Mikado Method

Setting up test data for your first test takes a lot of time. That’s not going to help us to test our bugs in legacy code! Let’s try the Mikado Method to:

Present the Mikado Method

Mikado game sticks

Image Source

The Mikado Method is a technique to incrementally do large refactorings, alongside feature delivery.

You’ll find resource about the Mikado Method here or on your room walls.

Rapid Response Question

As a group, what are the top 5 most important things about the the Mikado Method?

Live code the beginning of the Mikado Graph here

To help you to get started, here is a demo of how to use the Mikado Method in our particular situation.

Video of the beginning of the solution

Video Screen Shots

Mikado Graph

Screen-shot of the Mikado Graph from the video

Mikado Graph

Code Snippets

Code of InvoiceTest from the video 
    @Test
    void Mikado_Method_Constraint_Applies_tax_rules_when_computing_total_amount() {
        Country usa = new Country("USA", Currency.US_DOLLAR, Language.ENGLISH);
        Invoice invoice = new Invoice("Joe", usa);
    }

DIY

Now that you have a better idea, grab a whiteboard, a marker, some post-its and start creating your own mikado graph to add a test.

Photo of a whiteboard, markers and post-its, the material needed to draw a Mikado Method

Image Source

Delete the tests

In real life, you would

  1. Fix the bugs
  2. Start the mikado method to setup your test data

So let’s Ignore or Comment-Out the previous tests!

Use Mikado Method to setup data for a test on Invoice

We’ll first focus on testing the Invoice (java | c++ | c# | kotlin | scala) class. It’s simpler and achievable given the time we have.

To solve this section, use the test entitled Mikado_Method_Constraint_Applies_tax_rules_when_computing_total_amount!

Write your test as if you could instantiate your objects, and start to draw your mikado graph.

Make sure your project keeps building all the time. Notice every time you have something useful.

Use Mikado Method to setup data for a test on Report Generator (advanced)

If you have the time, repeat the same exercise with the test on ReportGenerator (java c++ c# kotlin scala) class.

Mini-retro

Time for a mini-retro again.

Take a few minutes to discuss the good and the bad of this approach.

Then compare them to what people usually say in the Retrospectives Guide

Continue: