Added support for exception handlers that return promises.

Upgraded amp minimum version from 2.0 -> 2.1 to fix timer issue #243.

Author: Bilge

composer.json

@@ -17,7 +17,7 @@
   },
   "require-dev": {
     "phpunit/phpunit": "^4.8",
-    "amphp/amp": "^2"
+    "amphp/amp": "^2.1"
   },
   "autoload": {
     "files": [

src/retry.php

@@ -22,7 +22,8 @@
 function retry($tries, callable $operation, callable $onError = null)
 {
     /** @var \Generator $generator */
-    $generator = (static function () use ($tries, $operation, $onError) {
+    $generator = (static function () use ($tries, $operation, $onError): \Generator {
+        // Nothing to do if tries less than or equal to zero.
         if (($tries |= 0) <= $attempts = 0) {
             return;
         }
@@ -39,8 +40,14 @@ function retry($tries, callable $operation, callable $onError = null)
                 throw new FailingTooHardException($attempts, $exception);
             }
 
-            if ($onError && $onError($exception) === false) {
-                return;
+            if ($onError) {
+                if (($result = $onError($exception)) instanceof Promise) {
+                    $result = yield $result;
+                }
+
+                if ($result === false) {
+                    return;
+                }
             }
 
             goto beginning;

test/RetryAsyncTest.php

@@ -2,6 +2,8 @@
 namespace ScriptFUSIONTest\Retry;
 
 use Amp\Delayed;
+use Amp\Promise;
+use Amp\Success;
 use ScriptFUSION\Retry\FailingTooHardException;
 
 final class RetryAsyncTest extends \PHPUnit_Framework_TestCase
@@ -94,7 +96,7 @@ public function testFailingTooHardAsync()
     }
 
     /**
-     * These that the error callback is called before each retry.
+     * Tests that the error callback is called before each retry.
      */
     public function testErrorCallbackAsync()
     {
@@ -120,13 +122,37 @@ public function testErrorCallbackAsync()
     }
 
     /**
-     * Tests that an error handler that returns false aborts retrying.
+     * Tests that an error callback that returns a promise has its promise resolved.
+     */
+    public function testPromiseErrorCallback()
+    {
+        $delay = 250; // Quarter of a second.
+        $start = microtime(true);
+
+        try {
+            \Amp\Promise\wait(
+                \ScriptFUSION\Retry\retryAsync($tries = 3, static function () {
+                    throw new \DomainException;
+                }, static function () use ($delay): Promise {
+                    return new Delayed($delay);
+                })
+            );
+        } catch (FailingTooHardException $outerException) {
+            self::assertInstanceOf(\DomainException::class, $outerException->getPrevious());
+        }
+
+        self::assertTrue(isset($outerException));
+        self::assertGreaterThan($start + $delay * ($tries - 1) / 1000, microtime(true));
+    }
+
+    /**
+     * Tests that when error handler that returns false, it aborts retrying.
      */
     public function testErrorCallbackHaltAsync()
     {
         $invocations = 0;
 
-        \ScriptFUSION\Retry\retryAsync($tries = 2, static function () use (&$invocations) {
+        \ScriptFUSION\Retry\retryAsync(2, static function () use (&$invocations) {
             ++$invocations;
 
             throw new \RuntimeException;
@@ -136,4 +162,36 @@ public function testErrorCallbackHaltAsync()
 
         self::assertSame(1, $invocations);
     }
+
+    /**
+     * Tests that when an error handler returns a promise that false, it aborts retrying.
+     */
+    public function testPromiseErrorCallbackHaltAsync()
+    {
+        $invocations = 0;
+
+        \ScriptFUSION\Retry\retryAsync(2, static function () use (&$invocations) {
+            ++$invocations;
+
+            throw new \RuntimeException;
+        }, static function (): Promise {
+            return new Success(false);
+        });
+
+        self::assertSame(1, $invocations);
+    }
+
+    /**
+     * Tests that the exception handler can throw an exception that will not be caught.
+     */
+    public function testErrorCallbackCanThrow()
+    {
+        $this->setExpectedException(\LogicException::class);
+
+        \ScriptFUSION\Retry\retryAsync(2, static function () {
+            throw new \RuntimeException;
+        }, static function () {
+            throw new \LogicException;
+        });
+    }
 }