fix(exec): stop failing asynchronous hooks with an empty error message

src/Automate/Command/ExecCommand.php

@@ -19,6 +19,7 @@
 use Symfony\Component\Console\Input\InputArgument;
 use Symfony\Component\Console\Input\InputInterface;
 use Symfony\Component\Console\Input\InputOption;
+use Symfony\Component\Console\Output\ConsoleOutputInterface;
 use Symfony\Component\Console\Output\OutputInterface;
 use Symfony\Component\Console\Style\SymfonyStyle;
 
@@ -57,7 +58,11 @@ protected function execute(InputInterface $input, OutputInterface $output): int
             $rs = $ssh->exec($command);
             $output->write($rs);
         } catch (\Exception $exception) {
-            $output->write($exception->getMessage());
+            // the parent process reports the failure of an asynchronous hook
+            // from the error output: writing there is what makes the reason
+            // visible instead of an empty error
+            $errorOutput = $output instanceof ConsoleOutputInterface ? $output->getErrorOutput() : $output;
+            $errorOutput->write($exception->getMessage());
 
             return Command::FAILURE;
         }

src/Automate/Workflow/Context.php

@@ -17,6 +17,7 @@
 use Automate\Model\Project;
 use Automate\Ssh\SshFactory;
 use Symfony\Component\Filesystem\Path;
+use Symfony\Component\Process\Process;
 
 class Context
 {
@@ -116,11 +117,27 @@ public function execAsync(string $command, ?array $serversList = null, bool $add
         foreach ($process as $child) {
             $child->wait();
             if (!$child->isSuccessful()) {
-                throw new \RuntimeException($child->getErrorOutput());
+                throw new \RuntimeException($this->getProcessError($child));
             }
         }
     }
 
+    /**
+     * Not every failure reaches the error output: fall back on the standard
+     * output, then on the exit code, so the deployment never stops on an empty
+     * error message.
+     */
+    private function getProcessError(Process $process): string
+    {
+        foreach ([$process->getErrorOutput(), $process->getOutput()] as $output) {
+            if ('' !== trim($output)) {
+                return trim($output);
+            }
+        }
+
+        return sprintf('The command failed with exit code %s.', $process->getExitCode() ?? 'unknown');
+    }
+
     /**
      * @param ?string[] $exclude
      * @param ?string[] $serversList

tests/Automate/Workflow/ContextTest.php

@@ -0,0 +1,92 @@
+<?php
+
+/*
+ * This file is part of the Automate package.
+ *
+ * (c) Julien Jacottet <jjacottet@gmail.com>
+ *
+ * For the full copyright and license information, please view the LICENSE
+ * file that was distributed with this source code.
+ */
+
+namespace Automate\Tests\Workflow;
+
+use Automate\Archiver;
+use Automate\Logger\LoggerInterface;
+use Automate\Model\Platform;
+use Automate\Model\Project;
+use Automate\Model\Server;
+use Automate\Ssh\Ssh;
+use Automate\Ssh\SshFactory;
+use Automate\Tests\AbstractMockTestCase;
+use Automate\Workflow\Context;
+use PHPUnit\Framework\Attributes\DataProvider;
+use Symfony\Component\Process\Process;
+
+class ContextTest extends AbstractMockTestCase
+{
+    /**
+     * @return iterable<string, array{string, string}>
+     */
+    public static function failingCommandProvider(): iterable
+    {
+        yield 'reported on the error output' => ['echo "boom" >&2; exit 1', 'boom'];
+
+        // this is how the "exec" command reports a failure
+        yield 'reported on the standard output' => ['echo "boom"; exit 1', 'boom'];
+
+        yield 'not reported at all' => ['exit 3', 'The command failed with exit code 3.'];
+    }
+
+    #[DataProvider('failingCommandProvider')]
+    public function testExecAsyncReportsWhyTheCommandFailed(string $script, string $expected): void
+    {
+        $context = $this->createContext(static fn (): Process => new Process(['sh', '-c', $script]));
+
+        $this->expectException(\RuntimeException::class);
+        $this->expectExceptionMessage($expected);
+
+        $context->execAsync('a command');
+    }
+
+    public function testExecAsyncSucceeds(): void
+    {
+        $context = $this->createContext(static fn (): Process => new Process(['sh', '-c', 'exit 0']));
+
+        $context->execAsync('a command');
+
+        $this->addToAssertionCount(1);
+    }
+
+    /**
+     * @param callable(): Process $process
+     */
+    private function createContext(callable $process): Context
+    {
+        $platform = new Platform('production');
+        $sshFactory = \Mockery::mock(SshFactory::class);
+
+        // two servers, otherwise execAsync falls back on the synchronous path
+        foreach (['front-01', 'front-02'] as $name) {
+            $server = (new Server())->setName($name)->setPath('/home/wwwroot/demo');
+            $platform->addServer($server);
+
+            $ssh = \Mockery::spy(Ssh::class);
+            $ssh->shouldReceive('execAsync')->andReturnUsing($process);
+            $sshFactory->shouldReceive('create')->with($server)->andReturns($ssh);
+        }
+
+        $context = new Context(
+            new Project(),
+            $platform,
+            \Mockery::spy(LoggerInterface::class),
+            $sshFactory,
+            \Mockery::mock(Archiver::class),
+            releaseId: '2024.03.10-2340.241'
+        );
+
+        $context->connect();
+
+        return $context;
+    }
+}