Building Test Data

Let’s try to improve the following:

Our tests contain a lot of duplication
Setting up data for our tests was long and painful

Present Test Data Builders

A child pilling up legos

Image Source

Test Data Builders are particularly handful to build test data. They should help us here.

You’ll find resource about Test Data Builders here or on your room walls.

Rapid Response Question

As a group, what are the top 5 most important things about the Test Data Builders?

Live code the beginning of the Test Data-Builders here

To help you to get started, here is a demo of how to use the Test Data-Builders in our particular situation.

Video Screen Shots

Code Snippets

Code Snippets of NovelTestDataBuilder from the video

NovelTestDataBuilder.java

  package com.murex.tbw.domain.book;
  
  import com.google.common.collect.Lists;
  import com.murex.tbw.domain.country.Language;
  
  public class NovelTestDataBuilder {
      private double price = 10;
  
      public static NovelTestDataBuilder aNovel() {
          return new NovelTestDataBuilder();
      }
  
      public NovelTestDataBuilder costing(double price) {
          this.price = price;
          return this;
      }
  
      public Novel build() {
          return new Novel("Test Data Builders for Dummies", price, null, Language.ENGLISH, Lists.newArrayList());
      }
  }

Code Snippets of InvoiceTest from the video

InvoiceTest.java

  package com.murex.tbw.purchase;
  
  import com.murex.tbw.domain.book.NovelTestDataBuilder;
  import org.junit.jupiter.api.Assertions;
  import org.junit.jupiter.api.Test;
  
  import static org.junit.jupiter.api.Assertions.*;

  class InvoiceTest {
      @Test
      void Test_Data_Builders_Constraint_Applies_tax_rules_when_computing_total_amount() {
          Invoice invoice = InvoiceTestDataBuilder.anInvoice()
                  .from(USA)
                  .with(PurchasedBookTestDataBuilder.aPurchasedBook()
                          .of(NovelTestDataBuilder.aNovel()
                                  .costing(50.0)
                                  .build())
                          .build())
                  .build();
          Assertions.assertEquals(50 * 1.15 * 0.98, invoice.computeTotalAmount());
      }
  }

DIY

Now that you know everything about Test Data Builders, try to use them to improve your tests.

Delete the tests

In real life, you would

Fix the bugs
Use test data-builders to instantiate your test data.

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

Use Test-Data-Builders to setup the 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 Test_Data_Builders_Constraint_Applies_tax_rules_when_computing_total_amount!

Use the test data-builder to instantiate your objects in the test.

Use Test-Data-Builders to setup the data for a test on Report Generator (advanced)

If you have the time, repeat the same exercise with the test on ReportGenerator (java

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: