`register_graphql_interfaces_to_types` is not working

[jasonbahl]

Problem

The register_graphql_interfaces_to_types() function isn't working as expected.

The tests (https://github.com/wp-graphql/wp-graphql/blob/develop/tests/wpunit/RegisterInterfaceToTypeTest.php) for this functionality pass, but the functionality doesn't seem to work in practice.

Steps to reproduce

1. Take the code from the test and drop in in an active PHP file (like a plugin file or theme's functions.php):

add_action( 'graphql_register_types', function() {

    register_graphql_object_type( 'TestType', [
        'fields' => [
            'a' => [
                'type' => 'String'
            ]
        ]
    ]);

    register_graphql_interface_type( 'TestInterface', [
        'fields' => [
            'b' => [
                'type' => 'String',
            ],
        ],
    ]);

    register_graphql_interfaces_to_types( [ 'TestInterface' ], [ 'TestType' ] );

} );

2. Open GraphiQL and execute the same query that's executed in the test:

query GetType {
  __type(name: "TestType") {
    name
    kind
    interfaces {
      name
    }
    fields {
      name
    }
  }
}

3. See that the Interfaces are not returned:

{
  "data": {
    "__type": {
      "name": "TestType",
      "kind": "OBJECT",
      "interfaces": [],
      "fields": [
        {
          "name": "a"
        }
      ]
    }
  }
}

Expected Behavior

I expect the GraphQL Query for the Type to return the interfaces that are applied by the Type, and I expect the field enforced by the Interface to also be returned in the fields list.

{
  "data": {
    "__type": {
      "name": "TestType",
      "kind": "OBJECT",
      "interfaces": [
        {
          "name": "TestInterface" <-- this is expected, but missing
        }
      ],
      "fields": [
        {
          "name": "a"
        },
        {
          "name": "b" # <-- this is expected, but missing
        }
      ]
    }
  }

[jasonbahl]

Updates:

• I reverted to v1.4.0 and this functionality works.
• It does not work in v1.5.3 🤔
• It does not work in v1.4.3 🤔
• It does not work in v1.4.1 🤔
• double checked, it does indeed work in v1.4.0, so it seems that v1.4.1 is the culprit.

[jasonbahl]

Aha!

This is only an issue when I'm also running my beta "WPGraphQL Block Editor" extension 🤔

Will dig into that 👀

I have a feeling it has to do with multiple plugins registering interfaces to types? 🤔

[jasonbahl]

Ok, closing this as I've determined it's not a bug with WPGraphQL but was a bug with my local setup. 🤦🏻‍♂️

I had a plugin that I was working on that had WPGraphQL as a composer dependency and so I was loading WPGraphQL twice which was causing some real funky behavior 🤦🏻‍♂️