This library accesses the International Space Station‘s APIs (using package:http) to fetch the space station’s current location.
The unit tests for this library use package:mockito to generate preset values for the space station's location, and package:test to create reproducible scenarios to verify the expected outcome.
The ISS library, iss.dart, consists of two classes:
IssLocator : Fetches the current GPS position directly under the space station.
IssSpotter : Performs calculations from the observer's location on earth.
The unit test, iss_dart.test, mocks the IssLocator class:
// The Mock class uses noSuchMethod to catch all method invocations.
class MockIssLocator extends Mock implements IssLocator {}
The tests check for two scenarios:
Spherical distance : Given two predefined points on earth, verify the calculated distance between them.
group('Spherical distance', () {
test('London - Paris', () {
Point<double> london = new Point(51.5073, -0.1277);
Point<double> paris = new Point(48.8566, 2.3522);
double d = sphericalDistanceKm(london, paris);
// London should be approximately 343.5km
// (+/- 0.1km) from Paris.
expect(d, closeTo(343.5, 0.1));
});
test('San Francisco - Mountain View', () {
Point<double> sf = new Point(37.783333, -122.416667);
Point<double> mtv = new Point(37.389444, -122.081944);
double d = sphericalDistanceKm(sf, mtv);
// San Francisco should be approximately 52.8km
// (+/- 0.1km) from Mountain View.
expect(d, closeTo(52.8, 0.1));
});
});
ISS Spotter : Stubs IssLocator.currentPosition using when().thenReturn(). Evaluate whether the space station (using a predefined location) is visible from a second predefined location. This test runs asynchronously.
group('ISS spotter', () {
test('ISS visible', () async {
Point<double> sf = new Point(37.783333, -122.416667);
Point<double> mtv = new Point(37.389444, -122.081944);
IssLocator locator = new MockIssLocator();
// Mountain View should be visible from San Francisco.
when(locator.currentPosition).thenReturn(sf);
var spotter = new IssSpotter(locator, mtv);
expect(spotter.isVisible, true);
});
test('ISS not visible', () async {
Point<double> london = new Point(51.5073, -0.1277);
Point<double> mtv = new Point(37.389444, -122.081944);
IssLocator locator = new MockIssLocator();
// London should not be visible from Mountain View.
when(locator.currentPosition).thenReturn(london);
var spotter = new IssSpotter(locator, mtv);
expect(spotter.isVisible, false);
});
});
iss.dart : International space station API library
iss_test.dart : Unit tests for iss.dart library