[BUGFIX] Clean up label generation in new content wizard

* Prevents generating the `fluxContent` tab unless needed.
* Uses same logic for generating all tabs and removes a redundant method
* Avoids generating a new tab if the name is in the reserved list `['common', 'menu', 'special', 'forms', 'plugins']`
* Allows localising the tab label via `flux.newContentWizard.$group` LLL reference
* First extension to register a tab decides the tab label
* Overriding the label of `fluxContent` and any other tab can be done in pageTSconfig

Close: FluidTYPO3#1472
Close: FluidTYPO3#1459

Classes/Helper/ContentTypeBuilder.php

@@ -27,6 +27,7 @@
 use TYPO3\CMS\Core\Utility\GeneralUtility;
 use TYPO3\CMS\Extbase\Object\ObjectManager;
 use TYPO3\CMS\Extbase\Utility\ExtensionUtility;
+use TYPO3\CMS\Extbase\Utility\LocalizationUtility;
 
 /**
  * Content Type Builder
@@ -171,7 +172,6 @@ public function registerContentType(
             }
         }
 
-        $this->initializeIfRequired();
         $this->registerExtbasePluginForForm($providerExtensionName, $pluginName, $form);
         $this->addPageTsConfig($form, $contentType);
 
@@ -237,10 +237,24 @@ public function addBoilerplateTableConfiguration($contentType)
      */
     protected function addPageTsConfig(Form $form, $contentType)
     {
+        if (TYPO3_MODE !== 'BE') {
+            return;
+        }
         // Icons required solely for use in the "new content element" wizard
         $formId = $form->getId();
-        $group = $form->getOption(Form::OPTION_GROUP) ?? 'fluxContent';
-        $this->initializeNewContentWizardGroup($this->sanitizeString($group), $group);
+        $group = $form->getOption(Form::OPTION_GROUP);
+        $groupName = $this->sanitizeString($group ?? 'fluxContent');
+        $extensionKey = ExtensionNamingUtility::getExtensionKey($form->getExtensionName());
+
+        $labelSubReference = 'flux.newContentWizard.' . $groupName;
+        $labelExtensionKey = $groupName === 'fluxContent' ? 'flux' : $extensionKey;
+        $labelReference = 'LLL:EXT:' . $labelExtensionKey . $form->getLocalLanguageFileRelativePath() . ':' . $labelSubReference;
+        $probedTranslation = LocalizationUtility::translate($labelReference);
+
+        $this->initializeNewContentWizardGroup(
+            $groupName,
+            $probedTranslation ? $labelReference : $groupName
+        );
 
         // Registration for "new content element" wizard to show our new CType (otherwise, only selectable via "Content type" drop-down)
         ExtensionManagementUtility::addPageTSConfig(
@@ -254,13 +268,13 @@ protected function addPageTsConfig(Form $form, $contentType)
                     }
                 }
                 mod.wizards.newContentElement.wizardItems.%s.show := addToList(%s)',
-                $this->sanitizeString($group),
+                $groupName,
                 $formId,
                 $this->addIcon($form, $contentType),
                 $form->getLabel(),
                 $form->getDescription(),
                 $contentType,
-                $group,
+                $groupName,
                 $formId
             )
         );
@@ -304,40 +318,25 @@ protected function initializeNewContentWizardGroup($groupName, $groupLabel)
         if (isset($groups[$groupName])) {
             return;
         }
+
+        if (in_array($groupName, ['common', 'menu', 'special', 'forms', 'plugins'])) {
+            return;
+        }
+
         ExtensionManagementUtility::addPageTSConfig(
             sprintf(
                 'mod.wizards.newContentElement.wizardItems.%s {
-                    header = %s
-                    show = *
+                    %s
                     elements {
                     }
                 }',
                 $groupName,
-                $groupLabel
+                $groupLabel ? 'header = ' . $groupLabel : ''
             )
         );
         $groups[$groupName] = true;
     }
 
-    /**
-     * @return void
-     */
-    protected function initializeIfRequired()
-    {
-        static $initialized = false;
-
-        if (!$initialized) {
-            // Register the stub/group/tab which will store all elements added this way. We wrap this in our Core
-            // registration class to avoid this tab being added unless elements are used. Then toggle the static
-            // initialized flag to avoid repeating this insertion.
-            $this->initializeNewContentWizardGroup(
-                'fluxContent',
-                'LLL:EXT:flux/Resources/Private/Language/locallang.xlf:newContentWizard.fluxContent'
-            );
-            $initialized = true;
-        }
-    }
-
     /**
      * @return FrontendInterface
      */

Resources/Private/Language/locallang.xlf

@@ -3,7 +3,7 @@
 	<file source-language="en" datatype="plaintext" original="messages" product-name="flux" date="2014-01-05T14:38:32+01:00">
 		<header/>
 		<body>
-			<trans-unit id="newContentWizard.fluxContent">
+			<trans-unit id="flux.newContentWizard.fluxContent">
 				<source>Flux content</source>
 			</trans-unit>
 			<trans-unit id="tt_content.tx_flux_container">

Tests/Unit/Helper/ContentTypeBuilderTest.php

@@ -12,6 +12,7 @@
 use FluidTYPO3\Flux\Helper\ContentTypeBuilder;
 use FluidTYPO3\Flux\Provider\Provider;
 use FluidTYPO3\Flux\Tests\Unit\AbstractTestCase;
+use TYPO3\CMS\Lang\LanguageService;
 
 /**
  * ContentTypeBuilderTest
@@ -57,6 +58,7 @@ public function testRegisterContentType()
         $provider->expects($this->once())->method('getForm')->willReturn($form);
 
         $GLOBALS['TCA']['tt_content']['columns']['list_type']['config']['items'] = [];
+        $GLOBALS['LANG'] = $this->getMockBuilder(LanguageService::class)->disableOriginalConstructor()->getMock();
 
         $subject->registerContentType(
             'FluidTYPO3.Flux',