From fbb30b15b9f1fed41401bf93030cfaece9c7f9cd Mon Sep 17 00:00:00 2001
From: Brent Roose <brent@spatie.be>
Date: Tue, 8 Jan 2019 13:55:43 +0100
Subject: [PATCH] No overlap returns empty collection

---
 CHANGELOG.md         | 4 ++++
 src/Period.php       | 8 +++++++-
 tests/PeriodTest.php | 9 +++++++++
 3 files changed, 20 insertions(+), 1 deletion(-)

diff --git a/CHANGELOG.md b/CHANGELOG.md
index ebbc4aa..d072153 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -6,6 +6,10 @@ All notable changes to `period` will be documented in this file
 
 - initial release
 
+## 0.4.1 - 2019-01-08
+
+- No overlap returns empty collection
+
 ## 0.4.0 - 2018-12-19
 
 - Add visualizer
diff --git a/src/Period.php b/src/Period.php
index 3d577cd..a1a980a 100644
--- a/src/Period.php
+++ b/src/Period.php
@@ -263,7 +263,13 @@ public function overlap(Period ...$periods): PeriodCollection
         $overlapCollection = new PeriodCollection();
 
         foreach ($periods as $period) {
-            $overlapCollection[] = $this->overlapSingle($period);
+            $overlap = $this->overlapSingle($period);
+
+            if ($overlap === null) {
+                continue;
+            }
+
+            $overlapCollection[] = $overlap;
         }
 
         return $overlapCollection;
diff --git a/tests/PeriodTest.php b/tests/PeriodTest.php
index a04df74..f364d8e 100644
--- a/tests/PeriodTest.php
+++ b/tests/PeriodTest.php
@@ -176,6 +176,15 @@ public function it_can_determine_the_overlap_between_multiple_periods()
         $this->assertTrue($overlap->equals(Period::make('2018-01-10', '2018-01-15')));
     }
 
+    /** @test */
+    public function non_overlapping_dates_return_an_empty_collection()
+    {
+        $a = Period::make('2019-01-01', '2019-01-31');
+        $b = Period::make('2019-02-01', '2019-02-28');
+
+        $this->assertTrue($a->overlap($b)->isEmpty());
+    }
+
     /** @test */
     public function it_can_determine_that_two_periods_do_not_overlap()
     {