In this tutorial for AngularDart:
https://angulardart.dev/tutorial/toh-pt6#herosearchcomponent
A couple of deprecated Dart functions are used:
(1) debounce()
from package:stream_transform/src/rate_limit.dart
(2) switchMap()
from package:stream_transform/src/switch.dart
So, the following function (in tutorial) does not work any more:
////////////////////////////////////////////////////////////
void ngOnInit() async {
heroes = _searchTerms.stream
.transform(debounce(Duration(milliseconds: 300)))
.distinct()
.transform(switchMap((term) => term.isEmpty
? Stream<List<Hero>>.fromIterable([<Hero>[]])
: _heroSearchService.search(term).asStream()))
.handleError((e) {
print(e);
});
}
////////////////////////////////////////////////////////////
How to make the tutorial app work again?
Found the solution.
Simply remove the "transform" part.
Related
Suppose we need to execute some code when a function finishes, no matter how.
Example:
void myFunc() async {
await myLock.acquire();
if(...) {
myLock.release();
return;
}
...
myLock.release();
}
Many languages have features that allow to achieve this in a more elegant way than just manually calling myLock.release() before every return statement (For example defer in Go). Is something like that also possible in Dart?
Dart does not have RAII. You instead would need to use try-finally.
(Dart did recently (in 2.17) add Finalizers, but those would fire when objects are garbage collected, which might happen at some non-deterministic time, if ever.)
And just for the record, an example of using try/finally:
void myFunc() async {
await myLock.acquire();
try {
if(...) {
return;
}
...
} finally {
myLock.release();
}
}
You'd want to start the try after allocating the resource, so that you don't try to release if allocation throws.
How to add something like isClickable() in my appium native app tests. I have written my tests, however they are very flaky and fail sometimes because it cannot find the element. I am thinking about making custom click and set value functions with the implicit wait times.
I thought about using isClickable() but the appium documentation says - Please note that isClickable works only in web and webviews, it doesn't work in mobile app native context.
Is there any other alternative i can use? can i use smartwait? if yes how can i implement that
Here is how i am defining home.screen.js
import AppScreen from './app.screen';
const SELECTORS = {
HOME_SCREEN: '~homeBarButton',
PRODUCTSEARCH_SCREEN: '~productSearchBarButton',
CUSTOMERSEARCH_SCREEN: '~customersBarButton',
STOREHUB_SCREEN: '~storeHubBarButton',
SETTING_ICON: '~SettingsIcon',
LOGOUT_BUTTON: '~settingsMainLogoutButton'
};
class HomeScreen extends AppScreen {
constructor () {
super(SELECTORS.HOME_SCREEN);
}
get homescreenButton () {
return $(SELECTORS.HOME_SCREEN);
}
get productsearchField () {
return $(SELECTORS.PRODUCTSEARCH_SCREEN);
}
get customersearchButon () {
return $(SELECTORS.CUSTOMERSEARCH_SCREEN);
}
get storehubButon () {
return $(SELECTORS.STOREHUB_SCREEN);
}
get settingIcon () {
return $(SELECTORS.SETTING_ICON);
}
get logoutButton () {
return $(SELECTORS.LOGOUT_BUTTON);
}
}
export default new HomeScreen();
And i am writing my test like this test.js:
import HomeScreen from '../screenobjects/home.screen';
import FormScreen from '../screenobjects/forms.screen';
import CommonPage from '../pageobjects/common.page';
describe('Sending item successfullt,', () => {
beforeEach(() => {
CommonPage.login()
});
afterEach(() => {
CommonPage.logout()
});
it('should be able to send the item to the mirror', () => {
driver.pause(3000)
HomeScreen.productsearchField.click();
driver.pause(3000)
HomeScreen.customersearchButon.click();
});
});
As you can see above, I have to add driver.pause otherwise my tests would fail because of button not clickable or typeable.
My suggestion is that you can get your elements attribute clickable and if its true keep doing your things
public boolean isClickable(String element) {
return androidDriver.findElementByAccessibilityId(element).getAttribute("clickable").equals("true");
}
You can use any method to find your element.
Best approach is to stop using implicit waits and do an explicit wait before each driver UI interaction.
You should do some reading on waitUntil / WebDriverWait (not sure if you have that in node.js implementation).
Then create functions for interacting with all types of elements in your app that perform an explicit wait before execution.
Pseudo code:
get clickButton (Selector element) {
waitUntil(clickable(element),...);
return $(driver.click(element));
}
Write generic methods for all type of elements in your app (button, textfield, dropdown...) and remove implicit waits from driver. You will see a big difference in your test stability.
Is there an expiring map in dart ? I'm looking for something similar to PassiveExpiringMap in Apache common.
Thanks in advance.
There doesn't seem to be a package for this. However, in case anyone is just looking for a quick snippet to lazily copy and paste like I did, here's a start you can taylor to your needs:
class ExpiringMap {
final Map<dynamic, dynamic> _map = {};
Object operator [](Object key) => _map[key];
void operator []=(Object key, Object value) {
_map[key] = value;
Future.delayed(Duration(minutes: 1), () => _map.remove(key));
}
}
I am new to Dart programming. I am trying to figure out what is the proper way (what everyone will do) to handle/guard those functions which are login required. The following is my first trial:
$ vim login_sample.dart:
var isLoggedIn;
class LoginRequiredException implements Exception {
String cause;
LoginRequiredException(this.cause);
}
Function loginRequired(Function f) {
if (!isLoggedIn) {
throw new LoginRequiredException("Login is reuiqred.");
}
return f;
}
void secretPrint() {
print("This is a secret");
}
void main(List<String> args) {
if (args.length != 1) return null;
isLoggedIn = (args[0] == '1') ? true : false;
try {
loginRequired(secretPrint)();
} on LoginRequiredException {
print("Login is required!");
}
}
then, run it with $ dart login_sample.dart 1 and $ dart login_sample.dart 2.
I am wondering if this is the recommended way to guard login required functions or not.
Thank you very much for your help.
Edited:
My question is more about general programming skills in Dart than how to use a plugin. In python, I just need to add #login_required decorator in the front of the function to protect it. I am wondering if this decorator function way is recommended in dart or not.
PS: All firebase/google/twitter/facebook etc... are blocked in my country.
I like the functional approach. I'd only avoid using globals, you can wrap it in a Context so you can mock then for tests and use Futures as Monads: https://dartpad.dartlang.org/ac24a5659b893e8614f3c29a8006a6cc
Passing the function is not buying much value. In a typical larger Dart project using a framework there will be some way to guard at a higher level than a function - such as an entire page or component/widget.
If you do want to guard at a per-function level you first need to decide with it should be the function or the call site that decides what needs to be guarded. In your example it is the call site making the decision. After that decision you can implement a throwIfNotAuthenticated and add a call at either the definition or call site.
void throwIfNotAuthenticated() {
if (!userIsAuthenticated) {
throw new LoginRequiredException();
}
}
// Function decides authentication is required:
void secretPrint() {
throwIfNotAuthenticated();
print('This is a secret');
}
// Call site decides authentication is required:
void main() {
// do stuff...
throwIfNotAuthenticated();
anotherSecreteMethod();
}
Consider code like this:
import 'dart:async';
foo() {
new Timer(onesec, bar);
}
bar() {
throw "from bar";
}
const onesec = const Duration(seconds:1);
main() {
runZoned(() {
new Timer(onesec, foo);
},
onError: (e, stackTrace) => print(stackTrace));
}
How can I tell that bar was "called" by foo in the stackTrace that I print out?
I'd like to see something like:
bar
...
foo
...
main
Have a look at the stack_trace package. It uses zones to keep track of asynchronous callbacks. Capturing stack traces for every asynchronous callback is expensive, but for debugging it is definitely worth it.
Example output from the package:
http://dartlang.org/foo/bar.dart 10:11 Foo.<fn>.bar
http://dartlang.org/foo/baz.dart Foo.<fn>.bar
===== asynchronous gap ===========================
http://dartlang.org/foo/bang.dart 10:11 Foo.<fn>.bar
http://dartlang.org/foo/quux.dart Foo.<fn>.bar
According to the doc, the easiest way to get these traces is to use Chain.capture.