diff --git a/src/unit/engine/PytestTestEngine.php b/src/unit/engine/PytestTestEngine.php
index b104d8fc..8d3891b9 100644
--- a/src/unit/engine/PytestTestEngine.php
+++ b/src/unit/engine/PytestTestEngine.php
@@ -1,135 +1,144 @@
 <?php
 
 /**
  * Very basic 'py.test' unit test engine wrapper.
  */
 final class PytestTestEngine extends ArcanistUnitTestEngine {
 
   public function run() {
     $working_copy = $this->getWorkingCopy();
     $this->project_root = $working_copy->getProjectRoot();
 
     $junit_tmp = new TempFile();
     $cover_tmp = new TempFile();
 
     $future = $this->buildTestFuture($junit_tmp, $cover_tmp);
-    $future->resolvex();
+    list($err, $stdout, $stderr) = $future->resolve();
+
+    if (!Filesystem::pathExists($junit_tmp)) {
+      throw new CommandException(
+        "Command failed with error #{$err}!",
+        $future->getCommand(),
+        $err,
+        $stdout,
+        $stderr);
+    }
 
     $future = new ExecFuture('coverage xml -o %s', $cover_tmp);
     $future->setCWD($this->project_root);
     $future->resolvex();
 
     return $this->parseTestResults($junit_tmp, $cover_tmp);
   }
 
   public function buildTestFuture($junit_tmp, $cover_tmp) {
     $paths = $this->getPaths();
 
     $cmd_line = csprintf('py.test --junit-xml=%s', $junit_tmp);
 
     if ($this->getEnableCoverage() !== false) {
       $cmd_line = csprintf(
         'coverage run --source %s -m %C',
         $this->project_root,
         $cmd_line);
     }
 
     return new ExecFuture('%C', $cmd_line);
   }
 
   public function parseTestResults($junit_tmp, $cover_tmp) {
     $parser = new ArcanistXUnitTestResultParser();
     $results = $parser->parseTestResults(
       Filesystem::readFile($junit_tmp));
 
     if ($this->getEnableCoverage() !== false) {
       $coverage_report = $this->readCoverage($cover_tmp);
       foreach ($results as $result) {
           $result->setCoverage($coverage_report);
       }
     }
 
     return $results;
   }
 
   public function readCoverage($path) {
     $coverage_data = Filesystem::readFile($path);
     if (empty($coverage_data)) {
        return array();
     }
 
     $coverage_dom = new DOMDocument();
     $coverage_dom->loadXML($coverage_data);
 
     $paths = $this->getPaths();
     $reports = array();
     $classes = $coverage_dom->getElementsByTagName('class');
 
     foreach ($classes as $class) {
       // filename is actually python module path with ".py" at the end,
       // e.g.: tornado.web.py
       $relative_path = explode('.', $class->getAttribute('filename'));
       array_pop($relative_path);
       $relative_path = implode('/', $relative_path);
 
       // first we check if the path is a directory (a Python package), if it is
       // set relative and absolute paths to have __init__.py at the end.
       $absolute_path = Filesystem::resolvePath($relative_path);
       if (is_dir($absolute_path)) {
         $relative_path .= '/__init__.py';
         $absolute_path .= '/__init__.py';
       }
 
       // then we check if the path with ".py" at the end is file (a Python
       // submodule), if it is - set relative and absolute paths to have
       // ".py" at the end.
       if (is_file($absolute_path.'.py')) {
         $relative_path .= '.py';
         $absolute_path .= '.py';
       }
 
       if (!file_exists($absolute_path)) {
         continue;
       }
 
       if (!in_array($relative_path, $paths)) {
         continue;
       }
 
       // get total line count in file
       $line_count = count(file($absolute_path));
 
       $coverage = '';
       $start_line = 1;
       $lines = $class->getElementsByTagName('line');
       for ($ii = 0; $ii < $lines->length; $ii++) {
         $line = $lines->item($ii);
 
         $next_line = intval($line->getAttribute('number'));
         for ($start_line; $start_line < $next_line; $start_line++) {
             $coverage .= 'N';
         }
 
         if (intval($line->getAttribute('hits')) == 0) {
             $coverage .= 'U';
         }
         else if (intval($line->getAttribute('hits')) > 0) {
             $coverage .= 'C';
         }
 
         $start_line++;
       }
 
       if ($start_line < $line_count) {
         foreach (range($start_line, $line_count) as $line_num) {
           $coverage .= 'N';
         }
       }
 
       $reports[$relative_path] = $coverage;
     }
 
     return $reports;
   }
 
 }