Dart Unit Testing
Unit Testing Task
The task for unit testing is listed below.
- Unit Test Plan
Prepare
Review
Rework
Baseline - Unit Test Cases/Scripts
Prepare
Review
Rework
Baseline - Unit Test
Perform
Advantage of Unit Testing
Below are a few benefits of unit testing.
1.We can easily maintain code.
2.It increases code reusability.
3.Development is accelerated by it.
4.Debugging the code is a simple process.
5.Due to the early detection of errors, it can identify the cost of testing and defect repair.
Dart Unit Testing
It is necessary to include the external library “test” in Dart in order to write and execute individual unit tests in a standard manner. The following procedures can be used to accomplish unit testing.
Step – 1: Installing “test” package
We need to install a third-party package called “test” in our ongoing working project before we can incorporate unit testing into it. Now that the pubspec.yaml file is open in our project, type the following text.
dependencies:
test:
Now select Pub: obtain dependencies by doing a right-click on the pubspec.yaml file. The “test” package will be installed in our project as a result.
We can use the following command to install it as well.
pub get
Step – 2: Importing “test” package
To import the “test” package into your project, type the following line.
import "package:test/test.dart";
Step – 3: Writing Test Cases
The Test cases add the top-level method test(). We use the expect() method in the test() function to create the test assertion. ActualValue and MatchValue are the two arguments that the expert() function accepts.
Syntax
test("Test Description", () {
expert(actualValue, matchingValue)
});
Group of Test Cases
With the group() function, we may put several test cases together into a group. It facilitates test case grouping according to certain standards. Each group’s description is given at the outset of the exam description.
Syntax
group("Test_Group_Name", () {
test("test_case_name_1", () {
expect(actual, equals(exptected));
});
test("test_case_name_2", () {
expect(actual, equals(expected));
});
})
Example - Passing Test
This is an example of how to define a unit test add() method. It returns an integer that represents the total of the two integer parameters that it accepts. Learn how to use the add() method by understanding this example:
Step 1: The test package is imported.
Step 2: The test is defined using the test() method, and an assertion is imposed using the expert() function.
import 'package:test/test.dart';
// Importing the test package
int add(int x,int y)
// this function to be tested {
return x+y;
}
void main() {
// Defining the test function
test("test to check add method",(){
// Arrange
var expected = 30;
// Act
var actual = add(10,20);
// Asset
expect(actual,expected);
});
}
Output
00:00 +0: test to check add method
00:00 +1: All tests passed!
Example - A unsuccessful Test
We define a logical error in the sub() method. Let’s look at the next illustration.
import 'package:test/test.dart';
int add(int x,int y){
return x+y;
}
int sub(int x,int y){
return x-y-1;
}
void main(){
test('test to check sub',(){
var expected = 10;
// Arrange
var actual = sub(30,20);
// Act
expect(actual,expected);
// Assert
});
test("test to check add method",(){
var expected = 30;
// Arrange
var actual = add(10,20);
// Act
expect(actual,expected);
// Asset
});
}
Output
00:00 +0: test to check sub
00:00 +0 -1: test to check sub
Expected: <10>
Actual: <9>
package:test expect
bin\Test123.dart 18:5 main.<fn>
00:00 +0 -1: test to check add method
00:00 +1 -1: Some tests failed.
Unhandled exception:
Dummy exception to set exit code.
#0 _rootHandleUncaughtError.<anonymous closure> (dart:async/zone.dart:938)
#1 _microtaskLoop (dart:async/schedule_microtask.dart:41)
#2 _startMicrotaskLoop (dart:async/schedule_microtask.dart:50)
#3 _Timer._runTimers (dart:isolate-patch/timer_impl.dart:394)
#4 _Timer._handleMessage (dart:isolate-patch/timer_impl.dart:414)
#5 _RawReceivePortImpl._handleMessage (dart:isolate-patch/isolate_patch.dart:148)
The add() function in the example above passes the test, but the sub() function’s logical fault caused it to fail the unit test.
Grouping Test Cases
Multiple test cases can be written in a group format. These methods are grouped together using the group() function. Writing much cleaner code is helpful.
We are creating a test case for the divide() and trim() functions in the example that follows. These functions were combined and given the name String.
Example
import "package:test/test.dart";
void main() {
group("String", () {
// First test case
test("testing on split() method of string class", () {
var string = "Hii,Hello,Hey";
expect(string.split(","), equals(["Hii", "Hello", "Hey"]));
});
// Second test case
test("testing on trim() method of string class", () {
var string = " Hii ";
expect(string.trim(), equals("Hii"));
});
});
}
Output
00:00 +0: String testing on split() method of string class
00:00 +1: String testing on trim() method of string class
00:00 +2: All tests passed
