Test Data Builder Generator

Generates Test Data Builder and Object Mother patterns for test data creation.

Patterns

Test Data Builder

Fluent interface for constructing test objects with customizable properties.

When to use:

• Complex objects with many properties
• Need to customize specific properties per test
• Want to express test intent clearly

Object Mother

Factory methods returning pre-configured objects for common scenarios.

When to use:

• Standard test fixtures (default user, pending order)
• Shared across many tests
• Named scenarios (premium customer, expired subscription)

Builder Template

<?php

declare(strict_types=1);

namespace Tests\Builder;

use {FullyQualifiedClassName};

final class {ClassName}Builder
{
    private {IdType} $id;
    private {Property1Type} ${property1};
    private {Property2Type} ${property2};
    // ... other properties

    private function __construct()
    {
        // Sensible defaults
        $this->id = {IdType}::generate();
        $this->{property1} = {default1};
        $this->{property2} = {default2};
    }

    public static function a{ClassName}(): self
    {
        return new self();
    }

    public static function an{ClassName}(): self
    {
        return new self();
    }

    public function withId({IdType} $id): self
    {
        $clone = clone $this;
        $clone->id = $id;
        return $clone;
    }

    public function with{Property1}({Property1Type} ${property1}): self
    {
        $clone = clone $this;
        $clone->{property1} = ${property1};
        return $clone;
    }

    public function with{Property2}({Property2Type} ${property2}): self
    {
        $clone = clone $this;
        $clone->{property2} = ${property2};
        return $clone;
    }

    public function build(): {ClassName}
    {
        return new {ClassName}(
            $this->id,
            $this->{property1},
            $this->{property2}
        );
    }
}

Object Mother Template

<?php

declare(strict_types=1);

namespace Tests\Mother;

use {FullyQualifiedClassName};

final class {ClassName}Mother
{
    public static function default(): {ClassName}
    {
        return {ClassName}Builder::a{ClassName}()->build();
    }

    public static function {scenario1}(): {ClassName}
    {
        return {ClassName}Builder::a{ClassName}()
            ->with{Property}({value})
            ->build();
    }

    public static function {scenario2}(): {ClassName}
    {
        return {ClassName}Builder::a{ClassName}()
            ->with{Property1}({value1})
            ->with{Property2}({value2})
            ->build();
    }
}

Complete Example: Order

OrderBuilder

<?php

declare(strict_types=1);

namespace Tests\Builder;

use App\Domain\Order\Order;
use App\Domain\Order\OrderId;
use App\Domain\Order\OrderItem;
use App\Domain\Order\OrderStatus;
use App\Domain\Customer\CustomerId;
use App\Domain\Shared\Money;
use DateTimeImmutable;

final class OrderBuilder
{
    private OrderId $id;
    private CustomerId $customerId;
    /** @var list<OrderItem> */
    private array $items = [];
    private OrderStatus $status;
    private DateTimeImmutable $createdAt;

    private function __construct()
    {
        $this->id = OrderId::generate();
        $this->customerId = CustomerId::generate();
        $this->status = OrderStatus::Pending;
        $this->createdAt = new DateTimeImmutable();
    }

    public static function anOrder(): self
    {
        return new self();
    }

    public function withId(OrderId $id): self
    {
        $clone = clone $this;
        $clone->id = $id;
        return $clone;
    }

    public function forCustomer(CustomerId $customerId): self
    {
        $clone = clone $this;
        $clone->customerId = $customerId;
        return $clone;
    }

    public function withItem(Product $product, int $quantity = 1): self
    {
        $clone = clone $this;
        $clone->items[] = new OrderItem($product, $quantity);
        return $clone;
    }

    public function withItems(array $items): self
    {
        $clone = clone $this;
        $clone->items = $items;
        return $clone;
    }

    public function withTotal(Money $total): self
    {
        $clone = clone $this;
        $clone->items = [
            new OrderItem(ProductMother::withPrice($total), 1),
        ];
        return $clone;
    }

    public function pending(): self
    {
        $clone = clone $this;
        $clone->status = OrderStatus::Pending;
        return $clone;
    }

    public function confirmed(): self
    {
        $clone = clone $this;
        $clone->status = OrderStatus::Confirmed;
        // Add item if empty (can't confirm empty order)
        if (empty($clone->items)) {
            $clone->items[] = new OrderItem(ProductMother::book(), 1);
        }
        return $clone;
    }

    public function shipped(): self
    {
        $clone = clone $this;
        $clone->status = OrderStatus::Shipped;
        if (empty($clone->items)) {
            $clone->items[] = new OrderItem(ProductMother::book(), 1);
        }
        return $clone;
    }

    public function cancelled(): self
    {
        $clone = clone $this;
        $clone->status = OrderStatus::Cancelled;
        return $clone;
    }

    public function createdAt(DateTimeImmutable $createdAt): self
    {
        $clone = clone $this;
        $clone->createdAt = $createdAt;
        return $clone;
    }

    public function createdDaysAgo(int $days): self
    {
        return $this->createdAt(
            new DateTimeImmutable("-{$days} days")
        );
    }

    public function build(): Order
    {
        $order = new Order($this->id, $this->customerId, $this->createdAt);

        foreach ($this->items as $item) {
            $order->addItem($item->product(), $item->quantity());
        }

        // Apply status transitions
        if ($this->status === OrderStatus::Confirmed) {
            $order->confirm();
        } elseif ($this->status === OrderStatus::Shipped) {
            $order->confirm();
            $order->ship();
        } elseif ($this->status === OrderStatus::Cancelled) {
            $order->cancel();
        }

        return $order;
    }
}

OrderMother

<?php

declare(strict_types=1);

namespace Tests\Mother;

use App\Domain\Order\Order;
use App\Domain\Customer\CustomerId;
use App\Domain\Shared\Money;
use Tests\Builder\OrderBuilder;

final class OrderMother
{
    public static function pending(): Order
    {
        return OrderBuilder::anOrder()->pending()->build();
    }

    public static function confirmed(): Order
    {
        return OrderBuilder::anOrder()->confirmed()->build();
    }

    public static function shipped(): Order
    {
        return OrderBuilder::anOrder()->shipped()->build();
    }

    public static function cancelled(): Order
    {
        return OrderBuilder::anOrder()->cancelled()->build();
    }

    public static function forCustomer(CustomerId $customerId): Order
    {
        return OrderBuilder::anOrder()
            ->forCustomer($customerId)
            ->build();
    }

    public static function withTotal(Money $total): Order
    {
        return OrderBuilder::anOrder()
            ->withTotal($total)
            ->build();
    }

    public static function empty(): Order
    {
        return OrderBuilder::anOrder()->build();
    }

    public static function withItems(array $items): Order
    {
        return OrderBuilder::anOrder()
            ->withItems($items)
            ->build();
    }

    public static function expired(): Order
    {
        return OrderBuilder::anOrder()
            ->pending()
            ->createdDaysAgo(31)
            ->build();
    }
}

Value Object Builders

<?php

declare(strict_types=1);

namespace Tests\Builder;

use App\Domain\Shared\Money;

final class MoneyBuilder
{
    private int $amount;
    private string $currency;

    private function __construct()
    {
        $this->amount = 1000;
        $this->currency = 'EUR';
    }

    public static function money(): self
    {
        return new self();
    }

    public function withAmount(int $amount): self
    {
        $clone = clone $this;
        $clone->amount = $amount;
        return $clone;
    }

    public function inEUR(): self
    {
        $clone = clone $this;
        $clone->currency = 'EUR';
        return $clone;
    }

    public function inUSD(): self
    {
        $clone = clone $this;
        $clone->currency = 'USD';
        return $clone;
    }

    public function zero(): self
    {
        return $this->withAmount(0);
    }

    public function build(): Money
    {
        return new Money($this->amount, $this->currency);
    }
}

final class MoneyMother
{
    public static function eur(int $amount): Money
    {
        return Money::EUR($amount);
    }

    public static function usd(int $amount): Money
    {
        return Money::USD($amount);
    }

    public static function zero(): Money
    {
        return Money::EUR(0);
    }

    public static function oneHundred(): Money
    {
        return Money::EUR(10000); // cents
    }
}

Usage in Tests

// Builder - custom configuration
$order = OrderBuilder::anOrder()
    ->forCustomer($customerId)
    ->withItem($book, 2)
    ->withItem($pen, 5)
    ->confirmed()
    ->createdDaysAgo(7)
    ->build();

// Mother - common scenarios
$pendingOrder = OrderMother::pending();
$confirmedOrder = OrderMother::confirmed();
$expiredOrder = OrderMother::expired();
$customerOrder = OrderMother::forCustomer($customerId);

Generation Instructions

1. Analyze the target class:

   • Constructor parameters
   • Required vs optional properties
   • Value objects used
   • State transitions (for entities)

2. Determine sensible defaults:

   • Generate IDs automatically
   • Use common/valid values
   • Consider relationships

3. Create Builder with:

   • Private constructor with defaults
   • Static factory method (aOrder, anEmail)
   • with* methods for each property
   • Immutable (clone in each method)
   • build() method

4. Create Mother with:

   • default() method
   • Named scenarios (pending, confirmed, premium)
   • Parameterized methods (forCustomer, withTotal)

5. File placement:

   • Builders: tests/Builder/{ClassName}Builder.php
   • Mothers: tests/Mother/{ClassName}Mother.php

Best Practices

1. Sensible defaults — Tests should work without customization
2. Fluent interface — Chain method calls
3. Immutable builders — Clone in each with* method
4. Expressive names — pending() not withStatus(pending)
5. Composition — Builders can use other Mothers/Builders
6. Single Responsibility — One builder per aggregate/entity