@prints can match a single char

src/Subscriber/TestExecutor.php

@@ -100,7 +100,7 @@ private static function expectedOutput(string $code): string
         $expectedOutput = [];
 
         foreach (\explode(PHP_EOL, $code) as $line) {
-            \preg_match("/\/\/\s*@prints\s*(?<text>[^\s].*[^\s])\s*$/", $line, $matches);
+            \preg_match("/\/\/\s*@prints\s*(?<text>[^\s].*)$/", $line, $matches);
 
             if (\array_key_exists("text", $matches)) {
                 $expectedOutput[] = $matches["text"];

tests/data/examples/output/single-char.php

@@ -0,0 +1,3 @@
+<?php
+
+echo 'a'; // @prints a

tests/data/examples/output/trailing-spaces-are-ignored.php

@@ -0,0 +1,3 @@
+<?php
+
+echo 'a '; // @prints a