BAEL-4404 | Added test class to verify the beahvior

spring-boot-modules/spring-boot-mvc-3/src/test/java/com/baeldung/charencoding/controller/CharEncodingCheckControllerTest.java

@@ -0,0 +1,34 @@
+package com.baeldung.charencoding.controller;
+
+import static org.mockito.Mockito.mock;
+import static org.mockito.Mockito.verify;
+
+import java.io.IOException;
+
+import javax.servlet.FilterChain;
+import javax.servlet.ServletException;
+import javax.servlet.http.HttpServletRequest;
+import javax.servlet.http.HttpServletResponse;
+
+import org.junit.jupiter.api.Test;
+import org.springframework.web.filter.CharacterEncodingFilter;
+
+class CharEncodingCheckControllerTest {
+
+    @Test
+    void whenCharEncodingFilter_thenVerifyEncoding() throws ServletException, IOException {
+        HttpServletRequest request = mock(HttpServletRequest.class);
+        HttpServletResponse response = mock(HttpServletResponse.class);
+        FilterChain chain = mock(FilterChain.class);
+        
+        CharacterEncodingFilter filter = new CharacterEncodingFilter();
+        filter.setEncoding("UTF-8");
+        filter.setForceEncoding(true);
+        
+        filter.doFilter(request, response, chain);
+        
+        verify(request).setCharacterEncoding("UTF-8");
+        verify(response).setCharacterEncoding("UTF-8");
+    }
+
+}