BAEL-1527 (#4324)

* commit first as binodpanta

* revert test change

* A short example of real-time event streaming using Spring WebFlux

* Code for http://jira.baeldung.com/browse/BAEL-1527

* remove unrelated files

* Apply feedback changes to rename test and remove link from readme file, ongoing work

* Update formatting fixes to code and add pom changes, that partially fix test runnning issues in IDE but not in cmdline

* Apply Eclipse formatter to test code and apply suggested pom fixes

* BAEL-1527 Formatting fix in pom.xml

testing-modules/junit-5/src/test/java/com/baeldung/RegisterExtensionUnitTest.java

@@ -0,0 +1,27 @@
+package com.baeldung;
+
+import com.baeldung.extensions.RegisterExtensionSampleExtension;
+
+import org.junit.jupiter.api.Assertions;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.RegisterExtension;
+
+/**
+ * This test demonstrates the use of the same extension in two ways.
+ * 1. Once as instance level field: Only method level callbacks are called.
+ * 2. Once as class level static field: All methods are called.
+ */
+public class RegisterExtensionUnitTest {
+
+    @RegisterExtension
+    static RegisterExtensionSampleExtension staticExtension = new RegisterExtensionSampleExtension("static version");
+
+    @RegisterExtension
+    RegisterExtensionSampleExtension instanceLevelExtension = new RegisterExtensionSampleExtension("instance version");
+
+    @Test
+    public void demoTest() {
+        Assertions.assertEquals("instance version", instanceLevelExtension.getType());
+    }
+
+}

testing-modules/junit-5/src/test/java/com/baeldung/extensions/RegisterExtensionSampleExtension.java

@@ -0,0 +1,34 @@
+package com.baeldung.extensions;
+
+import org.junit.jupiter.api.extension.BeforeAllCallback;
+import org.junit.jupiter.api.extension.BeforeEachCallback;
+import org.junit.jupiter.api.extension.ExtensionContext;
+import org.slf4j.Logger;
+import org.slf4j.LoggerFactory;
+
+/**
+ * This extension is meant to demonstrate the use of RegisterExtension.
+ */
+public class RegisterExtensionSampleExtension implements BeforeAllCallback, BeforeEachCallback {
+
+    private final String type;
+    Logger logger = LoggerFactory.getLogger(RegisterExtensionSampleExtension.class);
+
+    public RegisterExtensionSampleExtension(String type) {
+        this.type = type;
+    }
+
+    @Override
+    public void beforeAll(ExtensionContext extensionContext) throws Exception {
+        logger.info("Type " + type + " In beforeAll : " + extensionContext.getDisplayName());
+    }
+
+    @Override
+    public void beforeEach(ExtensionContext extensionContext) throws Exception {
+        logger.info("Type " + type + " In beforeEach : " + extensionContext.getDisplayName());
+    }
+
+    public String getType() {
+        return type;
+    }
+}