Make physical quantity serializable to JSON

composer.json

@@ -27,7 +27,8 @@
     },
 
     "require": {
-        "php": ">=5.5.0"
+        "php": ">=5.5.0",
+        "ext-json": "*"
     },
 
     "require-dev": {

source/AbstractPhysicalQuantity.php

@@ -1,7 +1,7 @@
 <?php
 namespace PhpUnitsOfMeasure;
 
-abstract class AbstractPhysicalQuantity implements PhysicalQuantityInterface
+abstract class AbstractPhysicalQuantity implements PhysicalQuantityInterface, \JsonSerializable
 {
     /**
      * The collection of units in which this quantity can be represented.
@@ -189,6 +189,19 @@ public function __toString()
         return trim($this->originalValue . ' ' . static::getUnit($this->originalUnit)->getName());
     }
 
+    /**
+     * {@inheritdoc}
+     *
+     * @return array
+     */
+    public function jsonSerialize()
+    {
+        return [
+            'value' => $this->originalValue,
+            'unit' => static::getUnit($this->originalUnit)->getName(),
+        ];
+    }
+
     /**
      * @see \PhpUnitsOfMeasure\PhysicalQuantityInterface::add
      */

tests/AbstractPhysicalQuantityTest.php

@@ -141,6 +141,15 @@ public function testToString(AbstractPhysicalQuantity $value, $string)
         $this->assertSame($string, (string) $value);
     }
 
+    /**
+     * @dataProvider jsonSerializeProvider
+     * @covers \PhpUnitsOfMeasure\AbstractPhysicalQuantity::jsonSerialize
+     */
+    public function testJsonSerialize(AbstractPhysicalQuantity $value, $serialized)
+    {
+        $this->assertSame($serialized, json_decode(json_encode($value), true));
+    }
+
     /**
      *
      * @dataProvider quantityConversionsProvider
@@ -308,6 +317,23 @@ public function toStringProvider()
         ];
     }
 
+    /**
+     * Provide some string conversion testing data
+     * 1) The object which will be json serialized
+     * 2) the expected resulting array from the conversion
+     */
+    public function jsonSerializeProvider()
+    {
+        return [
+            [new Wonkicity(2, 'u'), ['value' => 2, 'unit' => 'u']],
+            [new Wonkicity(2, 'uvee'), ['value' => 2, 'unit' => 'u']],
+            [new Wonkicity(2, 'v'), ['value' => 2, 'unit' => 'v']],
+            [new Wonkicity(2, 'vorps'), ['value' => 2, 'unit' => 'v']],
+            [new Woogosity(2, 'plurps'), ['value' => 2, 'unit' => 'p']],
+            [new Woogosity(2, 'millilupees'), ['value' => 2, 'unit' => 'ml']],
+        ];
+    }
+
     /**
      * Provide some arithmetic relations for testing
      * 1) Boolean - whether or not the operation shoul error out due to a type mismatch (PhysicalQuantityMismatch exception)