Feat: User

specification-pattern/src/main/java/com/currenjin/users/User.java

@@ -0,0 +1,27 @@
+package com.currenjin.users;
+
+public class User {
+    private final String name;
+    private final int age;
+
+    public User(String name, int age) {
+        if (age < 0) {
+            throw new IllegalArgumentException("Age must be a positive integer");
+        }
+
+        if (name == null || name.isBlank()) {
+            throw new IllegalArgumentException("Username cannot be null or empty");
+        }
+
+        this.name = name;
+        this.age = age;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+}

specification-pattern/src/test/java/com/currenjin/users/UserTest.java

@@ -0,0 +1,31 @@
+package com.currenjin.users;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.*;
+
+class UserTest {
+
+    public static final String NAME = "currenjin";
+    public static final int AGE = 24;
+
+    @Test
+    void field_test() {
+        User user = new User(NAME, AGE);
+
+        assertEquals(NAME, user.getName());
+        assertEquals(AGE, user.getAge());
+    }
+
+    @Test
+    void age_cannot_be_less_than_zero() {
+        assertThrows(IllegalArgumentException.class, () -> new User(NAME, -1));
+    }
+
+    @Test
+    void name_cannot_be_null_or_blank() {
+        assertThrows(IllegalArgumentException.class, () -> new User("", AGE));
+        assertThrows(IllegalArgumentException.class, () -> new User(" ", AGE));
+        assertThrows(IllegalArgumentException.class, () -> new User(null, AGE));
+    }
+}