Summary - Testing

Combine test, expect and mock to write a calculator test.

Summary: Testing

In this group you saw the dart test framework, test and expect, organization with group, fixtures with setUp/tearDown and mocks. Tests guarantee your code's correctness.

Now we combine them: we will write a testable Calculator class and print its result. This is the cornerstone of testing.

Remember: each test probes one behavior; setUp builds a clean environment; mocks keep external dependencies out.

Exercise Calculator: add and subtract

Define a Calculator class with int add(int a, int b) => a + b; and int subtract(int a, int b) => a - b; methods. In main print the results of add(10, 3) and subtract(10, 3) on separate lines with print.

Show example solution

class Calculator {
  int add(int a, int b) => a + b;
  int subtract(int a, int b) => a - b;
}

void main() {
  var c = Calculator();
  print(c.add(10, 3));
  print(c.subtract(10, 3));
}

Test yourself

Concept matching

test()

Test block
expect()

Assertion
group()

Organization
setUp()

Fixture
What does setUp provide?
- Throws an error
- A clean fixture
- Sets up a loop
- Creates a mock
Show answer

A clean fixture — setUp provides a clean fixture.

The expect matcher

expect(result, ____(5));

Show answer

expect(result, equals(5));

Next lesson: dart:io

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