Add Collection@isSingle method

src/Illuminate/Collections/Collection.php

@@ -553,6 +553,16 @@ public function isEmpty()
         return empty($this->items);
     }
 
+    /**
+     * Determine if the collection contains a single element.
+     *
+     * @return bool
+     */
+    public function isSingle()
+    {
+        return $this->count() === 1;
+    }
+
     /**
      * Join all items from the collection using a string. The final items can use a separate glue string.
      *

src/Illuminate/Collections/LazyCollection.php

@@ -556,6 +556,16 @@ public function isEmpty()
         return ! $this->getIterator()->valid();
     }
 
+    /**
+     * Determine if the collection contains a single element.
+     *
+     * @return bool
+     */
+    public function isSingle()
+    {
+        return $this->take(2)->count() === 1;
+    }
+
     /**
      * Join all items from the collection using a string. The final items can use a separate glue string.
      *

tests/Support/SupportCollectionTest.php

@@ -541,6 +541,16 @@ public function testCountableByWithCallback($collection)
         })->all());
     }
 
+    /**
+     * @dataProvider collectionClassProvider
+     */
+    public function testIsSingle($collection)
+    {
+        $this->assertFalse((new $collection([]))->isSingle());
+        $this->assertTrue((new $collection([1]))->isSingle());
+        $this->assertFalse((new $collection([1, 2]))->isSingle());
+    }
+
     public function testIterable()
     {
         $c = new Collection(['foo']);

tests/Support/SupportLazyCollectionIsLazyTest.php

@@ -484,6 +484,13 @@ public function testIsNotEmptyIsLazy()
         });
     }
 
+    public function testIsSingleIsLazy()
+    {
+        $this->assertEnumerates(2, function ($collection) {
+            $collection->isSingle();
+        });
+    }
+
     public function testJoinIsLazy()
     {
         $this->assertEnumeratesOnce(function ($collection) {