chore(apollo-server-testing): improve types

CHANGELOG.md

@@ -13,6 +13,7 @@ The version headers in this history reflect the versions of Apollo Server itself
 
 ## v2.19.0
 
+- `apollo-server-testing`: types: Allow generic `variables` usage of `query` and `mutate` functions. [PR #4383](https://github.com/apollograpqh/apollo-server/pull/4383)
 - `apollo-server-core`: Explicitly include `lru-cache` dependency in `apollo-server-core`'s dependencies. [PR #4600](https://github.com/apollographql/apollo-server/pull/4600)
 - `apollo-server-core`: Update dependency for `@apollographql/graphql-playground-react` to `v1.7.34` to incorporate [`33c48183`](https://github.com/apollographql/graphql-playground/commit/33c48183229e59f0d21f7f4fdd57bed5a973a5cf) which, as an upstream change, should improve support for `graphql@15` features, like interfaces implementing interfaces.
 - `apollo-server-express`: Export the `GetMiddlewareOptions` type. [PR #4599](https://github.com/apollograpqh/apollo-server/pull/4599)

packages/apollo-server-testing/src/__tests__/createTestClient.test.ts

@@ -53,6 +53,17 @@ describe('createTestClient', () => {
     expect(res.data).toEqual({ test: 'wow' });
   });
 
+  it('works with generic types', async () => {
+    const query = `query test($echo: String){ test(echo: $echo) }`;
+    type Data = { test?: string | null; };
+    type Variables = { echo: string; };
+    const client = createTestClient(myTestServer);
+    const res1 = await client.query<Data>({ query, variables: { echo: 'onlydata' } });
+    expect(res1.data).toEqual({ test: 'onlydata' });
+    const res2 = await client.query<Data, Variables>({ query, variables: { echo: 'data and variables' } });
+    expect(res2.data).toEqual({ test: 'data and variables' });
+  })
+
   it('resolves with context', async () => {
     const query = `{ hello }`;
     const client = createTestClient(myTestServer);

packages/apollo-server-testing/src/createTestClient.ts

@@ -1,30 +1,30 @@
 import { ApolloServerBase } from 'apollo-server-core';
-import { GraphQLResponse } from 'apollo-server-types';
+import { GraphQLResponse as GraphQLResponseType } from 'apollo-server-types';
 import { print, DocumentNode } from 'graphql';
 
 type StringOrAst = string | DocumentNode;
 
 // A query must not come with a mutation (and vice versa).
-type Query = {
+type Query<TVariables = Record<string, any>> = {
   query: StringOrAst;
   mutation?: undefined;
-  variables?: {
-    [name: string]: any;
-  };
+  variables?: TVariables;
   operationName?: string;
 };
-type Mutation = {
+type Mutation<TVariables = Record<string, any>> = {
   mutation: StringOrAst;
   query?: undefined;
-  variables?: {
-    [name: string]: any;
-  };
+  variables?: TVariables;
   operationName?: string;
 };
 
+type GraphQLResponse<TData> = Omit<GraphQLResponseType, 'data'> & {
+  data?: TData;
+};
+
 export interface ApolloServerTestClient {
-  query: (query: Query) => Promise<GraphQLResponse>;
-  mutate: (mutation: Mutation) => Promise<GraphQLResponse>;
+  query<TData = any, TVariables = Record<string, any>>(query: Query<TVariables>): Promise<GraphQLResponse<TData>>;
+  mutate<TData = any, TVariables = Record<string, any>>(mutation: Mutation<TVariables>): Promise<GraphQLResponse<TData>>;
 }
 
 export default (server: ApolloServerBase): ApolloServerTestClient => {
@@ -46,5 +46,5 @@ export default (server: ApolloServerBase): ApolloServerTestClient => {
     });
   };
 
-  return { query: test, mutate: test };
+  return { query: test, mutate: test } as ApolloServerTestClient;
 };