diff --git a/src/unit/engine/PhutilUnitTestEngine.php b/src/unit/engine/PhutilUnitTestEngine.php
--- a/src/unit/engine/PhutilUnitTestEngine.php
+++ b/src/unit/engine/PhutilUnitTestEngine.php
@@ -17,16 +17,21 @@
     }
 
     if (!$run_tests) {
-      throw new ArcanistNoEffectException('No tests to run.');
+      throw new ArcanistNoEffectException(pht('No tests to run.'));
     }
 
     $enable_coverage = $this->getEnableCoverage();
+
     if ($enable_coverage !== false) {
       if (!function_exists('xdebug_start_code_coverage')) {
         if ($enable_coverage === true) {
           throw new ArcanistUsageException(
-            'You specified --coverage but xdebug is not available, so '.
-            'coverage can not be enabled for PhutilUnitTestEngine.');
+            pht(
+              'You specified %s but %s is not available, so '.
+              'coverage can not be enabled for %s.',
+              '--coverage',
+              'XDebug',
+              __CLASS__));
         }
       } else {
         $enable_coverage = true;
@@ -134,17 +139,15 @@
         // does not actually lie within the library.
         continue;
       } else if (is_file($path) && preg_match('/\b__tests__\b/', $path)) {
-
         $look_here[$library_name.':'.$library_path] = array(
           'library' => $library_name,
           'path'    => $library_path,
         );
       } else {
         do {
-          var_dump($library_path);
           $look_here[$library_name.':'.$library_path] = array(
             'library' => $library_name,
-            'path'    => $library_path,
+            'path'    => $library_path == $library_root ? '' : $library_path,
           );
           $library_path = dirname($library_path);
         } while ($library_path != '.' && $library_path == $library_root);
@@ -159,7 +162,7 @@
     // "infrastructure/". However, "infrastructure/concrete/rebar/__tests__/"
     // defines more specific tests that run only when rebar/ (or some
     // subdirectory) changes.
-var_dump($look_here);
+
     $run_tests = array();
     foreach ($look_here as $path_info) {
       $library = $path_info['library'];
@@ -168,7 +171,7 @@
       $symbols = id(new PhutilSymbolLoader())
         ->setType('class')
         ->setLibrary($library)
-        ->setPathPrefix(($path ? $path.'/' : '').'__tests__/')
+        ->setPathPrefix($path)
         ->setAncestorClass('ArcanistPhutilTestCase')
         ->setConcreteOnly(true)
         ->selectAndLoadSymbols();