Issue #3259888 by Spokje, daffie: InstallUninstallTest fails on enabling both...

    // - That enabling more than one module at the same time does not lead to

    //   any errors.

    $edit = [];

    $experimental = FALSE;

    $count_experimental = 0;

    $count_deprecated = 0;

    foreach ($all_modules as $name => $module) {

      $edit['modules[' . $name . '][enable]'] = TRUE;

      // Track whether there is at least one experimental module.

      if ($module->info[ExtensionLifecycle::LIFECYCLE_IDENTIFIER] === ExtensionLifecycle::EXPERIMENTAL) {

        $experimental = TRUE;

        $count_experimental++;

      }

      if ($module->info[ExtensionLifecycle::LIFECYCLE_IDENTIFIER] === ExtensionLifecycle::DEPRECATED) {

        $count_deprecated++;

      }

    }

    $this->drupalGet('admin/modules');

    $this->submitForm($edit, 'Install');

    // If there are experimental modules, click the confirm form.

    if ($experimental) {

      $this->assertSession()->pageTextContains('Are you sure you wish to enable experimental modules?');

    // If there are experimental and deprecated modules, click the confirm form.

    if ($count_experimental > 0 && $count_deprecated > 0) {

      $this->assertSession()->titleEquals('Are you sure you wish to enable experimental and deprecated modules? | Drupal');

      $this->submitForm([], 'Continue');

    }

    // If there are experimental, and no deprecated modules, click the confirm

    // form.

    elseif ($count_experimental > 0) {

      if ($count_experimental === 1) {

        $page_title = 'Are you sure you wish to enable an experimental module? | Drupal';

      }

      else {

        $page_title = 'Are you sure you wish to enable experimental modules? | Drupal';

      }

      $this->assertSession()->titleEquals($page_title);

      $this->submitForm([], 'Continue');

    }

    // If there are deprecated, and no experimental modules, click the confirm

    // form.

    elseif ($count_deprecated > 0) {

      if ($count_deprecated === 1) {

        $page_title = 'Are you sure you wish to enable a deprecated module? | Drupal';

      }

      else {

        $page_title = 'Are you sure you wish to enable deprecated modules? | Drupal';

      }

      $this->assertSession()->titleEquals($page_title);

      $this->submitForm([], 'Continue');

    }

    $this->assertSession()->pageTextContains(count($all_modules) . ' modules have been enabled: ');