Quick Start Guide
What You’ll Learn
- Core methods for customizing test objects with Fixture Monkey
- Basic approaches to customize simple and complex objects
- Solutions to the most common problems beginners face
5-Minute Quick Start
This section covers only the essential information needed to get started with Fixture Monkey.
4 Key Methods You Must Know
If you’re short on time, here’s what you need to know right now:
// 1. Create FixtureMonkey instance
FixtureMonkey fixtureMonkey = FixtureMonkey.create();
// 2. Create a product with specific property values
Product product = fixtureMonkey.giveMeBuilder(Product.class)
.set("name", "Smartphone") // Set property
.set("price", new BigDecimal(499)) // Set another property
.sample(); // Create the actual object
// 3. Create an order with a list of products
Order order = fixtureMonkey.giveMeBuilder(Order.class)
.size("products", 2) // Set list size to 2
.set("products[0].name", "Laptop") // Customize list element
.sample();// 1. Create FixtureMonkey instance
val fixtureMonkey = FixtureMonkey.create()
// 2. Create a product with specific property values
val product = fixtureMonkey.giveMeBuilder<Product>()
.setExp(Product::name, "Smartphone") // Set property
.setExp(Product::price, BigDecimal(499)) // Set another property
.sample() // Create the actual object
// 3. Create an order with a list of products
val order = fixtureMonkey.giveMeBuilder<Order>()
.sizeExp(Order::products, 2) // Set list size to 2
.set("products[0].name", "Laptop") // Customize list element
.sample()Visual Overview
Here’s a simple flowchart showing the process of customizing objects with Fixture Monkey:
Prerequisites
This guide assumes:
- You’ve already added Fixture Monkey to your project
- You know how to create a basic FixtureMonkey instance
If you haven’t set up Fixture Monkey yet, refer to the Getting Started section first.
Basic Customization Methods
This section introduces the most fundamental customization methods you’ll use daily.
Setting Property Values
The most basic way to customize an object is to set specific property values:
Product product = fixtureMonkey.giveMeBuilder(Product.class)
.set("name", "Smartphone")
.set("price", new BigDecimal("499.99"))
.set("available", true)
.sample();val product = fixtureMonkey.giveMeBuilder<Product>()
.setExp(Product::name, "Smartphone")
.setExp(Product::price, BigDecimal("499.99"))
.setExp(Product::available, true)
.sample()Setting Null Values
When you need to test with null values:
Product nullNameProduct = fixtureMonkey.giveMeBuilder(Product.class)
.setNull("name") // Set name to null
.sample();val nullNameProduct = fixtureMonkey.giveMeBuilder<Product>()
.setNullExp(Product::name) // Set name to null
.sample()Working with Collections
The most important thing when working with collections is to set the size first:
// Create an order with 2 products
Order orderWith2Products = fixtureMonkey.giveMeBuilder(Order.class)
.size("products", 2) // Set size first
.set("products[0].name", "Laptop") // Then customize elements
.sample();// Create an order with 2 products
val orderWith2Products = fixtureMonkey.giveMeBuilder<Order>()
.sizeExp(Order::products, 2) // Set size first
.set("products[0].name", "Laptop") // Then customize elements
.sample()For more advanced collection customization, check the Path Expressions document.
Customizing Nested Objects
You can access nested properties using dot notation:
// Create a customer with an address
Customer customer = fixtureMonkey.giveMeBuilder(Customer.class)
.set("name", "John Doe")
.set("address.street", "123 Main Street") // Nested property
.set("address.city", "New York") // Nested property
.sample();// Create a customer with an address
val customer = fixtureMonkey.giveMeBuilder<Customer>()
.setExp(Customer::name, "John Doe")
.set("address.street", "123 Main Street") // Nested property
.set("address.city", "New York") // Nested property
.sample()For more complex nested object customization, check the InnerSpec guide.
Frequently Asked Questions
The most common issues beginners face.
Why is my collection empty when I tried to customize an element?
The most common mistake is not setting the collection size first:
// Wrong way - collection might be empty
Order orderWrong = fixtureMonkey.giveMeBuilder(Order.class)
.set("products[0].name", "Laptop") // This might not work!
.sample();
// Correct way - set size first
Order orderCorrect = fixtureMonkey.giveMeBuilder(Order.class)
.size("products", 1) // Set size first!
.set("products[0].name", "Laptop") // Now this works
.sample();// Wrong way - collection might be empty
val orderWrong = fixtureMonkey.giveMeBuilder<Order>()
.set("products[0].name", "Laptop") // This might not work!
.sample()
// Correct way - set size first
val orderCorrect = fixtureMonkey.giveMeBuilder<Order>()
.sizeExp(Order::products, 1) // Set size first!
.set("products[0].name", "Laptop") // Now this works
.sample()Why do I get null values when I didn’t set them to null?
By default, Fixture Monkey may generate null values for some properties. To ensure values are not null:
Product nonNullProduct = fixtureMonkey.giveMeBuilder(Product.class)
.setNotNull("name") // Ensure name is not null
.setNotNull("price") // Ensure price is not null
.sample();val nonNullProduct = fixtureMonkey.giveMeBuilder<Product>()
.setNotNullExp(Product::name) // Ensure name is not null
.setNotNullExp(Product::price) // Ensure price is not null
.sample()Next Steps
Now that you’ve learned the basics, explore these topics for more advanced usage:
- Path Expressions - Accessing and customizing nested properties
- Customization APIs - Complete list of customization methods
- Testing Interfaces - How to work with interfaces
- InnerSpec - Advanced customization for complex objects
- Arbitrary - Generating test data with specific constraints