init commit - a guide to java initialization classes and resources

core-java/src/test/java/com/baeldung/initializationguide/UserTest.java

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+package com.baeldung.initializationguide;
+import org.junit.Before;
+import org.junit.Test;
+
+import static org.assertj.core.api.Assertions.*;
+
+import java.io.BufferedInputStream;
+import java.io.BufferedOutputStream;
+import java.io.FileInputStream;
+import java.io.FileNotFoundException;
+import java.io.FileOutputStream;
+import java.io.IOException;
+import java.io.ObjectInputStream;
+import java.io.ObjectOutputStream;
+import java.lang.reflect.InvocationTargetException;
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.nio.file.Paths;
+
+public class UserTest {
+
+
+    Path userData;
+
+    @Before
+    public void init() throws IOException {
+        userData = Paths.get("src/test/resources/user.data");
+        if (!Files.exists(userData))
+            Files.createFile(userData);
+    }
+
+    @Test
+    public void givenUserInstance_whenIntializedWithNew_thenInstanceIsNotNull() {
+        User user = new User("Alice", 1);
+        assertThat(user).isNotNull();
+    }
+
+    @Test
+    public void givenUserInstance_whenInitializedWithReflection_thenInstanceIsNotNull() throws InstantiationException, IllegalAccessException, IllegalArgumentException, InvocationTargetException, NoSuchMethodException, SecurityException {
+        User user = User.class.getConstructor(String.class, int.class)
+            .newInstance("Alice", 2);
+        assertThat(user).isNotNull();
+    }
+
+    @Test
+    public void givenUserInstance_whenCopiedWithClone_thenExactMatchIsCreated() throws CloneNotSupportedException {
+        User user = new User("Alice", 3);
+        User clonedUser = (User) user.clone();
+        assertThat(clonedUser).isEqualTo(user);
+    }
+
+    @Test
+    public void givenFileWithBitsRepresentingUser_whenDeserialized_thenUserIsCreated() throws FileNotFoundException, IOException, ClassNotFoundException {
+        try (ObjectOutputStream out = new ObjectOutputStream(new BufferedOutputStream(new FileOutputStream(userData.toFile())))) {
+            User user = new User("Tom", 0);
+            out.writeObject(user);
+        }
+        try (ObjectInputStream in = new ObjectInputStream(new BufferedInputStream(new FileInputStream(userData.toFile())))) {
+            User deserializedUser = (User) in.readObject();
+            assertThat(deserializedUser).isNotNull();
+        }
+    }
+
+    @Test
+    public void givenUserInstance_whenValuesAreNotInitialized_thenUserNameAndIdReturnDefault() {
+        User user = new User();
+        assertThat(user.getName()).isNull();
+        assertThat(user.getId() == 0);
+    }
+}