Fix Hidden fields triggering error when using getSingleScalarResult()

Fixes #4257
HIDDEN fields was causing the "unicity" check to fail (NonUniqueResultException), because we was counting raw data instead of gathered row data.

lib/Doctrine/ORM/Internal/Hydration/SingleScalarHydrator.php

@@ -47,12 +47,12 @@ protected function hydrateAllData()
             throw new NonUniqueResultException('The query returned multiple rows. Change the query or use a different result function like getScalarResult().');
         }
 
-        if (count($data[key($data)]) > 1) {
+        $result = $this->gatherScalarRowData($data[key($data)]);
+
+        if (count($result) > 1) {
             throw new NonUniqueResultException('The query returned a row containing multiple columns. Change the query or use a different result function like getScalarResult().');
         }
 
-        $result = $this->gatherScalarRowData($data[key($data)]);
-
         return array_shift($result);
     }
 }

tests/Doctrine/Tests/ORM/Hydration/SingleScalarHydratorTest.php

@@ -90,4 +90,79 @@ public function testHydrateSingleScalar($name, $resultSet)
             $hydrator->hydrateAll($stmt, $rsm);
         }
     }
+
+
+
+
+    public static function singleScalarResultSetWithHiddenFieldProvider(): array
+    {
+        return [
+            // valid
+            [
+                'name'      => 'result1',
+                'resultSet' => [
+                    [
+                        'u__id'   => '1',
+                        'u__name' => 'romanb',
+                    ],
+                ],
+            ],
+            // valid
+            [
+                'name'      => 'result2',
+                'resultSet' => [
+                    [
+                        'u__name' => 'romanb',
+                    ],
+                ],
+            ],
+            // invalid
+            [
+                'name'      => 'result3',
+                'resultSet' => [
+                    [
+                        'u__id' => '1',
+                    ],
+                    [
+                        'u__id' => '2',
+                    ],
+                ],
+            ],
+        ];
+    }
+
+    /**
+     *
+     * @dataProvider singleScalarResultSetWithHiddenFieldProvider
+     */
+    public function testHydrateSingleScalarWithHiddenField($name, $resultSet)
+    {
+        $rsm = new ResultSetMapping;
+        $rsm->addScalarResult('u__id', 'id', 'string');
+
+        $stmt = new HydratorMockStatement($resultSet);
+        $hydrator = new SingleScalarHydrator($this->_em);
+
+        if ($name === 'result1') {
+            $result = $hydrator->hydrateAll($stmt, $rsm);
+            $this->assertEquals('1', $result);
+
+            return;
+        }
+
+        if ($name === 'result2') {
+            $result = $hydrator->hydrateAll($stmt, $rsm);
+            $this->assertEquals(null, $result);
+
+            return;
+        }
+
+        if ($name === 'result3') {
+            $this->expectException(NonUniqueResultException::class);
+            $hydrator->hydrateAll($stmt, $rsm);
+
+            return;
+        }
+    }
+
 }