Commit f434c97

@@ -34,7 +34,7 @@ public class WeekDay {
   }
 
   private void ensureValidDate(int year, int month, int day) {
-    if (day > MONTHS[month - 1]) throw new IllegalArgumentException();
+    if (day < 1 || day > MONTHS[month - 1]) throw new IllegalArgumentException();
   }
 
   public static void main(String[] args) {

@@ -64,7 +64,7 @@ public class WeekDayTest extends TestCase {
     assertEquals("Sunday", subject.getWeekDay(31, 1, 2100));
   }
 
-  public void test_getWeekDay_invalid_day() {
+  public void test_getWeekDay_day_too_large() {
     boolean raised = false;
     try {
       subject.getWeekDay(32, 1, 2100);
@@ -73,4 +73,14 @@ public class WeekDayTest extends TestCase {
     }
     assertTrue(raised);
   }
+
+  public void test_getWeekDay_day_too_small() {
+    boolean raised = false;
+    try {
+      subject.getWeekDay(0, 1, 2100);
+    } catch (IllegalArgumentException error) {
+      raised = true;
+    }
+    assertTrue(raised);
+  }
 }