Print a more useful error message if any PHPUnit tests crash

Summary:
Before, if PHPUnit crashed (syntax error, undefined constant, etc), you would get a relatively unhelpful error message:

    firehed@Eric-Sterns-Mac-Pro ~/dev/php-lcd: arc unit
    Exception
    Clover coverage XML report file is empty, it probably means that phpunit failed to run tests. Try running arc unit with --trace option and then run generated phpunit command yourself, you might get the answer.
    (Run with --trace for a full exception trace.)

This now checks the json and code coverage reports and tries to pull a useful error message:

  firehed@Eric-Sterns-Mac-Pro ~/dev/php-lcd: arc unit
  Exception
  The test '/Users/firehed/dev/php-lcd/tests/PlateButtonsTest.php' crashed with the following output:

  Fatal error: Undefined class constant 'EFT' in /Users/firehed/dev/php-lcd/tests/PlateButtonsTest.php on line 25

  Call Stack:
  	0.0002     233104   1. {main}() /Users/firehed/dev/php-lcd/vendor/phpunit/phpunit/composer/bin/phpunit:0
  	0.0039     564872   2. PHPUnit_TextUI_Command::main() /Users/firehed/dev/php-lcd/vendor/phpunit/phpunit/composer/bin/phpunit:63
  	0.0039     565496   3. PHPUnit_TextUI_Command->run() /Users/firehed/dev/php-lcd/vendor/phpunit/phpunit/PHPUnit/TextUI/Command.php:129
  	0.0247    2280168   4. PHPUnit_TextUI_TestRunner->doRun() /Users/firehed/dev/php-lcd/vendor/phpunit/phpunit/PHPUnit/TextUI/Command.php:176
  	0.0293    2730760   5. PHPUnit_Framework_TestSuite->run() /Users/firehed/dev/php-lcd/vendor/phpunit/phpunit/PHPUnit/TextUI/TestRunner.php:349
  	0.1211    3996832   6. PHPUnit_Framework_TestSuite->runTest() /Users/firehed/dev/php-lcd/vendor/phpunit/phpunit/PHPUnit/Framework/TestSuite.php:745
  	0.1211    3996832   7. PHPUnit_Framework_TestCase->run() /Users/firehed/dev/php-lcd/vendor/phpunit/phpunit/PHPUnit/Framework/TestSuite.php:775
  	0.1211    3996832   8. PHPUnit_Framework_TestResult->run() /Users/firehed/dev/php-lcd/vendor/phpunit/phpunit/PHPUnit/Framework/TestCase.php:783
  	0.1233    3999752   9. PHPUnit_Framework_TestCase->runBare() /Users/firehed/dev/php-lcd/vendor/phpunit/phpunit/PHPUnit/Framework/TestResult.php:648
  	0.1236    4016432  10. PHPUnit_Framework_TestCase->runTest() /Users/firehed/dev/php-lcd/vendor/phpunit/phpunit/PHPUnit/Framework/TestCase.php:838
  	0.1237    4017240  11. ReflectionMethod->invokeArgs() /Users/firehed/dev/php-lcd/vendor/phpunit/phpunit/PHPUnit/Framework/TestCase.php:983
  	0.1237    4017520  12. Firehed\PlateButtonsTest->testSingleButtonOnButtonDown() /Users/firehed/dev/php-lcd/vendor/phpunit/phpunit/PHPUnit/Framework/TestCase.php:983

  (Run with --trace for a full exception trace.)

Or if nothing was written to `stderr`, you may get something like this:

  firehed@Eric-Sterns-Mac-Pro ~/dev/php-lcd: arc unit --no-coverage
  Exception
  Test Firehed\PlateButtonsTest::testSingleButtonOnButtonDown did not finish
  (Run with --trace for a full exception trace.)

Test Plan:
`arc unit` for arcanist itself
`arc unit` before and after the change on a project where:
* all tests pass
* some tests are failing
* a test causes a fatal error (undefined constant, bad method call, etc)
* a test file is invalid (syntax error)

No regressions that I could find, and all crashes now display a more useful error.

Reviewers: #blessed_reviewers, epriestley

Reviewed By: epriestley

CC: aurelijus, epriestley, aran

Differential Revision: https://secure.phabricator.com/D7848

src/unit/ArcanistUnitTestResult.php

@@ -14,7 +14,6 @@ final class ArcanistUnitTestResult {
   const RESULT_UNSOUND      = 'unsound';
   const RESULT_POSTPONED    = 'postponed';
 
-  private $namespace;
   private $name;
   private $link;
   private $result;

src/unit/engine/ArcanistBaseTestResultParser.php

@@ -8,6 +8,7 @@ abstract class ArcanistBaseTestResultParser {
   protected $enableCoverage;
   protected $projectRoot;
   protected $coverageFile;
+  protected $stderr;
 
   public function setEnableCoverage($enable_coverage) {
     $this->enableCoverage = $enable_coverage;
@@ -33,6 +34,11 @@ abstract class ArcanistBaseTestResultParser {
     return $this;
   }
 
+  public function setStderr($stderr) {
+    $this->stderr = $stderr;
+    return $this;
+  }
+
   /**
    * Parse test results from provided input and return an array
    * of ArcanistUnitTestResult

src/unit/engine/PhpunitResultParser.php

@@ -23,6 +23,14 @@ final class PhpunitResultParser extends ArcanistBaseTestResultParser {
    */
   public function parseTestResults($path, $test_results) {
 
+    if (!$test_results) {
+      $result = id(new ArcanistUnitTestResult())
+        ->setName($path)
+        ->setUserData($this->stderr)
+        ->setResult(ArcanistUnitTestResult::RESULT_BROKEN);
+      return array($result);
+    }
+
     $report = $this->getJsonReport($test_results);
 
     // coverage is for all testcases in the executed $path
@@ -33,8 +41,14 @@ final class PhpunitResultParser extends ArcanistBaseTestResultParser {
 
     $results = array();
     foreach ($report as $event) {
-      if ('test' != $event->event) {
-        continue;
+      switch ($event->event) {
+      case 'test':
+        break;
+      case 'testStart':
+        $lastTestFinished = false;
+        // fall through
+        default:
+          continue 2; // switch + loop
       }
 
       $status = ArcanistUnitTestResult::RESULT_PASS;
@@ -72,8 +86,15 @@ final class PhpunitResultParser extends ArcanistBaseTestResultParser {
       $result->setUserData($user_data);
 
       $results[] = $result;
+      $lastTestFinished = true;
     }
 
+    if (!$lastTestFinished) {
+      $results[] = id(new ArcanistUnitTestResult())
+        ->setName($event->test) // use last event
+        ->setUserData($this->stderr)
+        ->setResult(ArcanistUnitTestResult::RESULT_BROKEN);
+    }
     return $results;
   }
 
@@ -85,12 +106,7 @@ final class PhpunitResultParser extends ArcanistBaseTestResultParser {
   private function readCoverage() {
     $test_results = Filesystem::readFile($this->coverageFile);
     if (empty($test_results)) {
-      throw new Exception('Clover coverage XML report file is empty, '
-        . 'it probably means that phpunit failed to run tests. '
-        . 'Try running arc unit with --trace option and then run '
-        . 'generated phpunit command yourself, you might get the '
-        . 'answer.'
-      );
+      return array();
     }
 
     $coverage_dom = new DOMDocument();

src/unit/engine/PhpunitTestEngine.php

@@ -71,8 +71,10 @@ final class PhpunitTestEngine extends ArcanistBaseUnitTestEngine {
 
       $config = $this->configFile ? csprintf('-c %s', $this->configFile) : null;
 
-      $futures[$test_path] = new ExecFuture('%C %C --log-json %s %C %s',
-        $this->phpunitBinary, $config, $json_tmp, $clover, $test_path);
+      $stderr = "-d display_errors=stderr";
+
+      $futures[$test_path] = new ExecFuture('%C %C %C --log-json %s %C %s',
+        $this->phpunitBinary, $config, $stderr, $json_tmp, $clover, $test_path);
       $tmpfiles[$test_path] = array(
         'json' => $json_tmp,
         'clover' => $clover_tmp,
@@ -89,7 +91,8 @@ final class PhpunitTestEngine extends ArcanistBaseUnitTestEngine {
       $results[] = $this->parseTestResults(
         $test,
         $tmpfiles[$test]['json'],
-        $tmpfiles[$test]['clover']);
+        $tmpfiles[$test]['clover'],
+        $stderr);
     }
 
     return array_mergev($results);
@@ -101,16 +104,18 @@ final class PhpunitTestEngine extends ArcanistBaseUnitTestEngine {
    * @param string $path Path to test
    * @param string $json_tmp Path to phpunit json report
    * @param string $clover_tmp Path to phpunit clover report
+   * @param string $stderr Data written to stderr
    *
    * @return array
    */
-  private function parseTestResults($path, $json_tmp, $clover_tmp) {
+  private function parseTestResults($path, $json_tmp, $clover_tmp, $stderr) {
     $test_results = Filesystem::readFile($json_tmp);
     return id(new PhpunitResultParser())
       ->setEnableCoverage($this->getEnableCoverage())
       ->setProjectRoot($this->projectRoot)
       ->setCoverageFile($clover_tmp)
       ->setAffectedTests($this->affectedTests)
+      ->setStderr($stderr)
       ->parseTestResults($path, $test_results);
   }