---
title: Your first test
description: Use Fixture.Create to build anonymous arrange data in a simple unit test.
---

This page walks through a small unit test where AutoFixture replaces hand-written arrange values. You use `new Fixture()` directly inside the test method.

## Example scenario

You are testing `LineTotalCalculator.Calculate`, which returns `quantity × unitPrice`. The test should verify the line total matches that product. You need a quantity, a unit price, and a calculator instance for the arrange step, but the exact values do not matter.

## Example

```csharp
var fixture = new Fixture();
var quantity = fixture.Create<int>();
var unitPrice = fixture.Create<decimal>();
var sut = fixture.Create<LineTotalCalculator>();

var total = sut.Calculate(quantity, unitPrice);

Assert.Equal(quantity * unitPrice, total);
```

## How it works

- `new Fixture()` — creates a data generator local to this test
- `Create<int>()` and `Create<decimal>()` — anonymous operands (quantity and unit price)
- `Create<LineTotalCalculator>()` — builds the calculator (no manual `new` when the type has a simple constructor)
- `sut` — the system under test (SUT); the instance under test
- `Assert.Equal(quantity * unitPrice, total)` — expected value comes from the operands you arranged, not from re-running production code

Use `new Fixture()` when a single test needs one-off anonymous data. When many tests share the same customizations, consider a fixture factory or xUnit.net 3 [AutoData](/docs/integrations/xunit3).

## Example types

The test above uses this type:

```csharp
public class LineTotalCalculator
{
    public decimal Calculate(int quantity, decimal unitPrice) =>
        quantity * unitPrice;
}
```

## Next steps

- [Introduction](/docs/get-started/introduction)
- [Refactoring a test](/docs/get-started/refactoring-a-test)
- [Fixture and Create](/docs/fundamentals/fixture-and-create)