Add 'unless' method to collections (inverse of 'when') (#19740)

src/Illuminate/Support/Collection.php

@@ -384,6 +384,19 @@ public function when($value, callable $callback, callable $default = null)
         return $this;
     }
 
+    /**
+     * Apply the callback if the value is falsy.
+     *
+     * @param  bool  $value
+     * @param  callable  $callback
+     * @param  callable  $default
+     * @return mixed
+     */
+    public function unless($value, callable $callback, callable $default = null)
+    {
+        return $this->when(! $value, $callback, $default);
+    }
+
     /**
      * Filter items by the given key value pair.
      *

tests/Support/SupportCollectionTest.php

@@ -2121,6 +2121,38 @@ public function testWhenDefault()
 
         $this->assertSame(['michael', 'tom', 'taylor'], $collection->toArray());
     }
+
+    public function testUnless()
+    {
+        $collection = new Collection(['michael', 'tom']);
+
+        $collection->unless(false, function ($collection) {
+            return $collection->push('caleb');
+        });
+
+        $this->assertSame(['michael', 'tom', 'caleb'], $collection->toArray());
+
+        $collection = new Collection(['michael', 'tom']);
+
+        $collection->unless(true, function ($collection) {
+            return $collection->push('caleb');
+        });
+
+        $this->assertSame(['michael', 'tom'], $collection->toArray());
+    }
+
+    public function testUnlessDefault()
+    {
+        $collection = new Collection(['michael', 'tom']);
+
+        $collection->unless(true, function ($collection) {
+            return $collection->push('caleb');
+        }, function ($collection) {
+            return $collection->push('taylor');
+        });
+
+        $this->assertSame(['michael', 'tom', 'taylor'], $collection->toArray());
+    }
 }
 
 class TestSupportCollectionHigherOrderItem