[BUGFIX] Ignore f:then/f:else outside condition context

src/Core/ViewHelper/AbstractConditionViewHelper.php

@@ -118,7 +118,7 @@ protected function renderThenChild()
         foreach ($this->viewHelperNode->getChildNodes() as $childNode) {
             if ($childNode instanceof ViewHelperNode
                 && str_ends_with($childNode->getViewHelperClassName(), 'ThenViewHelper')) {
-                $data = $childNode->evaluate($this->renderingContext);
+                $data = $childNode->evaluateChildNodes($this->renderingContext);
                 return $data;
             }
             if ($childNode instanceof ViewHelperNode
@@ -184,7 +184,7 @@ protected function renderElseChild()
                 $arguments = $childNode->getArguments();
                 if (isset($arguments['if'])) {
                     if ($arguments['if']->evaluate($this->renderingContext)) {
-                        return $childNode->evaluate($this->renderingContext);
+                        return $childNode->evaluateChildNodes($this->renderingContext);
                     }
                 } elseif ($elseNode === null) {
                     $elseNode = $childNode;
@@ -205,7 +205,7 @@ protected function renderElseChild()
 
         // If a f:else node exists, evaluate its content
         if ($elseNode instanceof ViewHelperNode) {
-            return $elseNode->evaluate($this->renderingContext);
+            return $elseNode->evaluateChildNodes($this->renderingContext);
         }
 
         // If only the condition is specified, but no then/else handling, the whole ViewHelper should

src/ViewHelpers/ElseViewHelper.php

@@ -50,12 +50,14 @@ public function initializeArguments()
     }
 
     /**
-     * @return string the rendered string
+     * Does nothing unless used in context of condition ViewHelper, such as f:if
+     *
      * @api
+     * @todo consider throwing an exception here in future versions
      */
-    public function render()
+    public function render(): string
     {
-        return $this->renderChildren();
+        return '';
     }
 
     /**
@@ -64,9 +66,9 @@ public function render()
      * @param string $initializationPhpCode
      * @param ViewHelperNode $node
      * @param TemplateCompiler $compiler
-     * @return string|null
+     * @return string
      */
-    public function compile($argumentsName, $closureName, &$initializationPhpCode, ViewHelperNode $node, TemplateCompiler $compiler)
+    public function compile($argumentsName, $closureName, &$initializationPhpCode, ViewHelperNode $node, TemplateCompiler $compiler): string
     {
         return '\'\'';
     }

src/ViewHelpers/ThenViewHelper.php

@@ -25,14 +25,14 @@ class ThenViewHelper extends AbstractViewHelper
     protected $escapeOutput = false;
 
     /**
-     * Just render everything.
+     * Does nothing unless used in context of condition ViewHelper, such as f:if
      *
-     * @return string the rendered string
      * @api
+     * @todo consider throwing an exception here in future versions
      */
-    public function render()
+    public function render(): string
     {
-        return $this->renderChildren();
+        return '';
     }
 
     /**
@@ -43,7 +43,7 @@ public function render()
      * @param TemplateCompiler $compiler
      * @return string
      */
-    public function compile($argumentsName, $closureName, &$initializationPhpCode, ViewHelperNode $node, TemplateCompiler $compiler)
+    public function compile($argumentsName, $closureName, &$initializationPhpCode, ViewHelperNode $node, TemplateCompiler $compiler): string
     {
         return '\'\'';
     }

tests/Functional/ViewHelpers/IfThenElseViewHelperTest.php

@@ -566,6 +566,27 @@ public static function renderDataProvider(): \Generator
             true,
         ];
 
+        yield 'f:then without f:if context' => [
+            '<f:then>foo</f:then>',
+            [],
+            '',
+        ];
+        yield 'f:else without f:if context' => [
+            '<f:else>foo</f:else>',
+            [],
+            '',
+        ];
+        yield 'f:else-if without f:if context, verdict true' => [
+            '<f:else if="{verdict}">foo</f:else>',
+            ['verdict' => true],
+            '',
+        ];
+        yield 'f:else-if without f:if context, verdict false' => [
+            '<f:else if="{verdict}">foo</f:else>',
+            ['verdict' => false],
+            '',
+        ];
+
         /*
          * @todo This should work but doesn't at the moment. This is probably related to the boolean
          *       parser not converting variable nodes correctly. There is a related todo in the BooleanParserTest.