Issue #3281193 by neclimdul: Improve GenerateThemeTest

   * @return \Symfony\Component\Process\Process

   *   The PHP process

   */

  private function generateThemeFromStarterkit() : Process {

  private function generateThemeFromStarterkit($env = NULL) : Process {

    $install_command = [

      $this->php,

      'core/scripts/drupal',

      '--name="Test custom starterkit theme"',

      '--description="Custom theme generated from a starterkit theme"',

    ];

    $process = new Process($install_command, NULL);

    $process = new Process($install_command, NULL, $env);

    $process->setTimeout(60);

    return $process;

  }

SH;

    file_put_contents($unavailableGitPath . '/git', $bash);

    chmod($unavailableGitPath . '/git', 0755);

    $oldPath = getenv('PATH');

    putenv('PATH=' . $unavailableGitPath . ':' . getenv('PATH'));

    // Confirm that 'git' is no longer available.

    $output = [];

    exec('git --help', $output, $status);

    $this->assertEquals(127, $status);

    $process = $this->generateThemeFromStarterkit();

    $env = [

      'PATH' => $unavailableGitPath . ':' . getenv('PATH'),

      'COLUMNS' => 80,

    ];

    $process = new Process([

      'git',

      '--help',

    ], NULL, $env);

    $process->run();

    $this->assertEquals(127, $process->getExitCode(), 'Fake git used by process.');

    $process = $this->generateThemeFromStarterkit($env);

    $result = $process->run();

    $this->assertEquals("[ERROR] The source theme starterkit_theme has a development version number     \n         (7.x-dev). Determining a specific commit is not possible because git is\n         not installed. Either install git or use a tagged release to generate a\n         theme.", trim($process->getOutput()), $process->getErrorOutput());

    $this->assertSame(1, $result);

    $this->assertFileDoesNotExist($this->getWorkspaceDirectory() . "/themes/test_custom_theme");

    putenv('PATH=' . $oldPath . ':' . getenv('PATH'));

  }

  /**