Merge branch 'master' of https://github.com/JonCook/tutorials

ddd/README.md

@@ -0,0 +1,9 @@
+## Domain-driven Design (DDD)
+
+This module contains articles about Domain-driven Design (DDD)
+
+### Relevant articles
+
+- [Persisting DDD Aggregates](https://www.baeldung.com/spring-persisting-ddd-aggregates)
+- [Double Dispatch in DDD](https://www.baeldung.com/ddd-double-dispatch)
+- [DDD Aggregates and @DomainEvents](https://www.baeldung.com/spring-data-ddd)

ddd/pom.xml

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+<project xmlns="http://maven.apache.org/POM/4.0.0" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+    <groupId>com.baeldung.ddd</groupId>
+    <artifactId>ddd</artifactId>
+    <name>ddd</name>
+    <packaging>jar</packaging>
+    <description>DDD series examples</description>
+
+    <parent>
+        <artifactId>parent-boot-2</artifactId>
+        <groupId>com.baeldung</groupId>
+        <version>0.0.1-SNAPSHOT</version>
+        <relativePath>../parent-boot-2</relativePath>
+    </parent>
+
+    <dependencies>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-mongodb</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-api</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.junit.jupiter</groupId>
+            <artifactId>junit-jupiter-engine</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <!-- JUnit platform launcher -->
+        <!-- To be able to run tests from IDE directly -->
+        <dependency>
+            <groupId>org.junit.platform</groupId>
+            <artifactId>junit-platform-launcher</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.joda</groupId>
+            <artifactId>joda-money</artifactId>
+            <version>${joda-money.version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-data-jpa</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>com.h2database</groupId>
+            <artifactId>h2</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>mysql</groupId>
+            <artifactId>mysql-connector-java</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.postgresql</groupId>
+            <artifactId>postgresql</artifactId>
+            <scope>runtime</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-devtools</artifactId>
+            <optional>true</optional>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-web</artifactId>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework.boot</groupId>
+            <artifactId>spring-boot-starter-test</artifactId>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>de.flapdoodle.embed</groupId>
+            <artifactId>de.flapdoodle.embed.mongo</artifactId>
+            <scope>test</scope>
+        </dependency>
+    </dependencies>
+
+    <properties>
+        <joda-money.version>1.0.1</joda-money.version>
+    </properties>
+	
+</project>

ddd/src/main/java/com/baeldung/ddd/PersistingDddAggregatesApplication.java

@@ -0,0 +1,12 @@
+package com.baeldung.ddd;
+
+import org.springframework.boot.SpringApplication;
+import org.springframework.boot.autoconfigure.SpringBootApplication;
+
+@SpringBootApplication
+public class PersistingDddAggregatesApplication {
+
+	public static void main(String[] args) {
+		SpringApplication.run(PersistingDddAggregatesApplication.class, args);
+	}
+}

ddd/src/main/java/com/baeldung/ddd/order/Order.java

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+package com.baeldung.ddd.order;
+
+import java.util.ArrayList;
+import java.util.List;
+
+import org.joda.money.Money;
+
+public class Order {
+    private final List<OrderLine> orderLines;
+    private Money totalCost;
+
+    public Order(List<OrderLine> orderLines) {
+        checkNotNull(orderLines);
+        if (orderLines.isEmpty()) {
+            throw new IllegalArgumentException("Order must have at least one order line item");
+        }
+        this.orderLines = new ArrayList<>(orderLines);
+        totalCost = calculateTotalCost();
+    }
+
+    public void addLineItem(OrderLine orderLine) {
+        checkNotNull(orderLine);
+        orderLines.add(orderLine);
+        totalCost = totalCost.plus(orderLine.cost());
+    }
+
+    public List<OrderLine> getOrderLines() {
+        return new ArrayList<>(orderLines);
+    }
+
+    public void removeLineItem(int line) {
+        OrderLine removedLine = orderLines.remove(line);
+        totalCost = totalCost.minus(removedLine.cost());
+    }
+
+    public Money totalCost() {
+        return totalCost;
+    }
+
+    private Money calculateTotalCost() {
+        return orderLines.stream()
+            .map(OrderLine::cost)
+            .reduce(Money::plus)
+            .get();
+    }
+
+    private static void checkNotNull(Object par) {
+        if (par == null) {
+            throw new NullPointerException("Parameter cannot be null");
+        }
+    }
+}

ddd/src/main/java/com/baeldung/ddd/order/OrderLine.java

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+package com.baeldung.ddd.order;
+
+import org.joda.money.Money;
+
+public class OrderLine {
+    private final Product product;
+    private final int quantity;
+
+    public OrderLine(Product product, int quantity) {
+        super();
+        this.product = product;
+        this.quantity = quantity;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        OrderLine other = (OrderLine) obj;
+        if (product == null) {
+            if (other.product != null) {
+                return false;
+            }
+        } else if (!product.equals(other.product)) {
+            return false;
+        }
+        if (quantity != other.quantity) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((product == null) ? 0 : product.hashCode());
+        result = prime * result + quantity;
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return "OrderLine [product=" + product + ", quantity=" + quantity + "]";
+    }
+
+    Money cost() {
+        return product.getPrice()
+            .multipliedBy(quantity);
+    }
+
+    Product getProduct() {
+        return product;
+    }
+
+    int getQuantity() {
+        return quantity;
+    }
+
+}

ddd/src/main/java/com/baeldung/ddd/order/Product.java

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+package com.baeldung.ddd.order;
+
+import org.joda.money.Money;
+
+public class Product {
+    private final Money price;
+
+    public Product(Money price) {
+        super();
+        this.price = price;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        Product other = (Product) obj;
+        if (price == null) {
+            if (other.price != null) {
+                return false;
+            }
+        } else if (!price.equals(other.price)) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((price == null) ? 0 : price.hashCode());
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return "Product [price=" + price + "]";
+    }
+
+    Money getPrice() {
+        return price;
+    }
+
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/AmountBasedDiscountPolicy.java

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+package com.baeldung.ddd.order.doubledispatch;
+
+import org.joda.money.CurrencyUnit;
+import org.joda.money.Money;
+
+public class AmountBasedDiscountPolicy implements DiscountPolicy {
+    @Override
+    public double discount(Order order) {
+        if (order.totalCost()
+            .isGreaterThan(Money.of(CurrencyUnit.USD, 500.00))) {
+            return 0.10;
+        } else
+            return 0;
+    }
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/DiscountPolicy.java

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+package com.baeldung.ddd.order.doubledispatch;
+
+public interface DiscountPolicy {
+    double discount(Order order);
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/FlatDiscountPolicy.java

@@ -0,0 +1,8 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+public class FlatDiscountPolicy implements DiscountPolicy {
+    @Override
+    public double discount(Order order) {
+        return 0.01;
+    }
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/Order.java

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+package com.baeldung.ddd.order.doubledispatch;
+
+import java.math.RoundingMode;
+import java.util.List;
+
+import org.joda.money.Money;
+
+import com.baeldung.ddd.order.OrderLine;
+import com.baeldung.ddd.order.doubledispatch.visitor.OrderVisitor;
+import com.baeldung.ddd.order.doubledispatch.visitor.Visitable;
+
+public class Order extends com.baeldung.ddd.order.Order implements Visitable<OrderVisitor> {
+    public Order(List<OrderLine> orderLines) {
+        super(orderLines);        
+    }
+
+    public Money totalCost(SpecialDiscountPolicy discountPolicy) {
+        return totalCost().multipliedBy(1 - applyDiscountPolicy(discountPolicy), RoundingMode.HALF_UP);
+    }
+
+    protected double applyDiscountPolicy(SpecialDiscountPolicy discountPolicy) {
+        return discountPolicy.discount(this);
+    }
+    
+    @Override
+    public void accept(OrderVisitor visitor) {
+        visitor.visit(this);        
+    }
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/SpecialDiscountPolicy.java

@@ -0,0 +1,5 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+public interface SpecialDiscountPolicy extends DiscountPolicy {
+    double discount(SpecialOrder order);
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/SpecialOrder.java

@@ -0,0 +1,36 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import java.util.List;
+
+import com.baeldung.ddd.order.OrderLine;
+import com.baeldung.ddd.order.doubledispatch.visitor.OrderVisitor;
+
+public class SpecialOrder extends Order {
+
+    private boolean eligibleForExtraDiscount;
+
+    public SpecialOrder(List<OrderLine> orderLines) {
+        super(orderLines);
+        this.eligibleForExtraDiscount = false;
+    }
+
+    public SpecialOrder(List<OrderLine> orderLines, boolean eligibleForSpecialDiscount) {
+        super(orderLines);
+        this.eligibleForExtraDiscount = eligibleForSpecialDiscount;
+    }
+
+    public boolean isEligibleForExtraDiscount() {
+        return eligibleForExtraDiscount;
+    }
+
+    @Override
+    protected double applyDiscountPolicy(SpecialDiscountPolicy discountPolicy) {
+        return discountPolicy.discount(this);
+    }
+
+    @Override
+    public void accept(OrderVisitor visitor) {
+        visitor.visit(this);
+    }
+
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/visitor/HtmlOrderViewCreator.java

@@ -0,0 +1,24 @@
+package com.baeldung.ddd.order.doubledispatch.visitor;
+
+import com.baeldung.ddd.order.doubledispatch.Order;
+import com.baeldung.ddd.order.doubledispatch.SpecialOrder;
+
+public class HtmlOrderViewCreator implements OrderVisitor {
+    
+    private String html;
+    
+    public String getHtml() {
+        return html;
+    }
+
+    @Override
+    public void visit(Order order) {
+        html = String.format("<p>Regular order total cost: %s</p>", order.totalCost());
+    }
+
+    @Override
+    public void visit(SpecialOrder order) {
+        html = String.format("<h1>Special Order</h1><p>total cost: %s</p>", order.totalCost());
+    }
+
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/visitor/OrderVisitor.java

@@ -0,0 +1,9 @@
+package com.baeldung.ddd.order.doubledispatch.visitor;
+
+import com.baeldung.ddd.order.doubledispatch.Order;
+import com.baeldung.ddd.order.doubledispatch.SpecialOrder;
+
+public interface OrderVisitor {
+    void visit(Order order);
+    void visit(SpecialOrder order);
+}

ddd/src/main/java/com/baeldung/ddd/order/doubledispatch/visitor/Visitable.java

@@ -0,0 +1,5 @@
+package com.baeldung.ddd.order.doubledispatch.visitor;
+
+public interface Visitable<V> {
+    void accept(V visitor);
+}

ddd/src/main/java/com/baeldung/ddd/order/jpa/JpaOrder.java

@@ -0,0 +1,111 @@
+package com.baeldung.ddd.order.jpa;
+
+import java.math.BigDecimal;
+import java.util.ArrayList;
+import java.util.List;
+
+import javax.persistence.ElementCollection;
+import javax.persistence.Entity;
+import javax.persistence.FetchType;
+import javax.persistence.GeneratedValue;
+import javax.persistence.Id;
+import javax.persistence.Table;
+
+@Entity
+@Table(name = "order_table")
+class JpaOrder {
+    private String currencyUnit;
+    @Id
+    @GeneratedValue
+    private Long id;
+    @ElementCollection(fetch = FetchType.EAGER)
+    private final List<JpaOrderLine> orderLines;
+    private BigDecimal totalCost;
+
+    JpaOrder() {
+        totalCost = null;
+        orderLines = new ArrayList<>();
+    }
+
+    JpaOrder(List<JpaOrderLine> orderLines) {
+        checkNotNull(orderLines);
+        if (orderLines.isEmpty()) {
+            throw new IllegalArgumentException("Order must have at least one order line item");
+        }
+        this.orderLines = new ArrayList<>(orderLines);
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        JpaOrder other = (JpaOrder) obj;
+        if (id == null) {
+            if (other.id != null) {
+                return false;
+            }
+        } else if (!id.equals(other.id)) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((id == null) ? 0 : id.hashCode());
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return "JpaOrder [currencyUnit=" + currencyUnit + ", id=" + id + ", orderLines=" + orderLines + ", totalCost=" + totalCost + "]";
+    }
+
+    void addLineItem(JpaOrderLine orderLine) {
+        checkNotNull(orderLine);
+        orderLines.add(orderLine);
+    }
+
+    String getCurrencyUnit() {
+        return currencyUnit;
+    }
+
+    Long getId() {
+        return id;
+    }
+
+    List<JpaOrderLine> getOrderLines() {
+        return new ArrayList<>(orderLines);
+    }
+
+    BigDecimal getTotalCost() {
+        return totalCost;
+    }
+
+    void removeLineItem(int line) {
+        orderLines.remove(line);
+    }
+
+    void setCurrencyUnit(String currencyUnit) {
+        this.currencyUnit = currencyUnit;
+    }
+
+    void setTotalCost(BigDecimal totalCost) {
+        this.totalCost = totalCost;
+    }
+
+    private static void checkNotNull(Object par) {
+        if (par == null) {
+            throw new NullPointerException("Parameter cannot be null");
+        }
+    }
+}

ddd/src/main/java/com/baeldung/ddd/order/jpa/JpaOrderLine.java

@@ -0,0 +1,70 @@
+package com.baeldung.ddd.order.jpa;
+
+import javax.persistence.Embeddable;
+import javax.persistence.Embedded;
+
+@Embeddable
+class JpaOrderLine {
+    @Embedded
+    private final JpaProduct product;
+    private final int quantity;
+
+    JpaOrderLine() {
+        quantity = 0;
+        product = null;
+    }
+
+    JpaOrderLine(JpaProduct product, int quantity) {
+        super();
+        this.product = product;
+        this.quantity = quantity;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        JpaOrderLine other = (JpaOrderLine) obj;
+        if (product == null) {
+            if (other.product != null) {
+                return false;
+            }
+        } else if (!product.equals(other.product)) {
+            return false;
+        }
+        if (quantity != other.quantity) {
+            return false;
+        }
+        return true;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((product == null) ? 0 : product.hashCode());
+        result = prime * result + quantity;
+        return result;
+    }
+
+    @Override
+    public String toString() {
+        return "JpaOrderLine [product=" + product + ", quantity=" + quantity + "]";
+    }
+
+    JpaProduct getProduct() {
+        return product;
+    }
+
+    int getQuantity() {
+        return quantity;
+    }
+
+}

ddd/src/main/java/com/baeldung/ddd/order/jpa/JpaOrderRepository.java

@@ -0,0 +1,7 @@
+package com.baeldung.ddd.order.jpa;
+
+import org.springframework.data.jpa.repository.JpaRepository;
+
+public interface JpaOrderRepository extends JpaRepository<JpaOrder, Long> {
+
+}

ddd/src/main/java/com/baeldung/ddd/order/jpa/JpaProduct.java

@@ -0,0 +1,79 @@
+package com.baeldung.ddd.order.jpa;
+
+import java.math.BigDecimal;
+
+import javax.persistence.Embeddable;
+
+@Embeddable
+class JpaProduct {
+    private String currencyUnit;
+    private BigDecimal price;
+
+    public JpaProduct() {
+    }
+
+    public JpaProduct(BigDecimal price, String currencyUnit) {
+        super();
+        this.price = price;
+        this.currencyUnit = currencyUnit;
+    }
+
+    @Override
+    public boolean equals(Object obj) {
+        if (this == obj) {
+            return true;
+        }
+        if (obj == null) {
+            return false;
+        }
+        if (getClass() != obj.getClass()) {
+            return false;
+        }
+        JpaProduct other = (JpaProduct) obj;
+        if (currencyUnit == null) {
+            if (other.currencyUnit != null) {
+                return false;
+            }
+        } else if (!currencyUnit.equals(other.currencyUnit)) {
+            return false;
+        }
+        if (price == null) {
+            if (other.price != null) {
+                return false;
+            }
+        } else if (!price.equals(other.price)) {
+            return false;
+        }
+        return true;
+    }
+
+    public String getCurrencyUnit() {
+        return currencyUnit;
+    }
+
+    public BigDecimal getPrice() {
+        return price;
+    }
+
+    @Override
+    public int hashCode() {
+        final int prime = 31;
+        int result = 1;
+        result = prime * result + ((currencyUnit == null) ? 0 : currencyUnit.hashCode());
+        result = prime * result + ((price == null) ? 0 : price.hashCode());
+        return result;
+    }
+
+    public void setCurrencyUnit(String currencyUnit) {
+        this.currencyUnit = currencyUnit;
+    }
+
+    public void setPrice(BigDecimal price) {
+        this.price = price;
+    }
+
+    @Override
+    public String toString() {
+        return "JpaProduct [currencyUnit=" + currencyUnit + ", price=" + price + "]";
+    }
+}

ddd/src/main/java/com/baeldung/ddd/order/mongo/OrderMongoRepository.java

@@ -0,0 +1,9 @@
+package com.baeldung.ddd.order.mongo;
+
+import org.springframework.data.mongodb.repository.MongoRepository;
+
+import com.baeldung.ddd.order.Order;
+
+public interface OrderMongoRepository extends MongoRepository<Order, String> {
+
+}

ddd/src/test/java/com/baeldung/ddd/order/OrderFixtureUtils.java

@@ -0,0 +1,17 @@
+package com.baeldung.ddd.order;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.joda.money.CurrencyUnit;
+import org.joda.money.Money;
+
+public class OrderFixtureUtils {
+    public static List<OrderLine> anyOrderLines() {
+        return Arrays.asList(new OrderLine(new Product(Money.of(CurrencyUnit.USD, 100)), 1));
+    }
+
+    public static List<OrderLine> orderLineItemsWorthNDollars(int totalCost) {
+        return Arrays.asList(new OrderLine(new Product(Money.of(CurrencyUnit.USD, totalCost)), 1));
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/OrderUnitTest.java

@@ -0,0 +1,70 @@
+package com.baeldung.ddd.order;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.assertj.core.api.Assertions.catchThrowable;
+
+import java.util.ArrayList;
+import java.util.Arrays;
+
+import org.joda.money.CurrencyUnit;
+import org.joda.money.Money;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+class OrderUnitTest {
+    @DisplayName("given order with two items, when calculate total cost, then sum is returned")
+    @Test
+    void test0() throws Exception {
+        // given
+        OrderLine ol0 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 10.00)), 2);
+        OrderLine ol1 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 5.00)), 10);
+        Order order = new Order(Arrays.asList(ol0, ol1));
+
+        // when
+        Money totalCost = order.totalCost();
+
+        // then
+        assertThat(totalCost).isEqualTo(Money.of(CurrencyUnit.USD, 70.00));
+    }
+
+    @DisplayName("when create order without line items, then exception is thrown")
+    @Test
+    void test1() throws Exception {
+        // when
+        Throwable throwable = catchThrowable(() -> new Order(new ArrayList<>()));
+
+        // then
+        assertThat(throwable).isInstanceOf(IllegalArgumentException.class);
+    }
+
+    @DisplayName("given order with two line items, when add another line item, then total cost is updated")
+    @Test
+    void test2() throws Exception {
+        // given
+        OrderLine ol0 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 10.00)), 1);
+        OrderLine ol1 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 5.00)), 1);
+        Order order = new Order(Arrays.asList(ol0, ol1));
+
+        // when
+        order.addLineItem(new OrderLine(new Product(Money.of(CurrencyUnit.USD, 20.00)), 2));
+
+        // then
+        assertThat(order.totalCost()).isEqualTo(Money.of(CurrencyUnit.USD, 55));
+    }
+
+    @DisplayName("given order with three line items, when remove item, then total cost is updated")
+    @Test
+    void test3() throws Exception {
+        // given
+        OrderLine ol0 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 10.00)), 1);
+        OrderLine ol1 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 20.00)), 1);
+        OrderLine ol2 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 30.00)), 1);
+        Order order = new Order(Arrays.asList(ol0, ol1, ol2));
+
+        // when
+        order.removeLineItem(1);
+
+        // then
+        assertThat(order.totalCost()).isEqualTo(Money.of(CurrencyUnit.USD, 40.00));
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/doubledispatch/DoubleDispatchDiscountPolicyUnitTest.java

@@ -0,0 +1,77 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.joda.money.CurrencyUnit;
+import org.joda.money.Money;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.ddd.order.OrderFixtureUtils;
+
+public class DoubleDispatchDiscountPolicyUnitTest {
+    // @formatter:off
+    @DisplayName(
+        "given regular order with items worth $100 total, " +
+        "when apply 10% discount policy, " +
+        "then cost after discount is $90"
+        )
+    // @formatter:on
+    @Test
+    void test() throws Exception {
+        // given
+        Order order = new Order(OrderFixtureUtils.orderLineItemsWorthNDollars(100));
+        SpecialDiscountPolicy discountPolicy = new SpecialDiscountPolicy() {
+
+            @Override
+            public double discount(Order order) {
+                return 0.10;
+            }
+
+            @Override
+            public double discount(SpecialOrder order) {
+                return 0;
+            }
+        };
+
+        // when
+        Money totalCostAfterDiscount = order.totalCost(discountPolicy);
+
+        // then
+        assertThat(totalCostAfterDiscount).isEqualTo(Money.of(CurrencyUnit.USD, 90));
+    }
+
+    // @formatter:off
+    @DisplayName(
+        "given special order eligible for extra discount with items worth $100 total, " +
+        "when apply 20% discount policy for extra discount orders, " +
+        "then cost after discount is $80"
+        )
+    // @formatter:on
+    @Test
+    void test1() throws Exception {
+        // given
+        boolean eligibleForExtraDiscount = true;
+        Order order = new SpecialOrder(OrderFixtureUtils.orderLineItemsWorthNDollars(100), eligibleForExtraDiscount);
+        SpecialDiscountPolicy discountPolicy = new SpecialDiscountPolicy() {
+
+            @Override
+            public double discount(Order order) {
+                return 0;
+            }
+
+            @Override
+            public double discount(SpecialOrder order) {
+                if (order.isEligibleForExtraDiscount())
+                    return 0.20;
+                return 0.10;
+            }
+        };
+
+        // when
+        Money totalCostAfterDiscount = order.totalCost(discountPolicy);
+
+        // then
+        assertThat(totalCostAfterDiscount).isEqualTo(Money.of(CurrencyUnit.USD, 80.00));
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/doubledispatch/HtmlOrderViewCreatorUnitTest.java

@@ -0,0 +1,43 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.ddd.order.doubledispatch.Order;
+import com.baeldung.ddd.order.OrderFixtureUtils;
+import com.baeldung.ddd.order.OrderLine;
+import com.baeldung.ddd.order.doubledispatch.visitor.HtmlOrderViewCreator;
+
+public class HtmlOrderViewCreatorUnitTest {
+    // @formatter:off 
+    @DisplayName(
+            "given collection of regular and special orders, " +
+            "when create HTML view using visitor for each order, " +
+            "then the dedicated view is created for each order"   
+        )
+    // @formatter:on
+    @Test
+    void test() throws Exception {
+        // given
+        List<OrderLine> anyOrderLines = OrderFixtureUtils.anyOrderLines();
+        List<Order> orders = Arrays.asList(new Order(anyOrderLines), new SpecialOrder(anyOrderLines));
+        HtmlOrderViewCreator htmlOrderViewCreator = new HtmlOrderViewCreator();
+
+        // when
+        orders.get(0)
+            .accept(htmlOrderViewCreator);
+        String regularOrderHtml = htmlOrderViewCreator.getHtml();
+        orders.get(1)
+            .accept(htmlOrderViewCreator);
+        String specialOrderHtml = htmlOrderViewCreator.getHtml();
+
+        // then
+        assertThat(regularOrderHtml).containsPattern("<p>Regular order total cost: .*</p>");
+        assertThat(specialOrderHtml).containsPattern("<h1>Special Order</h1><p>total cost: .*</p>");
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/doubledispatch/MethodOverloadExampleUnitTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.List;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.ddd.order.doubledispatch.Order;
+import com.baeldung.ddd.order.OrderFixtureUtils;
+import com.baeldung.ddd.order.OrderLine;
+import com.baeldung.ddd.order.doubledispatch.SpecialDiscountPolicy;
+import com.baeldung.ddd.order.doubledispatch.SpecialOrder;
+
+public class MethodOverloadExampleUnitTest {
+// @formatter:off
+@DisplayName(
+    "given discount policy accepting special orders, " +
+    "when apply the policy on special order declared as regular order, " +
+    "then regular discount method is used"
+    )
+// @formatter:on    
+    @Test
+    void test() throws Exception {
+        // given
+        SpecialDiscountPolicy specialPolicy = new SpecialDiscountPolicy() {
+            @Override
+            public double discount(Order order) {
+                return 0.01;
+            }
+
+            @Override
+            public double discount(SpecialOrder order) {
+                return 0.10;
+            }
+        };
+        Order specialOrder = new SpecialOrder(anyOrderLines());
+
+        // when
+        double discount = specialPolicy.discount(specialOrder);
+
+        // then
+        assertThat(discount).isEqualTo(0.01);
+    }
+
+    private List<OrderLine> anyOrderLines() {
+        return OrderFixtureUtils.anyOrderLines();
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/doubledispatch/SingleDispatchDiscountPolicyUnitTest.java

@@ -0,0 +1,37 @@
+package com.baeldung.ddd.order.doubledispatch;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+import com.baeldung.ddd.order.OrderFixtureUtils;
+
+public class SingleDispatchDiscountPolicyUnitTest {
+    // @formatter:off
+    @DisplayName(
+        "given two discount policies, " +
+        "when use these policies, " +
+        "then single dispatch chooses the implementation based on runtime type"
+        )
+    // @formatter:on    
+    @Test
+    void test() throws Exception {
+        // given
+        DiscountPolicy flatPolicy = new FlatDiscountPolicy();
+        DiscountPolicy amountPolicy = new AmountBasedDiscountPolicy();
+        Order orderWorth501Dollars = orderWorthNDollars(501);
+
+        // when
+        double flatDiscount = flatPolicy.discount(orderWorth501Dollars);
+        double amountDiscount = amountPolicy.discount(orderWorth501Dollars);
+
+        // then
+        assertThat(flatDiscount).isEqualTo(0.01);
+        assertThat(amountDiscount).isEqualTo(0.1);
+    }
+
+    private Order orderWorthNDollars(int totalCost) {
+        return new Order(OrderFixtureUtils.orderLineItemsWorthNDollars(totalCost));
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/jpa/PersistOrderIntegrationTest.java

@@ -0,0 +1,40 @@
+package com.baeldung.ddd.order.jpa;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.math.BigDecimal;
+import java.util.Arrays;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+@SpringJUnitConfig
+@SpringBootTest
+public class PersistOrderIntegrationTest {
+    @Autowired
+    private JpaOrderRepository repository;
+
+    @DisplayName("given order with two line items, when persist, then order is saved")
+    @Test
+    public void test() throws Exception {
+        // given
+        JpaOrder order = prepareTestOrderWithTwoLineItems();
+
+        // when
+        JpaOrder savedOrder = repository.save(order);
+
+        // then
+        JpaOrder foundOrder = repository.findById(savedOrder.getId())
+            .get();
+        assertThat(foundOrder.getOrderLines()).hasSize(2);
+    }
+
+    private JpaOrder prepareTestOrderWithTwoLineItems() {
+        JpaOrderLine ol0 = new JpaOrderLine(new JpaProduct(BigDecimal.valueOf(10.00), "USD"), 2);
+        JpaOrderLine ol1 = new JpaOrderLine(new JpaProduct(BigDecimal.valueOf(5.00), "USD"), 10);
+        return new JpaOrder(Arrays.asList(ol0, ol1));
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/jpa/ViolateOrderBusinessRulesUnitTest.java

@@ -0,0 +1,35 @@
+package com.baeldung.ddd.order.jpa;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.math.BigDecimal;
+
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+
+public class ViolateOrderBusinessRulesUnitTest {
+    @DisplayName("given two non-zero order line items, when create an order with them, it's possible to set total cost to zero")
+    @Test
+    void test() throws Exception {
+        // given
+        // available products
+        JpaProduct lungChingTea = new JpaProduct(BigDecimal.valueOf(10.00), "USD");
+        JpaProduct gyokuroMiyazakiTea = new JpaProduct(BigDecimal.valueOf(20.00), "USD");
+        // Lung Ching tea order line
+        JpaOrderLine orderLine0 = new JpaOrderLine(lungChingTea, 2);
+        // Gyokuro Miyazaki tea order line
+        JpaOrderLine orderLine1 = new JpaOrderLine(gyokuroMiyazakiTea, 3);
+
+        // when
+        // create the order
+        JpaOrder order = new JpaOrder();
+        order.addLineItem(orderLine0);
+        order.addLineItem(orderLine1);
+        order.setTotalCost(BigDecimal.ZERO);
+        order.setCurrencyUnit("USD");
+
+        // then
+        // this doesn't look good...
+        assertThat(order.getTotalCost()).isEqualTo(BigDecimal.ZERO);
+    }
+}

ddd/src/test/java/com/baeldung/ddd/order/mongo/OrderMongoIntegrationTest.java

@@ -0,0 +1,50 @@
+package com.baeldung.ddd.order.mongo;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+import java.util.Arrays;
+import java.util.List;
+
+import org.joda.money.CurrencyUnit;
+import org.joda.money.Money;
+import org.junit.jupiter.api.DisplayName;
+import org.junit.jupiter.api.Test;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit.jupiter.SpringJUnitConfig;
+
+import com.baeldung.ddd.order.Order;
+import com.baeldung.ddd.order.OrderLine;
+import com.baeldung.ddd.order.Product;
+
+@SpringJUnitConfig
+@SpringBootTest
+public class OrderMongoIntegrationTest {
+    @Autowired
+    private OrderMongoRepository repo;
+
+    @DisplayName("given order with two line items, when persist using mongo repository, then order is saved")
+    @Test
+    void test() throws Exception {
+        // given
+        Order order = prepareTestOrderWithTwoLineItems();
+
+        // when
+        repo.save(order);
+
+        // then
+        List<Order> foundOrders = repo.findAll();
+        assertThat(foundOrders).hasSize(1);
+        List<OrderLine> foundOrderLines = foundOrders.iterator()
+            .next()
+            .getOrderLines();
+        assertThat(foundOrderLines).hasSize(2);
+        assertThat(foundOrderLines).containsOnlyElementsOf(order.getOrderLines());
+    }
+
+    private Order prepareTestOrderWithTwoLineItems() {
+        OrderLine ol0 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 10.00)), 2);
+        OrderLine ol1 = new OrderLine(new Product(Money.of(CurrencyUnit.USD, 5.00)), 10);
+        return new Order(Arrays.asList(ol0, ol1));
+    }
+}