How can I verify that a print is called for in dart unit tests?
I am writing a sample code for textbooks and want to try it out. There are many examples that use printing for simplicity. I want to run my unit tests to make sure the print is called with the correct input but I have a problem importing the main function in another dart file.
Thank you!
You can import any library, including a script with a main method. The problem is that your own script's main method shadows the import.
The solution is to import the library with a prefix:
import "other_library.dart" as testee;
void main() {
print("Testing something");
testee.main(); // Uses a prefixed name to avoid name conflict.
print("Testing done");
}
Related
I'm trying to write Dart code that will generate a rough equivalent of this:
var disposable = vscode['commands'].registerCommand(
'extension.sayHello',
function () {
vscode['window'].showInformationMessage('Hello World!');
}
);
context.subscriptions.push(disposable);
The variables vscode and context are both globals available in the JavaScript which is executing my Dart (which is being compiled to JS with the Dart Dev Compiler).
I'm happy for context/vscode to be completely untyped for now, but I'm struggling to bend the JS package to output code like this (eg. if I put #JS() on a stub vscode, I get dart.global.vscode).
You can use the base dart:js features
Note that context happens to be dart's name for the javascript context.
var disposable = context['vscode']['commands'].callMethod('registerCommand', [
'extension.sayHello',
() {
context['vscode']['window'].callMethod('showInformationMessage', ['Hello World!']);
}]);
);
context['context']['subscriptions'].callMethod('push', [disposable]);
Let me put together a quick example on github with package:js.
Edit: OK, here you go:
https://github.com/matanlurey/js-interop-examples
It took me a couple tries to the package:js syntax correct (we probably need more documentation here and examples), but I ended up creating a "fake" visual studio code API (vscode.js), and interoping with it fine.
Watch out that you need to wrap your functions with allowInterop if you expect your examples to work in Dartium.
** This question is edited and cleaned up some **
I have two projects and I want to use code from one in the other; I seem to be having trouble putting the code in the right directory structure to make the import statements work.
Both projects are created and managed exclusively from the Dart Editor on a Mac, if that makes any differences.
Project Directory Structures
Project 1: a command line app which contains the code I want to share in the following directory structure:
/dart/command_line_app
/lib
shared_library.dart
/bin
command_line_app.dart
Project 2: a web app which wants to import the code in shared_libary.dart
/dart/web_application
/packages
/web
web_application.dart
In the file shared_libary.dart, I declare it to be a library can create a simple class that provides output when instantiated:
library shared_library;
class ShareMe
{
ShareMe()
{
print("Hello, ShareMe");
}
}
This compiles, and works inside the command_line project: command_line_app.dart has the following:
import 'package:command_line_app/shared_library.dart';
void main() {
ShareMe shareMe = new ShareMe();
print("Hello, World!");
}
This imports the code runs, printing both "Hello Share Me," and Hello World.
THE PROBLEM
I want to instantiate the ShareMe class inside web_application.dart. I'd thought I could do that by putting in the same import statement I put in my command_line code:
import 'package:command_line_app/shared_library.dart';
But, when I put the same import into the web_appliation, it gets the error
Target of URI does not exist 'package:command_line_app/shared_library.dart'
Other Things I've Tried
I was certain I'd solved the problem when I cntrl-Clicked properties on Web_application and selected Project References.
It brings up a window allowing me to select command_line_app with a check box, but when I do, I get an error:
Could not set the project description for 'web_application' because the project description file (.project) is out of sync with the file system.
Whatever that means.
When I cntrl-click the underlined error and try Quick Fix it offers me "resolve dependencies" which sounds promising, but after a few seconds, it comes back and informs me that
Pub get failed, [1] Resolving dependencies... (15.3s)
Could not find package command_line_app at https://pub.dartlang.org.
Depended on by:
- web_application 0.0.0
I hope this is clear-er and gives a better insight into both what I'm trying to do and what I'm missing.
EDIT
you need to add
dependencies:
command_line_app:
path: ../command_line_app
to your dependencies in web_application/pubspec.yaml.
EDIT END
When you want to make code reusable in different packages, you should put that code into the lib directory of that package and import it using import 'package:mypackage/myfile.dart';.
Another problem you may face is, that browser applications can't import packages that have a dart:io dependency. If you want to reuse code between command line and browser applications you should move them into the lib directory of another package my_shared_code where you put only code that doesn't depend on dart:io (for example some entity classes) and import this code from both app packages (browser and command line).
Say, I load this script in the browser:
<script src='app.dart' type='application/dart'></script>
Now, in app.dart I have this:
import 'library1.dart';
unleashTheKraken();
Then in library1.dart you'll find this:
library library1;
import 'library2';
And finally in library2.dart we'll have:
library library2;
unleashTheKraken() => print('Unleashing the Kraken')
And the result is: Exception: No top-level method 'unleashTheKraken' declared. How so?
Because imports don't chain automatically. You have to use the export statement for that.
library library1;
import "library2.dart";
export "library2.dart";
And to avoid unnecessary code: import and export are completely independent. If you don't use unleashTheKraken in library1 itself, you can omit the import statement and just use export alone.
I know you can use the library, import and even #import, but which is correct?
I have got two files, MainClass.dart and Library.Dart, and I want to add a reference to Library.dart in MainClass.dart. How can I do that?
Firstly let me just preface this by saying please do not use the hash symbol before import or library or anything else. This is an old syntax that is being deprecated. So we no longer want to use #import('...') The correct syntax is:
import 'some_file.dart';
That said, there are two different things we can do to access different dart source files within our current file. The first is to import the file. We use this such as in your case when you want to bring a different library into the current file (or more accurately current library).
Usually if your files are in the same directory, or a sub directory of the current one we would import them like this:
import 'lib/library.dart';
However If you are using the pub package layout you can also use some special short-cut references as well to import files (particularly from other packages you've imported). I highly suggest reading the documents on the pub site, as most applications and libraries are designed with this in mind. It also has suggestions on best naming conventions such as filenames in all lower case, and using underscore for spaces, and directory layouts.
The other important thing to know about bringing a dart file into another file, is that we can use the part and part of directives. This used to be called #source but was changed (with the removal of the hash sign) to reduce confusion. The part directive is used when we want to write a single library which spans multiple files. Say for instance you have an Awesome Library, which is starting to get a little large for a single file. We will create the main file of the library (not to be confused with the main method). This file will usually have the same name as the library itself.
// awesome_library.dart
library awesome_library;
import 'dart:math';
import '...';
// this injects all the content of secret_file.dart
// into this file right here almost as if it was
// here in the first place.
part 'src/secret_file.dart';
// The rest of our file here
// ...
The part directive basically takes everything from our src/secret_file.dart and inserts it into that part of the file. This allows us to split our huge Awesome Library into multiple smaller files that are easier to maintain. While not specifically required, it is helpful to use the part of directive in our secret_file.dart to help the editor know that it is "part of" the library.
// secret_file.dart
part of awesome_library;
// ... Rest of our secret_file code below.
Note that when using a part file like this, the part(s) (that is everything that is not the main file of the library) cannot import or use library declarations themselves. They import whatever is imported into the the main file, but they cannot add any additional imports.
For more information about library see this link.
Importing your own created libraries:
You will be importing the filename.dart and not the name of your library.
So if the name of your library is: myLib and it is saved in the file: someDartFile.dart you will have to
import 'someDartFile.dart';
If you have on Windows a library at: K:\SomeDir\someFile.dart you will need to write:
import '/K:/SomeDir/someFile.dart';
example:
import 'LibraryFile.dart'; //importing myLib
void main(){
//a class from myLib in the LibraryFile.dart file
var some = new SomeClassFromMyLibrary();
}
myLib in LibraryFile.dart:
library myLibrary;
import 'dart:math';
class SomeClassFromMyLibrary{
String _str = "this is some private String only to myLibrary";
String pubStr = "created instances of this class can access";
}
Here a full example.
//TestLib.dart
import 'LibFile.dart'; //SomeLibrary
void main() {
print("Hello, World!");
LibFile l = new LibFile();
print(l.publicString);//public
print(l.getPrivateString);//private
print(l.getMagicNumber); //42
}
//LibFile.dart
library SomeLibrary;
part 'LibFile2.dart';
class LibFile {
String _privateString = "private";
String publicString = "public";
String get getPrivateString => _privateString;
int get getMagicNumber => new LibFile2().number;
}
//LibFile2.dart
part of SomeLibrary;
class LibFile2 {
int number = 42;
}
Although i am answering very late, but the answer may help new developer.
Always use pubspec.yaml file in your dart package(application/library).
once you run pub get command it will add your local library in the dependencies list in .packages file.
Consider i have following project structure.
To refer to the content of greeting.dart in my main.dart file i should add the library as below
import 'package:my_project_name/greeting.dart'
Once imported we can use the content of greeting.dart file in our main.dart file.
Note: we have not used the actual path as you can see 'lib' directory is missing.
First make sure that's the name which you have mentioned in pubspec.yaml and the file you want to import are sharing the exact same name
example:
pubspec.yaml
name: flutter_wordpress_app
description: flutter wordpress app
...
....
// dirOne/dirTwo/greeting.dart
class FavArticleBloc {
// Your code goes here
}
import 'package:flutter_wordpress_app/dirOne/dirTwo/greeting.dart'
void main(){
var some = new FavArticleBloc();
}
But
in the main.dartyou don't need to specify
import 'package:flutter_wordpress_app
just do like below
import 'dirOne/dirTwo/greeting.dart
So I have two dart files -- One defines the entry-point Main() and the other is a class I've created. The Main file #imports dart:html and #sources my class. My class uses the dart:html namespace, and Dart Editor will display errors if I don't #import it. However, my class will fail to compile if I #import dart:html since the Main file already does, but compiles fine without the #import. Is there a way to appease the dart editor, or is this a known issue with how the dart editor resolves namespaces?
You should only do the import once and then source your program files from your main file. Something like this:
main.dart
#import("dart:html");
#source("program.dart");
main() {
var program = new Program();
program.run();
}
program.dart
class Program {
run() {
var elm = new Element.html("<p>hello world</p>");
document.body.nodes.add(elm);
}
}
should definitely work.