apollo-server-testing throws error: Unable to create test client (TypeError: Cannot read property 'bind' of undefined)

[bigfish]

Using apollo-server & apollo-server-testing 2.22.2

Following documentation to setup an integration test here https://www.apollographql.com/docs/apollo-server/testing/testing/

I get the error when I run jest:

TypeError: Cannot read property 'bind' of undefined

     104 |         });
     105 |         // console.log(server);
   > 106 |         const { query } = createTestClient(server);
         |                           ^
     107 |
     108 |         const res = await query({
     109 |           query: GET_ROUTES

     at createTestClient (node_modules/apollo-server-testing/src/createTestClient.ts:31:52)
     at Object.<anonymous> (spec/routesResolver.spec.js:106:27)

Looking at the referenced source code, it is attempting to bind a function named executeOperation. Apparently this doesn't exist?

export default (server: ApolloServerBase): ApolloServerTestClient => {
  const executeOperation = server.executeOperation.bind(server);

Is there some mismatch between the testing library and the server?

[glasser]

This is a method that exists. I can't reproduce your issue; if you can post a complete reproduction (eg, a repo I can git clone or something on codesandbox.io) I can reopen and dig into it.

For what it's worth, apollo-server-testing is a VERY thin layer around executeOperation and I don't think having the separate package is really worth the added complexity of having to install another package, etc. I realize it is what we document but I'd suggest just using server.executeOperation directly (once you figure out why it doesn't exist for you?). We may remove apollo-server-testing in Apollo Server 3 (#4952). Here's an example of a PR that changes a project from using apollo-server-testing to using executeOperation: apollographql/federation#554

[bigfish]

ah, in the process of preparing the repo for the issue, I found my mistake.. I wasn't destructuring the returned value from my createTestClient() helper function, so I was passing an object like { server } to createTestClient(). After passing the server itself, it is working as expected. Perhaps a more helpful error message like 'The argument provided to createTestClient() is not a valid ApolloServer instance: ' could be thrown?

[glasser]

Maybe, but I think a better approach would just be to change the docs that mention apollo-server-testing to just document server.executeOperation instead and leave apollo-server-testing as a curio that exists only for backwards compatibility.