added object mother with fluent builder example

patterns/build.gradle

@@ -0,0 +1,22 @@
+buildscript {
+	repositories {
+		jcenter()
+	}
+}
+
+apply plugin: 'java'
+
+version = '0.0.1-SNAPSHOT'
+sourceCompatibility = 1.8
+
+repositories {
+	mavenLocal()
+	mavenCentral()
+}
+
+dependencies {
+	compileOnly 'org.projectlombok:lombok:1.18.2'
+	testCompile 'org.junit.jupiter:junit-jupiter-engine:5.0.1'
+	testCompile 'org.assertj:assertj-core:2.6.0'
+}
+

patterns/src/main/java/io/reflectoring/objectmother/Address.java

@@ -0,0 +1,19 @@
+package io.reflectoring.objectmother;
+
+import lombok.Builder;
+import lombok.Data;
+
+@Data
+@Builder
+class Address {
+
+	private String street;
+
+	private String houseNumber;
+
+	private String zipCode;
+
+	private String city;
+
+	private String country;
+}

patterns/src/main/java/io/reflectoring/objectmother/Invoice.java

@@ -0,0 +1,18 @@
+package io.reflectoring.objectmother;
+
+import java.util.List;
+
+import lombok.Builder;
+import lombok.Data;
+
+@Data
+@Builder
+class Invoice {
+
+	private long id;
+
+	private Address address;
+
+	private List<InvoiceItem> items;
+
+}

patterns/src/main/java/io/reflectoring/objectmother/InvoiceItem.java

@@ -0,0 +1,18 @@
+package io.reflectoring.objectmother;
+
+import lombok.Builder;
+import lombok.Data;
+
+@Data
+@Builder
+class InvoiceItem {
+
+	private long amount;
+
+	private long price;
+
+	private String productName;
+
+	private double taxFactor;
+
+}

patterns/src/test/java/io/reflectoring/objectmother/AddressMother.java

@@ -0,0 +1,19 @@
+package io.reflectoring.objectmother;
+
+class AddressMother {
+
+	static Address.AddressBuilder complete() {
+		return Address.builder()
+						.street("Hollywood Boulevard")
+						.houseNumber("4711")
+						.zipCode("90210")
+						.country("US")
+						.city("Los Angeles");
+	}
+
+	static Address.AddressBuilder abroad() {
+		return complete()
+						.country("DE");
+	}
+
+}

patterns/src/test/java/io/reflectoring/objectmother/InvoiceItemMother.java

@@ -0,0 +1,21 @@
+package io.reflectoring.objectmother;
+
+class InvoiceItemMother {
+
+	static InvoiceItem.InvoiceItemBuilder complete() {
+		return InvoiceItem.builder()
+						.amount(1)
+						.price(1234L)
+						.productName("The Hitchhiker's Guide to the Galaxy")
+						.taxFactor(0.19d);
+	}
+
+	static InvoiceItem.InvoiceItemBuilder withNegativePrice() {
+		return InvoiceItem.builder()
+						.amount(1)
+						.price(-1234L)
+						.productName("The Hitchhiker's Guide to the Galaxy")
+						.taxFactor(0.19d);
+	}
+
+}

patterns/src/test/java/io/reflectoring/objectmother/InvoiceMother.java

@@ -0,0 +1,28 @@
+package io.reflectoring.objectmother;
+
+import java.util.Collections;
+
+class InvoiceMother {
+
+	static Invoice.InvoiceBuilder complete() {
+		return Invoice.builder()
+						.id(42L)
+						.address(AddressMother.complete()
+										.build())
+						.items(Collections.singletonList(
+										InvoiceItemMother.complete()
+														.build()));
+	}
+
+	static Invoice.InvoiceBuilder refund() {
+		return Invoice.builder()
+						.id(42L)
+						.address(AddressMother.complete()
+										.build())
+						.items(Collections.singletonList(
+										InvoiceItemMother.withNegativePrice()
+														.build()));
+	}
+
+
+}

patterns/src/test/java/io/reflectoring/objectmother/ObjectMotherClient.java

@@ -0,0 +1,37 @@
+package io.reflectoring.objectmother;
+
+import org.junit.jupiter.api.Test;
+import static org.assertj.core.api.Assertions.*;
+
+class ObjectMotherClient {
+
+	@Test
+	void invoiceWithAbroadAddress() {
+		Invoice invoice = InvoiceMother.complete()
+						.address(AddressMother.abroad()
+										.build())
+						.build();
+		assertThat(invoice.getAddress().getCountry()).isEqualTo("DE");
+	}
+
+	@Test
+	void invoiceWithMissingHouseNumber() {
+		Invoice invoice = InvoiceMother.complete()
+						.address(AddressMother.complete()
+										.houseNumber(null)
+										.build())
+						.build();
+		assertThat(invoice.getAddress().getHouseNumber()).isNull();
+	}
+
+	@Test
+	void invoiceWithNegativeTotal() {
+		Invoice invoice = InvoiceMother.refund()
+						.build();
+		double sum = invoice.getItems().stream()
+						.mapToDouble(item -> item.getAmount() * item.getPrice())
+						.sum();
+		assertThat(sum).isNegative();
+	}
+
+}

settings.gradle

@@ -23,5 +23,7 @@ include 'logging'
 
 include 'junit:conditions'
 
+include 'patterns'
+