diff --git a/src/CRM/CivixBundle/Test/CommandTester.php b/src/CRM/CivixBundle/Test/CommandTester.php
new file mode 100644
index 00000000..b42e490c
--- /dev/null
+++ b/src/CRM/CivixBundle/Test/CommandTester.php
@@ -0,0 +1,34 @@
+<?php
+
+namespace CRM\CivixBundle\Test;
+
+interface CommandTester {
+
+  /**
+   * Executes the command.
+   *
+   * Available execution options:
+   *
+   *  * interactive:               Sets the input interactive flag
+   *  * decorated:                 Sets the output decorated flag
+   *  * verbosity:                 Sets the output verbosity flag
+   *  * capture_stderr_separately: Make output of stdOut and stdErr separately available
+   *
+   * @param array $input An array of command arguments and options
+   * @param array $options An array of execution options
+   *
+   * @return int The command exit code
+   */
+  public function execute(array $input, array $options = []);
+
+  /**
+   * @return string
+   */
+  public function getDisplay(bool $normalize = FALSE);
+
+  /**
+   * @return int
+   */
+  public function getStatusCode();
+
+}
diff --git a/src/CRM/CivixBundle/Test/SubProcessCommandTester.php b/src/CRM/CivixBundle/Test/SubProcessCommandTester.php
new file mode 100644
index 00000000..fbb6b23e
--- /dev/null
+++ b/src/CRM/CivixBundle/Test/SubProcessCommandTester.php
@@ -0,0 +1,88 @@
+<?php
+
+namespace CRM\CivixBundle\Test;
+
+use Symfony\Component\Process\Process;
+
+class SubProcessCommandTester implements CommandTester {
+
+  /**
+   * @var array
+   */
+  protected $baseCommand;
+
+  /**
+   * @var string|null
+   */
+  protected $display;
+
+  /**
+   * @var int|null
+   */
+  protected $statusCode;
+
+  /**
+   * @param array $baseCommand
+   */
+  public function __construct(array $baseCommand) {
+    $this->baseCommand = $baseCommand;
+  }
+
+  /**
+   * Executes the command.
+   *
+   * @param array $input An array of command arguments and options
+   * @param array $options An array of execution options
+   *   Ignored
+   * @return int The command exit code
+   */
+  public function execute(array $input, array $options = []) {
+    if (!empty($options)) {
+      throw new \LogicException(__CLASS__ . " does not implement support for execute() options");
+    }
+
+    $command = $this->baseCommand;
+    foreach ($input as $key => $value) {
+      if (substr($key, 0, 2) === '--') {
+        if ($value === TRUE) {
+          $command[] = $key;
+        }
+        else {
+          $command[] = "$key=$value";
+        }
+      }
+      else {
+        $command[] = $value;
+      }
+    }
+
+    $buffer = fopen('php://memory', 'w+');
+
+    $p = new Process($command);
+    $p->run(function ($type, $data) use ($buffer) {
+      // Default policy - combine STDOUT and STDIN into one continuous stream.
+      fwrite($buffer, $data);
+    });
+    $this->statusCode = $p->getExitCode();
+
+    rewind($buffer);
+    $this->display = stream_get_contents($buffer);
+    fclose($buffer);
+
+    return $this->statusCode;
+  }
+
+  public function getDisplay(bool $normalize = FALSE) {
+    if ($normalize) {
+      return str_replace(\PHP_EOL, "\n", $this->display);
+    }
+    else {
+      return $this->display;
+    }
+  }
+
+  public function getStatusCode(): int {
+    return $this->statusCode;
+  }
+
+}
diff --git a/tests/e2e/CivixProjectTestTrait.php b/tests/e2e/CivixProjectTestTrait.php
index f09567d0..c388f7f7 100644
--- a/tests/e2e/CivixProjectTestTrait.php
+++ b/tests/e2e/CivixProjectTestTrait.php
@@ -2,8 +2,9 @@
 
 namespace E2E;
 
-use CRM\CivixBundle\Application;
 use CRM\CivixBundle\Generator;
+use CRM\CivixBundle\Test\CommandTester;
+use CRM\CivixBundle\Test\SubProcessCommandTester;
 use CRM\CivixBundle\Utils\Files;
 use CRM\CivixBundle\Utils\Path;
 use ProcessHelper\ProcessHelper as PH;
@@ -11,7 +12,6 @@
 use Symfony\Component\Console\Input\ArrayInput;
 use Symfony\Component\Console\Output\NullOutput;
 use Symfony\Component\Console\Output\StreamOutput;
-use Symfony\Component\Console\Tester\CommandTester;
 
 /**
  * Add this to a test-class to define an E2E test with a new civix-style extension/project.
@@ -71,11 +71,32 @@ public static function getExtPath(...$subpath): Path {
     return static::getWorkspacePath(...$subpath);
   }
 
-  public static function civix(string $command): CommandTester {
+  public static function civix(string $subCommand): CommandTester {
     \Civix::reset();
-    $application = new Application();
-    $command = $application->find($command);
-    return new CommandTester($command);
+
+    $isolation = getenv('CIVIX_TEST_ISOLATION') ?: 'on';
+
+    switch ($isolation) {
+      case 'on':
+        if (getenv('CIVIX_TEST_BINARY')) {
+          $baseCommand = [getenv('CIVIX_TEST_BINARY')];
+        }
+        else {
+          $baseCommand = ['php', (dirname(__DIR__, 2) . '/bin/civix')];
+        }
+        $baseCommand[] = $subCommand;
+        return new SubProcessCommandTester($baseCommand);
+
+      case 'off':
+        $application = new \CRM\CivixBundle\Application();
+        $command = $application->find($subCommand);
+        return new class ($command) extends \Symfony\Component\Console\Tester\CommandTester implements CommandTester {
+
+        };
+
+      default:
+        throw new \RuntimeException("Unrecognized value of CIVIX_TEST_BINARY. Specify on|off.");
+    }
   }
 
   public function civixGenerateModule(string $key, array $options = []): CommandTester {
@@ -85,7 +106,7 @@ public function civixGenerateModule(string $key, array $options = []): CommandTe
       '--enable' => 'false',
     ]);
     if ($tester->getStatusCode() !== 0) {
-      throw new \RuntimeException(sprintf("Failed to generate module (%s)", $key));
+      throw new \RuntimeException(sprintf("Failed to generate module (%s):\n%s", $key, $tester->getDisplay(TRUE)));
     }
     return $tester;
   }