Let TestEngine know if the command that triggered tests is 'arc diff' or 'arc

unit'

Summary:
We want to handle 'arc unit' and 'arc diff' differently in our test
framework.

Test Plan:
Tested that with 'arc unit' the value was set to 'unit' and with 'arc diff'
the value was set to 'diff'.

Reviewed By: epriestley
Reviewers: slawekbiel, epriestley
CC: jungejason, grglr, aran, tuomaspelkonen, epriestley
Differential Revision: 430

src/unit/engine/base/ArcanistBaseUnitTestEngine.php

@@ -27,6 +27,7 @@ abstract class ArcanistBaseUnitTestEngine {
   private $paths;
   private $arguments = array();
   protected $diffID;
+  private $enableAsyncTests;
 
   final public function __construct() {
 
@@ -61,6 +62,14 @@ abstract class ArcanistBaseUnitTestEngine {
     return idx($this->arguments, $key, $default);
   }
 
+  final public function setEnableAsyncTests($enable_async_tests) {
+    $this->enableAsyncTests = $enable_async_tests;
+  }
+
+  final public function getEnableAsyncTests() {
+    return $this->enableAsyncTests;
+  }
+
   abstract public function run();
 
   /**

src/workflow/unit/ArcanistUnitWorkflow.php

@@ -99,6 +99,13 @@ EOTEXT
     $this->engine->setPaths($paths);
     $this->engine->setArguments($this->getPassthruArgumentsAsMap('unit'));
 
+    // Enable possible async tests only for 'arc diff' not 'arc unit'
+    if ($this->getParentWorkflow()) {
+      $this->engine->setEnableAsyncTests(true);
+    } else {
+      $this->engine->setEnableAsyncTests(false);
+    }
+
     $results = $this->engine->run();
 
     $status_codes = array(