Add 3 Junit tests

src/main/java/van/AddCommand.java

@@ -12,4 +12,9 @@ public boolean executeCommand(Ui ui, TaskList taskList, Storage storage) {
     ui.taskMessage(newTask, taskList.getTaskCount());
     return false;
   }
+
+  @Override
+  public String toString() {
+    return newTask.getStatus();
+  }
 }

src/main/java/van/Parser.java

@@ -39,7 +39,7 @@ public static Command parseCommand(String parameter) {
           if (parameters.length != 2) {
             throw new VanException("Invalid format. Please use: event <task> /at <date>");
           }
-          taskArguments = parameters[1].split(" /by ");
+          taskArguments = parameters[1].split(" /at ");
           if (taskArguments.length != 2) {
             throw new VanException("Invalid format. Please use: event <task> /at <date>");
           }

src/test/java/van/ParserTest.java

@@ -0,0 +1,29 @@
+package van;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class ParserTest {
+  @Test
+  public void deadLineTester() {
+    Command deadLine = Parser.parseCommand("deadline eat /by 22-10-2022 18:00");
+
+    assertEquals("[D][ ] eat (by:Oct 22 2022 1800)"
+      , deadLine.toString());
+  }
+
+  @Test
+  public void eventTester() {
+    Command eventTest = Parser.parseCommand("event sleep /at 12-01-2022 06:00");
+    assertEquals("[E][ ] sleep (at:Jan 12 2022 0600)",
+      eventTest.toString());
+  }
+
+  @Test
+  public void toDoTester() {
+    Command toDoTest = Parser.parseCommand("todo study");
+    assertEquals("[T][ ] study", toDoTest.toString());
+  }
+
+}