functional bean registration test (#2503)

spring-5/src/main/java/com/baeldung/functional/MyService.java

@@ -0,0 +1,13 @@
+package com.baeldung.functional;
+
+import java.util.Random;
+
+import org.springframework.stereotype.Component;
+
+public class MyService {
+
+    public int getRandomNumber(){
+        return (new Random().nextInt(10));
+    }
+    
+}

spring-5/src/test/java/com/baeldung/functional/BeanRegistrationTest.java

@@ -0,0 +1,42 @@
+package com.baeldung.functional;
+
+import static org.junit.Assert.*;
+
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.springframework.beans.factory.annotation.Autowired;
+import org.springframework.boot.test.context.SpringBootTest;
+import org.springframework.test.context.junit4.SpringRunner;
+import org.springframework.web.context.support.GenericWebApplicationContext;
+
+import com.baeldung.Spring5Application;
+
+@RunWith(SpringRunner.class)
+@SpringBootTest(classes = Spring5Application.class)
+public class BeanRegistrationTest {
+
+    @Autowired
+    private GenericWebApplicationContext context;
+
+    @Test
+    public void whenRegisterBean_thenOk() {
+        context.registerBean(MyService.class, () -> new MyService());
+        MyService myService = (MyService) context.getBean("com.baeldung.functional.MyService");
+        assertTrue(myService.getRandomNumber() < 10);
+    }
+
+    @Test
+    public void whenRegisterBeanWithName_thenOk() {
+        context.registerBean("mySecondService", MyService.class, () -> new MyService());
+        MyService mySecondService = (MyService) context.getBean("mySecondService");
+        assertTrue(mySecondService.getRandomNumber() < 10);
+    }
+
+    @Test
+    public void whenRegisterBeanWithCallback_thenOk() {
+        context.registerBean("myCallbackService", MyService.class, () -> new MyService(), bd -> bd.setAutowireCandidate(false));
+        MyService myCallbackService = (MyService) context.getBean("myCallbackService");
+        assertTrue(myCallbackService.getRandomNumber() < 10);
+    }
+
+}