Time travel

Carbon/Carbon.php

@@ -26,6 +26,8 @@ class Carbon extends \DateTime
    const MINUTES_PER_HOUR = 60;
    const SECONDS_PER_MINUTE = 60;
 
+   protected static $timeTravelOffsets = array();
+
    protected static function safeCreateDateTimeZone($object)
    {
       if ($object instanceof \DateTimeZone) {
@@ -43,10 +45,29 @@ protected static function safeCreateDateTimeZone($object)
 
    public function __construct($time = null, $tz = null)
    {
+      $datetime = count(static::$timeTravelOffsets) ? "now" : $time;
       if ($tz !== null) {
-         parent::__construct($time, self::safeCreateDateTimeZone($tz));
+         parent::__construct($datetime, self::safeCreateDateTimeZone($tz));
       } else {
-         parent::__construct($time);
+         parent::__construct($datetime);
+      }
+
+      if (!count(static::$timeTravelOffsets)) {
+          return;
+      }
+
+      foreach (static::$timeTravelOffsets as $offset) {
+         $this->addSeconds($offset);
+      }
+
+      $this->modify($time);
+
+      /**
+       * Hack for the "first day of january 2008"
+       */
+      $dt = new \DateTime($time);
+      if ("00:00:00" === $dt->format("H:i:s")) {
+         $this->setTime(0, 0, 0);
       }
    }
 
@@ -58,11 +79,12 @@ public static function instance(\DateTime $dt)
    public static function now($tz = null)
    {
       if ($tz !== null) {
-         return new self(null, self::safeCreateDateTimeZone($tz));
+         return new self("now", self::safeCreateDateTimeZone($tz));
       } else {
-         return new self();
+         return new self("now");
       }
    }
+
    public static function create($year = null, $month = null, $day = null, $hour = null, $minute = null, $second = null, $tz = null)
    {
       $year = ($year === null) ? date('Y') : $year;
@@ -112,6 +134,47 @@ public static function createFromTimestampUTC($timestamp)
       return new self('@'.$timestamp);
    }
 
+   public static function timeTravelTo($time, \Closure $callback = null)
+   {
+      $now = static::now();
+      if (!($time instanceof \DateTime)) {
+          $time = static::now()->modify($time);
+      }
+      static::$timeTravelOffsets[] = $time->getTimestamp() - $now->getTimestamp(); 
+
+      if (null === $callback) {
+         return;
+      }
+
+      try {
+         $return = $callback();
+         static::restorePreviousTime();
+         return $return;
+      } catch (\Exception $e) {
+         static::restorePreviousTime();
+         throw $e;
+      } 
+   }
+
+   public static function backToThePresent()
+   {
+      static::$timeTravelOffsets = array();
+   }
+
+   public static function nowWithoutTimeTravel($tz = null)
+   {
+      $offsets = static::$timeTravelOffsets;
+      static::$timeTravelOffsets = array();
+      $now = static::now($tz);
+      static::$timeTravelOffsets = $offsets;
+      return $now;
+   }
+
+   public static function restorePreviousTime()
+   {
+      array_pop(static::$timeTravelOffsets);
+   }
+
    public function copy()
    {
       return self::instance($this);

Carbon/Tests/TimeTravelTest.php

@@ -0,0 +1,154 @@
+<?php
+
+/*
+ * This file is part of the Carbon package.
+ *
+ * (c) Brian Nesbitt <brian@nesbot.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Carbon\Tests;
+
+use Carbon\Carbon;
+
+class TimeTravelTest extends TestFixture
+{
+    public function tearDown()
+    {
+        Carbon::backToThePresent();
+        parent::tearDown();
+    }
+
+    public function testTimeTravel()
+    {
+        Carbon::timeTravelTo("2 years ago");
+        $this->assertSame(date("Y") - 2, Carbon::now()->year);
+    }
+
+    public function testTimeTravelWithAbsolute()
+    {
+        Carbon::timeTravelTo("1999-12-31");
+        $this->assertSame(1999, Carbon::now()->year);
+    }
+
+    public function testConsecutiveTimeTravellingWithRelativeToTimeTravelTime()
+    {
+        Carbon::timeTravelTo("2 years ago");
+        Carbon::timeTravelTo("+5 years");
+        $this->assertSame(date("Y") + 3, Carbon::now()->year);
+    }
+
+    public function testTimeTravelWithConstructorAndNow()
+    {
+        Carbon::timeTravelTo("2 years ago");
+        $c = new Carbon("now");
+        $this->assertSame(date("Y") - 2, $c->year);
+    }
+
+    public function testTimeTravelWithConstructorAndAbsolute()
+    {
+        Carbon::timeTravelTo("2 years ago");
+        $c = new Carbon("1999/12/12");
+        $this->assertSame(1999, $c->year);
+    }
+
+    public function testTimeTravelWithConstructorAndRelative()
+    {
+        Carbon::timeTravelTo("2 years ago");
+        $c = new Carbon("2 years ago");
+        $this->assertSame(date("Y") - 4, $c->year);
+    }
+
+    public function testTimeTravelWithConstructorAndComplex()
+    {
+        Carbon::timeTravelTo("2 years ago");
+        $c = new Carbon("first day of january 2008");
+        $this->assertCarbon($c, 2008, 1, 1, 0, 0, 0);
+    }
+
+    public function testTimeTravelWithConstructorAndComplexToday()
+    {
+        Carbon::timeTravelTo("2 years ago");
+        $c = new Carbon("today");
+        $this->assertCarbon($c, $c->year, $c->month, $c->day, 0, 0, 0);
+    }
+
+    public function testTimeTravelWithConstructorAndComplexNoon()
+    {
+        Carbon::timeTravelTo("2 years ago");
+        $c = new Carbon("noon");
+        $this->assertCarbon($c, $c->year, $c->month, $c->day, 12, 0, 0);
+    }
+
+    public function testRestorePreviousTime()
+    {
+        Carbon::timeTravelTo("2 years ago");
+        Carbon::timeTravelTo("+5 years");
+        Carbon::timeTravelTo("+7 years");
+        Carbon::restorePreviousTime();
+        Carbon::restorePreviousTime();
+        $this->assertSame(date("Y") - 2, Carbon::now()->year);
+    }
+
+    public function testTimeTravelToWithClosure()
+    {
+        $that = $this;
+        Carbon::timeTravelTo("1999-10-10", function() use ($that) {
+            $that->assertSame(1999, Carbon::now()->year);
+        });
+        $this->assertSame(intval(date("Y")), Carbon::now()->year);
+    }
+
+    public function testTimeTravelToWithClosureGetsReturnValue()
+    {
+        $ret = Carbon::timeTravelTo("1999-10-10", function() {
+            return 123;
+        });
+        $this->assertSame(123, $ret);
+    }
+
+    public function testTimeTravelToWithClosureRestoresDespiteException()
+    {
+        try {
+            Carbon::timeTravelTo("1999-10-10", function() {
+                throw new \Exception("waaa");
+            });
+        } catch (\Exception $e) { 
+            // noop
+        }
+        $this->assertSame(intval(date("Y")), Carbon::now()->year);
+    }
+
+    public function testBackToThePresent()
+    {
+        Carbon::timeTravelTo("2 years ago");
+        Carbon::backToThePresent();
+        $this->assertSame(intval(date("Y")), Carbon::now()->year);
+    }
+
+    public function testBackToThePresentAfterNoJumps()
+    {
+        Carbon::backToThePresent();
+        $this->assertSame(intval(date("Y")), Carbon::now()->year);
+    }
+
+    public function testBackToThePresentAfterSeveralJumps()
+    {
+        Carbon::timeTravelTo("2 years ago");
+        Carbon::timeTravelTo("+5 years");
+        Carbon::timeTravelTo("+7 years");
+        Carbon::backToThePresent();
+        $this->assertSame(intval(date("Y")), Carbon::now()->year);
+    }
+
+    public function testNowWithTimeTravel()
+    {
+        Carbon::timeTravelTo("2 years ago");
+        Carbon::timeTravelTo("+5 years");
+        Carbon::timeTravelTo("+7 years");
+        $this->assertSame(intval(date("Y")), Carbon::nowWithoutTimeTravel()->year);
+    }
+
+}

readme.md

@@ -56,6 +56,7 @@ $daysSinceEpoch = Carbon::createFromTimeStamp(0)->diffInDays();
     * [Difference](#api-difference)
     * [Difference for Humans](#api-humandiff)
     * [Constants](#api-constants)
+    * [Time Travel](#time-travel)
 * [About](#about)
     * [Contributing](#about-contributing)
     * [Author](#about-author)
@@ -544,6 +545,53 @@ if ($dt->dayOfWeek === Carbon::SATURDAY) {
 }
 ```
 
+<a name="time-travel"/>
+### Time Travel
+
+There's an experimental time travelling feature for testing purposes, ala [ruby's delorean](https://github.com/bebanjo/delorean)
+
+```php
+class SeasonalProduct
+{ 
+    protected $price;
+
+    public function __construct($price)
+    {
+        $this->price = $price;
+    }
+
+    public function getPrice() {
+        $multiplier = 1;
+        if (Carbon::now()->month == 12) {
+            $multiplier = 2;
+        }
+
+        return $this->price * $multiplier;
+    }
+}
+
+$product = new SeasonalProduct(100);
+Carbon::timeTravelTo("november");
+echo $product->getPrice();                         // 100
+Carbon::timeTravelTo("december"); 
+echo $product->getPrice();                         // 200
+Carbon::restorePreviousTime(); 
+echo $product->getPrice();                         // 100
+
+// reset 
+Carbon::timeTravelTo("december");
+Carbon::backToThePresent();
+echo $product->getPrice();                         // 100
+
+// with a callback
+$callback = Carbon::timeTravelTo("december", function() use ($product) {
+    return $product->getPrice();
+});
+echo $callback;                                    // 200
+echo $product->getPrice();                         // 100
+
+```
+
 <a name="about"/>
 ## About
 
@@ -612,4 +660,4 @@ Carbon is licensed under the MIT License - see the `LICENSE` file for details
 <a name="about-whyname"/>
 ### Why the name Carbon?
 
-Read about [Carbon Dating](http://en.wikipedia.org/wiki/Radiocarbon_dating)
+Read about [Carbon Dating](http://en.wikipedia.org/wiki/Radiocarbon_dating)