BAEL-2066 - Java Constructors vs Static Factory Methods (#4934)

* Initial Commit

* Update User.java

* Update UserUnitTest.java

* Update User.java - UserUnitTest.java

core-java/src/test/java/com/baeldung/constructorsstaticfactorymethods/UserUnitTest.java

@@ -0,0 +1,43 @@
+package com.baeldung.constructorsstaticfactorymethods;
+
+import com.baeldung.constructorsstaticfactorymethods.entities.User;
+import static org.assertj.core.api.Assertions.assertThat;
+import org.junit.Test;
+
+public class UserUnitTest {
+    
+    @Test
+    public void givenUserClass_whenCalledcreateWithDefaultCountry_thenCorrect() {
+        assertThat(User.createWithDefaultCountry("John", "john@domain.com")).isInstanceOf(User.class);
+    }
+    
+    @Test
+    public void givenUserIntanceCreatedWithcreateWithDefaultCountry_whenCalledgetName_thenCorrect() {
+        User user = User.createWithDefaultCountry("John", "john@domain.com");
+        assertThat(user.getName()).isEqualTo("John");
+    }
+    
+    @Test
+    public void givenUserIntanceCreatedWithcreateWithDefaultCountry_whenCalledgetEmail_thenCorrect() {
+        User user = User.createWithDefaultCountry("John", "john@domain.com");
+        assertThat(user.getEmail()).isEqualTo("john@domain.com");
+    }
+    
+    @Test
+    public void givenUserIntanceCreatedWithcreateWithDefaultCountry_whenCalledgetCountry_thenCorrect() {
+        User user = User.createWithDefaultCountry("John", "john@domain.com");
+        assertThat(user.getCountry()).isEqualTo("Argentina");
+    }
+    
+    @Test
+    public void givenUserInstanceCreatedWithcreateWithInstantiationTime_whenCalledcreateWithInstantiationTime_thenCorrect() {
+        assertThat(User.createWithLoggedInstantiationTime("John", "john@domain.com", "Argentina")).isInstanceOf(User.class);
+    }
+    
+    @Test
+    public void givenUserInstanceCreatedWithgetSingletonIntance_whenCalledgetSingletonInstance_thenCorrect() {
+        User user1 = User.getSingletonInstance("John", "john@domain.com", "Argentina");
+        User user2 = User.getSingletonInstance("John", "john@domain.com", "Argentina");
+        assertThat(user1).isEqualTo(user2);
+    }
+}