Add example of chain builders with tests

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/creational/builder/chain/inner/Task.java

@@ -0,0 +1,59 @@
+package pl.mperor.lab.java.design.pattern.creational.builder.chain.inner;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class Task {
+
+    private static final AtomicInteger ID_GENERATOR = new AtomicInteger(1);
+
+    private int id;
+    private String description;
+    private boolean done;
+
+    private Task() {
+    }
+
+    private Task(Task task) {
+        this.id = ID_GENERATOR.getAndIncrement();
+        // Deep copy is required here!
+        this.description = task.description;
+        this.done = task.done;
+    }
+
+    public int getId() {
+        return id;
+    }
+
+    public String getDescription() {
+        return description;
+    }
+
+    public boolean isDone() {
+        return done;
+    }
+
+    public static Builder builder() {
+        return new Task().new Builder();
+    }
+
+    public class Builder {
+
+        private Builder() {
+        }
+
+        public Builder description(String description) {
+            Task.this.description = description;
+            return this;
+        }
+
+        public Builder done(boolean done) {
+            Task.this.done = done;
+            return this;
+        }
+
+        public Task build() {
+            return new Task(Task.this);
+        }
+    }
+
+}

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/creational/builder/chain/nested/User.java

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+package pl.mperor.lab.java.design.pattern.creational.builder.chain.nested;
+
+import java.util.concurrent.atomic.AtomicInteger;
+
+public class User {
+
+    private static final AtomicInteger ID_GENERATOR = new AtomicInteger(1);
+
+    private int id;
+    private String name;
+    private String password;
+    private String email;
+
+    private User() {
+    }
+
+    private User(User user) {
+        this.id = ID_GENERATOR.getAndIncrement();
+        // Deep copy is required here!
+        this.name = user.name;
+        this.password = user.password;
+        this.email = user.email;
+    }
+
+    int getId() {
+        return id;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public String getPassword() {
+        return password;
+    }
+
+    public String getEmail() {
+        return email;
+    }
+
+    public static Builder builder() {
+        return new Builder();
+    }
+
+    public static class Builder {
+
+        private final User user;
+
+        private Builder() {
+            this.user = new User();
+        }
+
+        public Builder name(String name) {
+            this.user.name = name;
+            return this;
+        }
+
+        public Builder password(String password) {
+            user.password = password;
+            return this;
+        }
+
+        public Builder email(String email) {
+            user.email = email;
+            return this;
+        }
+
+        public User build() {
+            return new User(user);
+        }
+    }
+}

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/creational/builder/chain/outer/Person.java

@@ -0,0 +1,39 @@
+package pl.mperor.lab.java.design.pattern.creational.builder.chain.outer;
+
+import java.time.LocalDate;
+
+public class Person {
+
+    private final String firstName;
+    private final String lastName;
+    private final LocalDate dateOfBirth;
+    private final String address;
+
+    private Person(PersonBuilder builder) {
+        this.firstName = builder.getFirstName();
+        this.lastName = builder.getLastName();
+        this.dateOfBirth = builder.getDateOfBirth();
+        this.address = builder.getAddress();
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public LocalDate getDateOfBirth() {
+        return dateOfBirth;
+    }
+
+    public String getAddress() {
+        return address;
+    }
+
+    public static Person build(PersonBuilder builder) {
+        return new Person(builder);
+    }
+
+}

DesignPatterns/src/main/java/pl/mperor/lab/java/design/pattern/creational/builder/chain/outer/PersonBuilder.java

@@ -0,0 +1,48 @@
+package pl.mperor.lab.java.design.pattern.creational.builder.chain.outer;
+
+import java.time.LocalDate;
+
+public class PersonBuilder {
+
+    private String firstName;
+    private String lastName;
+    private LocalDate dateOfBirth;
+    private String address;
+
+    public PersonBuilder firstName(String name) {
+        this.firstName = name;
+        return this;
+    }
+
+    public PersonBuilder lastName(String name) {
+        this.lastName = name;
+        return this;
+    }
+
+    public PersonBuilder dateOfBirth(LocalDate date) {
+        this.dateOfBirth = date;
+        return this;
+    }
+
+    public PersonBuilder address(String address) {
+        this.address = address;
+        return this;
+    }
+
+    public String getFirstName() {
+        return firstName;
+    }
+
+    public String getLastName() {
+        return lastName;
+    }
+
+    public LocalDate getDateOfBirth() {
+        return dateOfBirth;
+    }
+
+    public String getAddress() {
+        return address;
+    }
+
+}

DesignPatterns/src/test/java/pl/mperor/lab/java/design/pattern/creational/builder/chain/inner/TaskInnerBuilderTest.java

@@ -0,0 +1,38 @@
+package pl.mperor.lab.java.design.pattern.creational.builder.chain.inner;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class TaskInnerBuilderTest {
+
+    @Test
+    public void builderShouldAllowToBuildTask() {
+        Task task = Task.builder()
+                .build();
+
+        Assertions.assertNotNull(task);
+        Assertions.assertTrue(task.getId() >= 1);
+        Assertions.assertNull(task.getDescription());
+        Assertions.assertFalse(task.isDone());
+    }
+
+    @Test
+    public void builderShouldAllowToBuildDoneTasks() {
+        var builder = Task.builder()
+                .done(true);
+
+        Task t1 = builder
+                .description("First task")
+                .build();
+
+        Task t2 = builder
+                .description("Second task")
+                .build();
+
+        Assertions.assertEquals("First task", t1.getDescription());
+        Assertions.assertEquals("Second task", t2.getDescription());
+        Assertions.assertTrue(t1.isDone() && t2.isDone());
+        Assertions.assertNotEquals(t1.getId(), t2.getId());
+    }
+
+}

DesignPatterns/src/test/java/pl/mperor/lab/java/design/pattern/creational/builder/chain/nested/UserNestedStaticBuilderTest.java

@@ -0,0 +1,56 @@
+package pl.mperor.lab.java.design.pattern.creational.builder.chain.nested;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+public class UserNestedStaticBuilderTest {
+
+    @Test
+    public void userBuilderShouldAllowToBuildUser() {
+        User user = User.builder().build();
+        Assertions.assertNotNull(user);
+        Assertions.assertTrue(user.getId() >= 1);
+        Assertions.assertNull(user.getName());
+        Assertions.assertNull(user.getPassword());
+    }
+
+    @Test
+    public void userBuilderShouldAllowToBuildCustomUser() {
+        User custom = User.builder()
+                .name("user")
+                .password("{noop}password")
+                .email("user@example.com")
+                .build();
+
+        Assertions.assertTrue(custom.getId() >= 1);
+        Assertions.assertEquals("user", custom.getName());
+        Assertions.assertNotNull(custom.getPassword());
+        Assertions.assertEquals("user@example.com", custom.getEmail());
+    }
+
+    @Test
+    public void userBuilderShouldAllowToBuildGroupOfUsers() {
+        var builder = User.builder();
+        User u1 = builder
+                .name("Anonymous")
+                .email("anonymous@example.com")
+                .build();
+        Assertions.assertEquals("Anonymous", u1.getName());
+        Assertions.assertEquals("anonymous@example.com", u1.getEmail());
+
+        User u2 = builder
+                .email("admin@example.com")
+                .build();
+        Assertions.assertEquals("Anonymous", u2.getName());
+        Assertions.assertEquals("admin@example.com", u2.getEmail());
+
+        User u3 = User.builder()
+                .email("noname@example.com")
+                .build();
+        Assertions.assertNull(u3.getName());
+        Assertions.assertEquals("noname@example.com", u3.getEmail());
+
+        Assertions.assertTrue(u1.getId() < u2.getId() && u2.getId() < u3.getId());
+    }
+
+}

DesignPatterns/src/test/java/pl/mperor/lab/java/design/pattern/creational/builder/chain/outer/PersonOuterBuilderTest.java

@@ -0,0 +1,27 @@
+package pl.mperor.lab.java.design.pattern.creational.builder.chain.outer;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+
+import java.time.LocalDate;
+import java.time.Month;
+
+public class PersonOuterBuilderTest {
+
+    @Test
+    public void personShouldBeCreatedByPersonBuilder() {
+        Person person = Person.build(new PersonBuilder()
+                .firstName("Jack")
+                .lastName("Bell")
+                .address("New York")
+                .dateOfBirth(LocalDate.of(1990, Month.JANUARY, 1)));
+
+        Assertions.assertNotNull(person);
+        Assertions.assertEquals("Jack", person.getFirstName());
+        Assertions.assertEquals("Bell", person.getLastName());
+        Assertions.assertEquals("New York", person.getAddress());
+        Assertions.assertEquals("1990-01-01", person.getDateOfBirth().toString());
+    }
+
+
+}