Added link to docs for generic error about unique type instance (#149)

Author: vladar

src/Executor/Executor.php

@@ -945,7 +945,9 @@ private function completeValue(
                 $hint = "Make sure that type loader returns the same instance as defined in {$info->parentType}.{$info->fieldName}";
             }
             throw new InvariantViolation(
-                "Schema must contain unique named types but contains multiple types named \"$returnType\". $hint"
+                "Schema must contain unique named types but contains multiple types named \"$returnType\". ".
+                "$hint ".
+                "(see http://webonyx.github.io/graphql-php/type-system/#type-registry)."
             );
         }
 
@@ -1136,7 +1138,8 @@ private function ensureValidRuntimeType(
             throw new InvariantViolation(
                 "Schema must contain unique named types but contains multiple types named \"$runtimeType\". ".
                 "Make sure that `resolveType` function of abstract type \"{$returnType}\" returns the same ".
-                "type instance as referenced anywhere else within the schema."
+                "type instance as referenced anywhere else within the schema " .
+                "(see http://webonyx.github.io/graphql-php/type-system/#type-registry)."
             );
         }
 

src/Utils/TypeInfo.php

@@ -106,7 +106,8 @@ public static function extractTypes($type, array $typeMap = null)
         if (!empty($typeMap[$type->name])) {
             Utils::invariant(
                 $typeMap[$type->name] === $type,
-                "Schema must contain unique named types but contains multiple types named \"$type\"."
+                "Schema must contain unique named types but contains multiple types named \"$type\" ".
+                "(see http://webonyx.github.io/graphql-php/type-system/#type-registry)."
             );
             return $typeMap;
         }

tests/Executor/AbstractTest.php

@@ -483,7 +483,8 @@ public function testHintsOnConflictingTypeInstancesInResolveType()
         $this->assertEquals(
             'Schema must contain unique named types but contains multiple types named "Test". '.
             'Make sure that `resolveType` function of abstract type "Node" returns the same type instance '.
-            'as referenced anywhere else within the schema.',
+            'as referenced anywhere else within the schema '.
+            '(see http://webonyx.github.io/graphql-php/type-system/#type-registry).',
             $result->errors[0]->getMessage()
         );
     }

tests/Executor/ExecutorLazySchemaTest.php

@@ -185,7 +185,8 @@ public function testHintsOnConflictingTypeInstancesInDefinitions()
 
         $this->assertEquals(
             'Schema must contain unique named types but contains multiple types named "Test". '.
-            'Make sure that type loader returns the same instance as defined in Query.test',
+            'Make sure that type loader returns the same instance as defined in Query.test '.
+            '(see http://webonyx.github.io/graphql-php/type-system/#type-registry).',
             $result->errors[0]->getMessage()
         );
         $this->assertInstanceOf(

tests/Type/ValidationTest.php

@@ -359,7 +359,8 @@ public function testRejectsASchemaWhichRedefinesABuiltInType()
 
         $this->setExpectedException(
             InvariantViolation::class,
-            'Schema must contain unique named types but contains multiple types named "String".'
+            'Schema must contain unique named types but contains multiple types named "String" '.
+            '(see http://webonyx.github.io/graphql-php/type-system/#type-registry).'
         );
         new Schema(['query' => $QueryType]);
     }
@@ -389,7 +390,8 @@ public function testRejectsASchemaWhichDfinesAnObjectTypeTwice()
 
         $this->setExpectedException(
             InvariantViolation::class,
-            'Schema must contain unique named types but contains multiple types named "SameName".'
+            'Schema must contain unique named types but contains multiple types named "SameName" '.
+            '(see http://webonyx.github.io/graphql-php/type-system/#type-registry).'
         );
 
         new Schema([ 'query' => $QueryType ]);
@@ -427,7 +429,8 @@ public function testRejectsASchemaWhichHaveSameNamedObjectsImplementingAnInterfa
 
         $this->setExpectedException(
             InvariantViolation::class,
-            'Schema must contain unique named types but contains multiple types named "BadObject".'
+            'Schema must contain unique named types but contains multiple types named "BadObject" '.
+            '(see http://webonyx.github.io/graphql-php/type-system/#type-registry).'
         );
 
         new Schema([