Handle revert errors better (#6)

* Catch and wrap up failures in applying compensation steps

CHANGELOG.md

@@ -8,6 +8,18 @@
 
 ### Backwards incompatible changes
 
+## v0.3.0 (2019-04-18)
+
+### Enhancements
+* Failures from applying compensations are caught allowing the process
+to continue and are thrown at the end instead. 
+
+### Bug fixes
+None
+
+### Backwards incompatible changes
+None
+
 ## v0.2.0 (2018-06-28)
 
 ### Enhancements

src/Exceptions/FailedApplyingAllCompensations.php

@@ -0,0 +1,28 @@
+<?php
+
+
+namespace MeadSteve\Tale\Exceptions;
+
+use Throwable;
+
+class FailedApplyingAllCompensations extends \RuntimeException implements TaleException
+{
+    /**
+     * @var Throwable[]
+     */
+    public $caughtExceptions;
+
+    /**
+     * FailedApplyingAllCompensations constructor.
+     * @param \Throwable[] $caughtExceptions
+     */
+    public function __construct($caughtExceptions)
+    {
+        $previous = null;
+        if (sizeof($caughtExceptions) == 1) {
+            $previous = $caughtExceptions[0];
+        }
+        parent::__construct("Failed applying all compensation steps", 0, $previous);
+        $this->caughtExceptions = $caughtExceptions;
+    }
+}

src/Transaction.php

@@ -2,6 +2,7 @@
 
 namespace MeadSteve\Tale;
 
+use MeadSteve\Tale\Exceptions\FailedApplyingAllCompensations;
 use MeadSteve\Tale\Execution\CompletedStep;
 use MeadSteve\Tale\Execution\Failure;
 use MeadSteve\Tale\Execution\Success;
@@ -87,12 +88,20 @@ private function addStep(Step $step): Transaction
      */
     private function revertCompletedSteps(array $completedSteps): void
     {
+        $errors = [];
         foreach (array_reverse($completedSteps) as $completedStep) {
-            $step = $completedStep->step;
-            $stepId = $completedStep->stepId;
-            $this->logger->debug("Compensating for step {$this->stepName($step)} [{$stepId}]");
-            $step->compensate($completedStep->state);
-            $this->logger->debug("Compensation complete for step {$this->stepName($step)} [{$stepId}]");
+            try {
+                $step = $completedStep->step;
+                $stepId = $completedStep->stepId;
+                $this->logger->debug("Compensating for step {$this->stepName($step)} [{$stepId}]");
+                $step->compensate($completedStep->state);
+                $this->logger->debug("Compensation complete for step {$this->stepName($step)} [{$stepId}]");
+            } catch (\Throwable $error) {
+                $errors[] = $error;
+            }
+        }
+        if (sizeof($errors) !== 0) {
+            throw new FailedApplyingAllCompensations($errors);
         }
     }
 

tests/Steps/Mocks/StepWithFailingCompensate.php

@@ -0,0 +1,30 @@
+<?php
+
+namespace MeadSteve\Tale\Tests\Steps\Mocks;
+
+use MeadSteve\Tale\Steps\NamedStep;
+
+class StepWithFailingCompensate implements NamedStep
+{
+    public function execute($state)
+    {
+        return $state;
+    }
+
+    /**
+     * @param mixed $state
+     * @throws \Exception
+     */
+    public function compensate($state): void
+    {
+        throw new \Exception("I failed compensating");
+    }
+
+    /**
+     * @return string the public name of this step
+     */
+    public function stepName(): string
+    {
+        return "step with failing compensation";
+    }
+}

tests/TransactionTest.php

@@ -3,11 +3,13 @@
 namespace MeadSteve\Tale\Tests;
 
 use Gamez\Psr\Log\TestLogger;
+use MeadSteve\Tale\Exceptions\FailedApplyingAllCompensations;
 use MeadSteve\Tale\Execution\Failure;
 use MeadSteve\Tale\Steps\LambdaStep;
 use MeadSteve\Tale\Tests\Steps\Mocks\FailingStep;
 use MeadSteve\Tale\Tests\Steps\Mocks\MockFinalisingStep;
 use MeadSteve\Tale\Tests\Steps\Mocks\MockStep;
+use MeadSteve\Tale\Tests\Steps\Mocks\StepWithFailingCompensate;
 use MeadSteve\Tale\Transaction;
 use PHPUnit\Framework\TestCase;
 
@@ -176,4 +178,25 @@ public function testProvidedLoggerGetsSomeDebugLogs()
 
         $this->assertTrue($mockLogger->log->countRecordsWithLevel("debug") > 0);
     }
+
+    public function testFailuresInCompensationAreCaught()
+    {
+
+        $firstStep = new MockStep();
+        $transaction = (new Transaction())
+            ->add($firstStep)
+            ->add(new StepWithFailingCompensate())
+            ->add(new FailingStep());
+
+        $this->expectException(FailedApplyingAllCompensations::class);
+        $this->expectExceptionMessage("Failed applying all compensation steps");
+
+        try {
+            $transaction->run("some payload");
+        } finally {
+            # The reverted state should not be null as it should have
+            # been compensated
+            $this->assertNotNull($firstStep->revertedState);
+        }
+    }
 }