Fixes #10. Don't count string interpolation as a scope beginning

src/Fixer/Whitespace/BlankLineBeforeReturnFixer.php

@@ -67,8 +67,12 @@ final class BlankLineBeforeReturnFixer extends AbstractFixer implements Whitespa
                             break;
                         }
 
+                        /** @var Token $backwardToken */
                         $backwardToken = $tokens[$backwardIndex];
-                        if ($backwardToken->getContent() === '{') {
+                        /** @var Token $nextToken */
+                        $nextToken = $tokens[$backwardIndex + 1];
+                        // Exclude string interpolation: "str {$var}"
+                        if ($backwardToken->getContent() === '{' && !$nextToken->isGivenKind(T_VARIABLE)) {
                             break;
                         }
 

tests/Fixer/Whitespace/BlankLineBeforeReturnFixerTest.php

@@ -180,6 +180,20 @@ return $c;',
     }
     ',
         ];
+        yield [
+            '<?php
+            if ($condition) {
+                $a = "Interpolation {$var}.";
+                return true;
+            }',
+        ];
+        yield [
+            '<?php
+            if ($condition) {
+                $a = "Deprecated interpolation ${var}.";
+                return true;
+            }',
+        ];
     }
 
     /**