This document provides an introduction to unit testing Mule flows using Munit. It defines what a unit test is and characteristics of good unit tests. Reasons for writing unit tests are given such as reducing bugs and improving design. Dependencies for Munit unit testing like JUnit and Munit framework are described. Capabilities of Munit like mocking message processors and outbound endpoints are outlined. Finally, resources credited for the information are provided.

1. Introduction to Unit Testing
for Mule Flows using
Munit(Java) - Part 1
January 6, 2015

2. What is a unit test?
A unit test is an automated piece of code that invokes a unit of work in the system and then checks a single assumption about
the behavior of that unit of work.
A unit of work is a single logical functional use case in the system that can be invoked by some public interface (in most cases). A unit of
work can span a single method, a whole class or multiple classes working together to achieve one single logical purpose that can be
verified.

3. What makes a good unit test?
1. Able to be fully automated
2. Has full control over all the pieces running (Use mocks or stubs to achieve this isolation when needed)
3. Can be run in any order if part of many other tests
4. Runs in memory (no DB or File access, for example)
5. Consistently returns the same result (You always run the same test, so no random numbers, for example.
save those for integration or range tests)
6. Runs fast
7. Tests a single logical concept in the system
8. Readable
9. Maintainable
10.Trustworthy (when you see its result, you don’t need to debug the code just to be sure)

4. Why do we need a Unit Test?
1. Tests Reduce Bugs in New Features
2. Tests Reduce Bugs in Existing Features
3. Tests Are Good Documentation
4. Tests Reduce the Cost of Change
5. Tests Improve Design
6. Tests Allow Refactoring
7. Tests Constrain Features
8. Tests Defend Against Other Programmers

5. Dependencies
Anypoint Studio (any Runtime)
● Junit
● Munit
● Hamcrest

6. What is JUnit?
JUnit is a simple framework to write repeatable tests. It is an instance of the
xUnit architecture for unit testing frameworks.

7. What is Munit?
MUnit is a Mule application testing framework that allows you to easily build automated tests for your
integrations and APIs. It provides a full suite of integration and unit test capabilities, and is fully
integrated with Maven and Surefire for integration with your continuous deployment environment.

8. Munit Capabilities
Create your Mule test by writing Mule code
Create your Mule test by writing Java code
Disable flow inbound endpoints
Disable endpoint connectors
Mock outbound endpoints
Mock message processors

9. Munit Capabilities
Verify message processor calls
Create not only unit tests but also integration tests in a local environment — MUnit allows you to start a local
FTP/SFTP, DB server or mail server
Call the Mule client from Mule code
Assert flow exceptions
Enable or disable particular tests
See assertion/error reports with Mule stack trace

10. Credits
http://artofunittesting.com/definition-of-a-unit-test/
http://junit.org/
https://docs.mulesoft.com/mule-user-guide/v/3.7/munit
http://www.onjava.com/pub/a/onjava/2003/04/02/javaxpckbk.html