at the end of the day, it was inevitable

behat/Common/Util/Matcher/Expander/OneExpander.php

@@ -0,0 +1,40 @@
+<?php
+
+namespace Common\Util\Matcher\Expander;
+
+use Coduo\ToString\StringConverter;
+
+/**
+ * Class OneExpander
+ * Check that only one array element matches specified expander.
+ *
+ * Example:
+ *  - array.one(field('property', value))
+ *  - array.one(entity('AppBundle:User'), field('id', 1))
+ *
+ * @package Common\Util\Matcher\Expander
+ */
+class OneExpander extends AbstractChainExpander
+{
+    /**
+     * @param mixed $value Value to match.
+     *
+     * @return boolean
+     */
+    public function match($value)
+    {
+        if (! is_array($value)) {
+            $this->error = 'One expander require "array", got '.
+                new StringConverter($value) .'.';
+            return false;
+        }
+
+        foreach ($value as $row) {
+            if (parent::match($row)) {
+                return true;
+            }
+        }
+
+        return false;
+    }
+}