add unit test of TodoItem

app/src/test/java/org/cutem/cutecalendar/model/TodoItemTest.java

@@ -0,0 +1,62 @@
+package org.cutem.cutecalendar.model;
+
+import org.cutem.cutecalendar.util.CalendarUtil;
+import org.junit.Test;
+
+import java.util.Calendar;
+
+import static org.junit.Assert.*;
+
+public class TodoItemTest {
+
+    @Test
+    public void testConstruction() {
+        Calendar cal = CalendarUtil.roundToMinute(Calendar.getInstance());
+
+        long id = 1;
+        String title = "hello";
+        Calendar[] whole = CalendarUtil.getWholeDayPeriod(cal);
+        int type = TodoItem.OTHERS;
+
+        new TodoItem(id, title, whole[0], whole[1], type);
+
+        boolean ok = false;
+        cal = whole[0];
+        whole[0] = whole[1];
+        whole[1] = cal;
+        try {
+            new TodoItem(id, title, whole[0], whole[1], type);
+        } catch (IllegalArgumentException e) {
+            ok = true;
+        }
+
+        assertTrue(ok);
+    }
+
+    @Test
+    public void equalsAndHashCode() {
+        Calendar cal = CalendarUtil.roundToMinute(Calendar.getInstance());
+
+        String title = "hello";
+        Calendar[] whole = CalendarUtil.getWholeDayPeriod(cal);
+        int type = TodoItem.OTHERS;
+
+        TodoItem item1 = new TodoItem(1L, title, whole[0], whole[1], type);
+        TodoItem item2 = new TodoItem(2L, title, whole[0], whole[1], type);
+        TodoItem item3 = new TodoItem(1L, title, whole[0], whole[1], type);
+        Object item4 = new Object();
+
+        assertNotEquals(item1, item2);
+        assertEquals(item1, item3);
+        assertNotEquals(item1, item4);
+
+        System.out.println(item1.hashCode());
+        System.out.println(item2.hashCode());
+        System.out.println(item3.hashCode());
+        System.out.println(item4.hashCode());
+        assertNotEquals(item1.hashCode(), item2.hashCode());
+        assertEquals(item1.hashCode(), item3.hashCode());
+        assertNotEquals(item1.hashCode(), item4.hashCode());
+    }
+
+}