Adds tests for ClientHandler

pom.xml

@@ -40,6 +40,12 @@
             <artifactId>log4j-core</artifactId>
             <version>2.17.1</version>
         </dependency>
+        <dependency>
+            <groupId>io.github.hakky54</groupId>
+            <artifactId>logcaptor</artifactId>
+            <version>2.7.8</version>
+            <scope>test</scope>
+        </dependency>
     </dependencies>
     <build>
         <plugins>

src/test/java/org/fungover/storm/client/ClientHandlerTest.java

@@ -0,0 +1,41 @@
+package org.fungover.storm.client;
+
+import nl.altindag.log.LogCaptor;
+import org.junit.jupiter.api.Test;
+import org.mockito.Mockito;
+
+import java.io.*;
+import java.net.Socket;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.mock;
+
+
+class ClientHandlerTest {
+
+    @Test
+    void shouldNotLogAnErrorWhenThereIsASuccessfulConnection() throws IOException {
+        LogCaptor logCaptor = LogCaptor.forName("SERVER");
+        Socket socket = mock(Socket.class);
+        Mockito.when(socket.getOutputStream()).thenReturn(new ByteArrayOutputStream());
+        Mockito.when(socket.getInputStream()).thenReturn(new ByteArrayInputStream("Hello Storm!".getBytes()));
+        ClientHandler clientHandler = new ClientHandler(socket);
+
+        clientHandler.run();
+
+        assertThat(logCaptor.getErrorLogs()).isEmpty();
+    }
+
+    @Test
+    void shouldLogAnErrorWhenThereIsAConnectionError() throws IOException {
+        LogCaptor logCaptor = LogCaptor.forName("SERVER");
+        Socket socket = new Socket();
+        ClientHandler clientHandler = new ClientHandler(socket);
+
+        socket.close();
+        clientHandler.run();
+
+        assertThat(logCaptor.getErrorLogs()).hasSize(1);
+    }
+
+}