From 4227404aeee18f1d781e71ada32b2e15866c3685 Mon Sep 17 00:00:00 2001
From: Vladimir Razuvaev <vladimir.razuvaev@gmail.com>
Date: Tue, 7 Aug 2018 23:25:01 +0700
Subject: [PATCH] Added test for useful error when returning invalid value from
 resolveType

---
 src/Executor/Executor.php       | 11 ++++---
 tests/Executor/AbstractTest.php | 55 +++++++++++++++++++++++++++++++++
 2 files changed, 61 insertions(+), 5 deletions(-)

diff --git a/src/Executor/Executor.php b/src/Executor/Executor.php
index 26ecd09..4251554 100644
--- a/src/Executor/Executor.php
+++ b/src/Executor/Executor.php
@@ -1400,15 +1400,16 @@ class Executor
         if (! $runtimeType instanceof ObjectType) {
             throw new InvariantViolation(
                 sprintf(
-                    'Abstract type %1$s must resolve to an Object type at ' .
-                    'runtime for field %s.%s with value "%s", received "%s".' .
-                    'Either the %1$s type should provide a "resolveType" ' .
-                    'function or each possible types should provide an "isTypeOf" function.',
+                    'Abstract type %s must resolve to an Object type at ' .
+                    'runtime for field %s.%s with value "%s", received "%s". ' .
+                    'Either the %s type should provide a "resolveType" ' .
+                    'function or each possible type should provide an "isTypeOf" function.',
                     $returnType,
                     $info->parentType,
                     $info->fieldName,
                     Utils::printSafe($result),
-                    Utils::printSafe($runtimeType)
+                    Utils::printSafe($runtimeType),
+                    $returnType
                 )
             );
         }
diff --git a/tests/Executor/AbstractTest.php b/tests/Executor/AbstractTest.php
index 057b6a3..7236746 100644
--- a/tests/Executor/AbstractTest.php
+++ b/tests/Executor/AbstractTest.php
@@ -357,6 +357,61 @@ class AbstractTest extends TestCase
         $this->assertArraySubset($expected, $result);
     }
 
+    /**
+     * @it returning invalid value from resolveType yields useful error
+     */
+    public function testReturningInvalidValueFromResolveTypeYieldsUsefulError()
+    {
+        $fooInterface = new InterfaceType([
+            'name' => 'FooInterface',
+            'fields' => ['bar' => ['type' => Type::string()]],
+            'resolveType' => function () {
+                return [];
+            },
+        ]);
+
+        $fooObject = new ObjectType([
+            'name' => 'FooObject',
+            'fields' => ['bar' => ['type' => Type::string()]],
+            'interfaces' => [$fooInterface],
+        ]);
+
+        $schema = new Schema([
+            'query' => new ObjectType([
+                'name' => 'Query',
+                'fields' => [
+                    'foo' => [
+                        'type' => $fooInterface,
+                        'resolve' => function () {
+                            return 'dummy';
+                        },
+                    ],
+                ],
+            ]),
+            'types' => [$fooObject],
+        ]);
+
+        $result = GraphQL::executeQuery($schema, '{ foo { bar } }');
+
+        $expected = [
+            'data' => ['foo' => null],
+            'errors' => [
+                [
+                    'message' => 'Internal server error',
+                    'debugMessage' =>
+                        'Abstract type FooInterface must resolve to an Object type at ' .
+                        'runtime for field Query.foo with value "dummy", received "[]". ' .
+                        'Either the FooInterface type should provide a "resolveType" ' .
+                        'function or each possible type should provide an "isTypeOf" function.',
+                    'locations' => [['line' => 1, 'column' => 3]],
+                    'path' => ['foo'],
+                    'category' => 'internal',
+                ],
+            ],
+        ];
+        $this->assertEquals($expected, $result->toArray(true));
+    }
+
     /**
      * @it resolveType allows resolving with type name
      */