However this has the same issue, when the function from task_database returns prematurely it the returns at the first await function in getAllTasks which is the allTaskMap variable.
Thanks
A function cannot "return prematurely" without a return statement.
The only way the execution is cut short would be an exception being thrown.
I also don't see how you don't get syntax errors, when you don't await the Database.openAsync(database) statement.
So make sure all your awaits are in place. Use the linter to find those that are missing. While you are at it, remove the keyword dynamic from your vocabulary, it will only hurt you if you use it without a need for it. Your return type should be properly typed, then your compiler could tell you, that returning a single task from a function that is clearly supposed to return multiple tasks is not going to work.
Either catch your exceptions and make sure you know there was one, or do not catch them and watch them go all the way through into your debugger.
In addition, following the comment of #jamesdlin, your function definitions are... valid, but probably not doing what you think they are doing.
Future<void> getAllTasks() async => {
allTaskMap = await TasksAbcDatabase().getAllTasks(),
emit(TaskState(tasks: state. Tasks))
};
needs to be
Future<void> getAllTasks() async {
allTaskMap = await TasksAbcDatabase().getAllTasks();
emit(TaskState(tasks: state. Tasks));
}
var a = await () async {try{return await ... }}.call();
I was thinking that way to write is not convenient, they are so verbose.
"await () async {...}" is a very ugly style.
What I'm wrong? There is another way to do this?
var a = await () async
{
try {
return await method();
} catch (e) {
return anotherMethod();
}
}.call();
EDIT:
The return inside the try block send the value to a variable "a". Otherwise, I had to: First: declare a variable Then: set the value inside the try-catch block.
This kind of structure can easily drive you to fail, once that you don't have any guarantee that the variable are true set.
By the other hand: with an inline function you have to return any value otherwise the compile alert by the ERROR. And you get a more refactorable code;
I have this code :
widget.items.sort((a, b) {
await getItemDistance(a, true);
await getItemDistance(b, false);
return (itemADistance)
.compareTo(itemBDistance);
});
I am trying to sort widget.items list based on values returned from getItemDistance. However I get an error with a red squiggly line that says :
The await expression can only be used in an async function
and when I try to add async to the sort method I get another red squiggly line that says :
The argument type 'Future Function(Item, Item)' can't be assigned
to the parameter type 'int Function(Item, Item)'
How do I solve this dilemma guys ? :)
Thanks
List.sort is a synchronous function that expects a synchronous callback; there is no way to use it with an asynchronous callback. I would recommend transforming your List and doing any necessary asynchronous work first and then synchronously sorting the results. Doing so also should avoid calling getItemDistance (which, by virtue of being asynchronous, is likely to be expensive) on the same item multiple times. For example, something like:
final computedDistances = <Item, double>{};
for (final item in widget.items) {
final distance = await getItemDistance(item, ...);
computedDistances[item] = distance;
}
widget.items.sort((a, b) =>
computedDistances[a].compareTo(computedDistances[b])
);
(I don't know what the second argument to getItemDistance represents; if you can't get around that, you would need to build one Map with getItemDistance(..., true) results and one with getItemDistance(..., false) results1.)
As a last resort, you could write your own asynchronous sort function.
Edit #1
This should be a more efficient version since it doesn't wait for each asynchronous operation one-by-one:
final computedDistances = await Future.wait<double>([
for (final item in widget.items) getItemDistance(item, ...),
]);
final computedDistancesMap = <Item, double>{
for (var i = 0; i < widget.items.length; i += 1)
widget.items[i]: computedDistances[i],
};
widget.items.sort((a, b) =>
computedDistancesMap[a].compareTo(computedDistancesMap[b])
);
Edit #2
I've added a List.sortWithAsyncKey extension method to package:dartbag that can do this :
await widget.items.sortWithAsyncKey(
(element) => getItemDistance(element, ...),
);
1 However, if you need to call getItemDistance(..., true) for the first argument and getItemDistance(..., false) for the second argument, that implies that your comparison function probably is not self-consistent.
Whenever you are running async code you should add the async keyword like below. this tells dart you intend to run async code.
Async functions return a Future which tells dart that at some point in the future you are expecting itemADistance or an error.
You will want to return a Future of type int since you are expecting to receive an int itemADistance or an error.
Future<int> widget.items.sort((a, b) async {
await getItemDistance(a, true);
await getItemDistance(b, false);
return (itemADistance)
.compareTo(itemBDistance);
});
I wrote a pack of tests and separately each of them works correctly (for each test I created separate file - it important for my case) , but when I try to run them all together I have some problems:
At the first I tried to restart browser after each test with “restartBrowserBetweenTests: true” option but as a result I receive next error:
Failed: This driver instance does not have a valid session ID (did you
call WebDriver.quit()?) and may no longer be used.
I read some advice for this situation, but nothing helped me.
Basically, I can get without restarting browser but in this case I want to close all active tabs after each test and I also don’t know ho to do it. With the help of this function:
browser.getAllWindowHandles().then((handles) => {
browser.driver.switchTo().window(handles[1]);
browser.driver.close();
browser.driver.switchTo().window(handles[0]);
});
I can close active tab and return for the previous but the function works only if I place this code in the test spec, that's not comfortable for me (copy it for each test) and if I call it from special file with functions it works incorrectly due to the
“Failed: no such window: target window already closed
from unknown error: web view not found”
errors (a consequence of a lost context).
https://www.protractortest.org/#/api?view=ProtractorBrowser.prototype.restart
use instead:
browser.restart()
also try to use await
it('Test Puppeteer screenshot', async function() {
await browser.get('https://www.google.com')
let current = await browser.getWindowHandle()
await browser.executeScript("window.open('https://www.indiatoday.com')")
handles = await browser.getAllWindowHandles()
await browser.switchTo().window(handles[1]);
await browser.close();
await browser.switchTo().window(handles[0]);
});
Note if you are using page object the nyou have to reinitialize modules:
if you are using javascript object notation for page then
https://www.npmjs.com/package/decache
const decache = require('decache');
let stage1 = require('../pageobjects/stage1.js');
beforeEach(async function () {
decache('../pageobjects/stage1.js');
stage1 = require('../pageobjects/stage1.js');
elements = stage1.elements;
});
If you are using nodejs class:
let stage1 = require('../pageobjects/stage1.js');
beforeEach(async function () {
stage1 = new PageObjects.stage1();
});
This because the reference for elements have changed you have to reinitialize them
Help is much appreciated how to trace down this issue, because I am running out of ideas.
I am calling the function getOrderCollection, below, but it aborts after the first line var myCompanyDoc = await FirebaseFirestore.instance.collection('companies').doc(myCompany).get(); Without trowing anything to the console or jumping into some library when debugging. When I click next statement it jumps back to the calling function.
I am authenticated to the database, companyCollection = FirebaseFirestore.instance.collection('companies') provides an initialized object pointing to the collection and myCompany is a constant with the document id entered by copy/paste.
If some rules for the database but I can't see successful or denied queries with the monitor.
Any ideas how I can proceed tracing down the issue?
Future<void> getOrderCollection() async {
var myCompanyDoc = await FirebaseFirestore.instance.collection('companies').doc(myCompany).get();
print("companyDoc fetched");
final myDeliveryDocRef = myCompanyDoc.data()['delivery'].toString();
orderCollection = FirebaseFirestore.instance.collection('companies').doc(myCompany).collection('features').doc(myDeliveryDocRef).collection('orders');
orderBriefDoc = FirebaseFirestore.instance.collection('companies').doc(myCompany).collection('features').doc(myDeliveryDocRef);
}
UPDATE: This is collection > document what corresponds to final String myCompany = '4U4kZKXkr3rHA6B04S5K';
As we discussed in your comments, the issue was that you forgot to await the getOrderCollection() function. Even though, as you mentioned, your caller function _deliveryRepository.initRepository() was awaited, you still had to await getOrderCollection() inside your caller method to make sure that the code is waiting for the getOrderCollection() to be executed before it proceeds to the next line.
In general, you want to have some error handling and to type the known types/classes (avoid using var).
Error handling - for async/await place the code inside a try/catch.
Typing - Dart is type safe, which is really great to prevent runtime errors.
Depending on your setup, you might be able to hover over the Firestore.instance.collection(...).doc(...) to see the return type. .doc(...).get() returns a DocumentSnapshot and .collection(...).get() returns a CollectionSnapshot.
Using the above, it should be easier to debug:
Future<void> getOrderCollection() async {
try {
DocumentSnapshot myCompanyDoc = await FirebaseFirestore.instance.collection('companies').doc(myCompany).get();
print("companyDoc fetched");
final myDeliveryDocRef = myCompanyDoc.data()['delivery'].toString();
} catch(e) {
print('Error: ' + e.toString());
}
}
Don't forget to await your other 2 Firestore queries.