Dart
Integration tests
Learn to write integration tests.
Integration tests
An integration test verifies that multiple components work together. While a unit test isolates a single function, an integration test exercises the whole flow.
In Dart the integration_test package runs in a real environment. Widget tests use testWidgets; the end-to-end flow is exercised.
Advantage: catches integration bugs between components. Disadvantage: slower than unit tests. Therefore few integration, many unit tests are recommended.
Expectations and setup
The building block of tests is the expect(actual, expected) assertion. setUp runs before each test, tearDown after each test.
In integration tests setUp can start a real database or HTTP server. This makes the test realistic but slower.
group('addition', () { ... }) groups related tests. A separate setUp can be written per group; this organizes tests neatly.
Exercise Define a Calculator and an expect
Define a Calculator class with int add(int a, int b) => a + b;. Define a void expect(dynamic actual, dynamic expected, String label) function with body { if (actual == expected) { print('PASS: $label'); } else { print('FAIL: $label'); } }. In main create final calc = Calculator(); and call expect(calc.add(2, 3), 5, 'add');.
Show example solution
class Calculator {
int add(int a, int b) => a + b;
}
void expect(dynamic actual, dynamic expected, String label) {
if (actual == expected) {
print('PASS: $label');
} else {
print('FAIL: $label');
}
}
void main() {
final calc = Calculator();
expect(calc.add(2, 3), 5, 'add');
}
Test yourself
-
What does an integration test verify?
- A single function
- That components work together
- One line of code
- Only imports
Show answer
That components work together — an integration test verifies a multi-component flow.
-
The test function
void main() {
____('addition works', () {
expect(2 + 3, 5);
});
}
Show answer
void main() {
test('addition works', () {
expect(2 + 3, 5);
});
}
-
Match the test parts
- integration_test
- Package
- testWidgets
- Widget test
- expect
- Assertion
- setUp
- Setup
Next lesson: Property tests
