add JUnit Tests

src/test/java/duke/EventTest.java

@@ -0,0 +1,15 @@
+package duke;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class EventTest {
+
+    Task task = new Event("read book", "31 Dec 2020");
+
+    @Test
+    public void testToString() {
+        assertEquals("[E][✘] read book (at: 31 Dec 2020)", task.toString());
+    }
+}

src/test/java/duke/StorageTest.java

@@ -0,0 +1,15 @@
+package duke;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class StorageTest {
+
+    Storage storage = new Storage("src/main/java/data/duke.txt");
+
+    @Test
+    public void testGetFilePath() {
+        assertEquals("src/main/java/data/duke.txt", storage.getFilePath());
+    }
+}

src/test/java/duke/TodoTest.java

@@ -0,0 +1,15 @@
+package duke;
+
+import org.junit.jupiter.api.Test;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class TodoTest {
+
+    Task task = new Todo("read book");
+
+    @Test
+    public void testToString() {
+        assertEquals("[T][✘] read book", task.toString());
+    }
+}