Dart Unit Testing

Introduction to Dart Unit Testing

Unit testing is a crucial practice in software development, aimed at validating the smallest parts of an application, often called units. In Dart, unit testing is facilitated by the test package, which offers powerful tools to ensure your code behaves as expected.

In this guide, we will explore how to set up and run unit tests in Dart, focusing on the use of expect for function assertions.

Setting Up a Dart Unit Test

To begin unit testing in Dart, you need to include the test package in your pubspec.yaml file. This package provides the necessary functionality to write and execute tests.

Here's how you can add the package:

After adding the dependency, run pub get to install the package.

Writing Your First Unit Test

Let's write a simple unit test using Dart. Consider a function add that takes two integers and returns their sum:

To test this function, create a new file called test/add_test.dart and add the following code:

In this test, we use the test function to define a test case named "adds two numbers". Inside the test case, the expect function checks if the result of add(2, 3) is equal to 5 using the equals matcher.

Running the Tests

To execute your tests, run the following command in your terminal:

This command will run all test files in the test directory and display the results in the terminal, indicating whether your test passed or if there were any failures.

Advanced Assertions with Expect

The expect function is quite versatile and supports various matchers to perform complex assertions. Here are a few examples:

• equals: Checks if two values are equal.
• isNotNull: Verifies that a value is not null.
• throwsA: Asserts that a function throws a specific exception.