diff --git a/src/Period/Day.php b/src/Period/Day.php
index b99e920..e29fa2d 100644
--- a/src/Period/Day.php
+++ b/src/Period/Day.php
@@ -64,14 +64,4 @@ public function isHoliday()
 
         return false;
     }
-
-    /**
-     * It's unnecessary defining this method. It's here only to allow IDE type hinting.
-     *
-     * @return Day
-     */
-    public function current()
-    {
-        return current($this->dates);
-    }
 }
diff --git a/src/Period/Month.php b/src/Period/Month.php
index 7b26efc..aa6e740 100644
--- a/src/Period/Month.php
+++ b/src/Period/Month.php
@@ -37,7 +37,7 @@ public function isOutOfMonth($period)
     {
         if ($period instanceof \DateTime)
         {
-            return !$this->overlaps(new Day($period));
+            return !$this->overlaps(new Day($period->format('Y-m-d')));
         }
 
         return !$this->overlaps($period);
@@ -50,6 +50,6 @@ public function isOutOfMonth($period)
      */
     public function current()
     {
-        return current($this->dates);
+        return parent::current();
     }
 }
diff --git a/src/Period/Week.php b/src/Period/Week.php
index e682e38..547b7bd 100644
--- a/src/Period/Week.php
+++ b/src/Period/Week.php
@@ -57,6 +57,6 @@ public static function getFirstDayOfWeek(\DateTime $a_day)
      */
     public function current()
     {
-        return current($this->dates);
+        return parent::current();
     }
 }
diff --git a/src/Period/Year.php b/src/Period/Year.php
index ef528be..871d95c 100644
--- a/src/Period/Year.php
+++ b/src/Period/Year.php
@@ -35,6 +35,6 @@ public static function fromYear($year)
      */
     public function current()
     {
-        return current($this->dates);
+        return parent::current();
     }
 }
diff --git a/tests/Period/DayTest.php b/tests/Period/DayTest.php
index aa813b2..39581c0 100644
--- a/tests/Period/DayTest.php
+++ b/tests/Period/DayTest.php
@@ -16,8 +16,15 @@ public function validDay()
     /** @test */
     public function detectHoliday()
     {
-        $day = new Day('2015-01-01');
-        $this->assertTrue($day->isHoliday());
+        $day1 = new Day('2015-01-01');
+        $day2 = new Day('2015-04-06');
+        $day3 = new Day('2015-04-11');
+        $day4 = new Day('2015-04-15');
+
+        $this->assertTrue($day1->isHoliday());
+        $this->assertTrue($day2->isHoliday());
+        $this->assertTrue($day3->isHoliday());
+        $this->assertFalse($day4->isHoliday());
     }
 
     /** @test */
@@ -26,4 +33,21 @@ public function detectWeekend()
         $day = new Day('2015-09-27');
         $this->assertTrue($day->isWeekend());
     }
+
+    /** @test */
+    public function shouldDetectDifferentDays()
+    {
+        $day1 = new Day('2015-09-27');
+        $day2 = new Day('2015-09-26');
+
+        $this->assertFalse($day1->equals($day2));
+    }
+
+    /** @test */
+    public function shouldDetectCurrentDay()
+    {
+        $day = new Day('now');
+
+        $this->assertTrue($day->isCurrent());
+    }
 }
diff --git a/tests/Period/MonthTest.php b/tests/Period/MonthTest.php
index 5a2aedb..676708f 100644
--- a/tests/Period/MonthTest.php
+++ b/tests/Period/MonthTest.php
@@ -4,22 +4,43 @@
 
 use DateRanger\Period\Day;
 use DateRanger\Period\Month;
+use DateRanger\Period\Week;
 
 final class MonthTest extends \PHPUnit_Framework_TestCase
 {
     /** @test */
     public function validMonth()
     {
-        $month = new Month();
-        $this->assertEquals(date('Y-m'), $month->start()->format('Y-m'));
+        $month1 = new Month();
+        $this->assertEquals(date('Y-m'), $month1->start()->format('Y-m'));
+
+        $month2 = Month::fromMonth(date('Y'), date('m'));
+        $this->assertEquals(date('Y-m'), $month2->start()->format('Y-m'));
     }
 
     /** @test */
     public function outsiderDays()
     {
         $month = new Month('2015-09-01');
-        $day = new Day('2015-08-20');
 
-        $this->assertTrue($month->isOutOfMonth($day));
+        $day_inside         = new Day('2015-08-20');
+        $day_outside        = new Day('2015-09-20');
+        $day_outside_string = new \DateTime('2015-09-20');
+
+        $this->assertTrue($month->isOutOfMonth($day_inside));
+        $this->assertFalse($month->isOutOfMonth($day_outside));
+        $this->assertFalse($month->isOutOfMonth($day_outside_string));
+    }
+
+
+    /** @test */
+    public function shouldContainWeeks()
+    {
+        $week = new Month();
+        foreach ($week as $position => $day)
+        {
+            $this->assertInstanceOf(Week::class, $day);
+        }
     }
+
 }
diff --git a/tests/Period/WeekTest.php b/tests/Period/WeekTest.php
index f176d10..9c07bf3 100644
--- a/tests/Period/WeekTest.php
+++ b/tests/Period/WeekTest.php
@@ -2,6 +2,7 @@
 
 namespace DateRangerTest\Period;
 
+use DateRanger\Period\Day;
 use DateRanger\Period\Week;
 
 final class WeekTest extends \PHPUnit_Framework_TestCase
@@ -20,4 +21,14 @@ public function createFromWeekNumber()
         $week2 = Week::fromWeekNumber(2015, 7);
         $this->assertEquals($week1, $week2);
     }
+
+    /** @test */
+    public function shouldContainDays()
+    {
+        $week = new Week();
+        foreach ($week as $position => $day)
+        {
+            $this->assertInstanceOf(Day::class, $day);
+        }
+    }
 }
diff --git a/tests/Period/YearTest.php b/tests/Period/YearTest.php
index 97b45f1..84f37c9 100644
--- a/tests/Period/YearTest.php
+++ b/tests/Period/YearTest.php
@@ -2,6 +2,7 @@
 
 namespace DateRangerTest\Period;
 
+use DateRanger\Period\Month;
 use DateRanger\Period\Year;
 
 final class YearTest extends \PHPUnit_Framework_TestCase
@@ -11,8 +12,11 @@ final class YearTest extends \PHPUnit_Framework_TestCase
      */
     public function validYear()
     {
-        $year = new Year();
-        $this->assertEquals(date('Y'), $year->start()->format('Y'));
+        $year1 = new Year();
+        $this->assertEquals(date('Y'), $year1->start()->format('Y'));
+
+        $year2 = Year::fromYear(date('Y'));
+        $this->assertEquals(date('Y'), $year2->start()->format('Y'));
     }
 
     /**
@@ -23,4 +27,14 @@ public function validContents()
         $year = new Year();
         $this->assertEquals(12, count($year));
     }
+
+    /** @test */
+    public function shouldContainMonths()
+    {
+        $week = new Year();
+        foreach ($week as $position => $day)
+        {
+            $this->assertInstanceOf(Month::class, $day);
+        }
+    }
 }