Add support for resolvers without fragments

Summary:
Remove validation for `rootFragment` on the resolver definition.

- With this we can expose plain functions as GraphQL fields
- With this we can extend object with client fields that may return Client or Server Objects.

Reviewed By: josephsavona

Differential Revision: D37119681

fbshipit-source-id: 203fd3e99d68096532b9eb3e45f661766da2402a

compiler/crates/relay-docblock/src/lib.rs

@@ -116,14 +116,6 @@ impl RelayResolverParser {
         }
         let live = self.fields.get(&LIVE_FIELD).copied();
         let root_fragment = self.get_field_with_value(*ROOT_FRAGMENT_FIELD)?;
-        if live.is_none() && root_fragment.is_none() {
-            self.errors.push(Diagnostic::error(
-                ErrorMessages::MissingField {
-                    field_name: *ROOT_FRAGMENT_FIELD,
-                },
-                ast.location,
-            ));
-        }
         let fragment_definition = root_fragment
             .map(|root_fragment| {
                 self.assert_fragment_definition(root_fragment.value, definitions_in_file)

compiler/crates/relay-docblock/tests/parse/fixtures/relay-resolver-missing-multiple-fields.invalid.expected

@@ -30,16 +30,6 @@ graphql`
 
 ✖︎ Missing docblock field "@fieldName"
 
-  /path/to/test/fixture/relay-resolver-missing-multiple-fields.invalid.js:10:3
-   10 │ *
-      │ ^
-   11 │  * @RelayResolver
-      │ ^^^^^^^^^^^^^^^^^
-   12 │  
-
-
-✖︎ Missing docblock field "@rootFragment"
-
   /path/to/test/fixture/relay-resolver-missing-multiple-fields.invalid.js:10:3
    10 │ *
       │ ^

packages/react-relay/__tests__/ClientOnlyQueries-test.js

@@ -25,6 +25,7 @@ const {
   Environment,
   Network,
   RecordSource,
+  RelayFeatureFlags,
   Store,
   commitLocalUpdate,
   createOperationDescriptor,
@@ -48,7 +49,17 @@ function createEnvironment(
   });
 }
 
-describe('Client Only Queries', () => {
+beforeEach(() => {
+  RelayFeatureFlags.ENABLE_RELAY_RESOLVERS = true;
+  RelayFeatureFlags.ENABLE_CLIENT_EDGES = true;
+});
+
+afterEach(() => {
+  RelayFeatureFlags.ENABLE_RELAY_RESOLVERS = false;
+  RelayFeatureFlags.ENABLE_CLIENT_EDGES = false;
+});
+
+describe('Client-only queries', () => {
   let renderer;
   let environment: IEnvironment;
 
@@ -217,3 +228,117 @@ describe('Client Only Queries', () => {
     );
   });
 });
+
+test('hello-world query', () => {
+  const environment = createEnvironment(RecordSource.create(), () => {
+    const error = new Error('Unexpected Network Error');
+    throw error;
+  });
+
+  function InnerTestComponent(props: {|fetchPolicy?: FetchPolicy|}) {
+    const data = useLazyLoadQuery(
+      graphql`
+        query ClientOnlyQueriesTest2Query {
+          hello(world: "World")
+        }
+      `,
+      {},
+      {
+        fetchPolicy: props.fetchPolicy ?? 'store-only',
+      },
+    );
+    return data.hello ?? 'MISSING';
+  }
+
+  function TestComponent({
+    environment: relayEnvironment,
+    ...rest
+  }: {|
+    environment: IEnvironment,
+    fetchPolicy?: FetchPolicy,
+  |}) {
+    return (
+      <RelayEnvironmentProvider environment={relayEnvironment}>
+        <React.Suspense fallback="Loading...">
+          <InnerTestComponent {...rest} />
+        </React.Suspense>
+      </RelayEnvironmentProvider>
+    );
+  }
+  let renderer;
+  TestRenderer.act(() => {
+    renderer = TestRenderer.create(
+      <TestComponent
+        environment={environment}
+        fetchPolicy="store-or-network"
+      />,
+    );
+  });
+
+  expect(renderer?.toJSON()).toBe('Hello, World!');
+});
+
+test('hello user query with client-edge query', () => {
+  const environment = createEnvironment(
+    RecordSource.create({
+      'client:root': {
+        __id: 'client:root',
+        __typename: '__Root',
+        'node(id:"4")': {__ref: '4'},
+      },
+      '4': {
+        id: '4',
+        __id: '4',
+        name: 'Alice',
+      },
+    }),
+    () => {
+      const error = new Error('Unexpected Network Error');
+      throw error;
+    },
+  );
+
+  function InnerTestComponent(props: {|fetchPolicy?: FetchPolicy|}) {
+    const data = useLazyLoadQuery(
+      graphql`
+        query ClientOnlyQueriesTest3Query {
+          hello_user(id: "4") @waterfall {
+            name
+          }
+        }
+      `,
+      {},
+      {
+        fetchPolicy: props.fetchPolicy ?? 'store-only',
+      },
+    );
+    return `Hello, ${data.hello_user?.name ?? 'MISSING'}!`;
+  }
+
+  function TestComponent({
+    environment: relayEnvironment,
+    ...rest
+  }: {|
+    environment: IEnvironment,
+    fetchPolicy?: FetchPolicy,
+  |}) {
+    return (
+      <RelayEnvironmentProvider environment={relayEnvironment}>
+        <React.Suspense fallback="Loading...">
+          <InnerTestComponent {...rest} />
+        </React.Suspense>
+      </RelayEnvironmentProvider>
+    );
+  }
+  let renderer;
+  TestRenderer.act(() => {
+    renderer = TestRenderer.create(
+      <TestComponent
+        environment={environment}
+        fetchPolicy="store-or-network"
+      />,
+    );
+  });
+
+  expect(renderer?.toJSON()).toBe('Hello, Alice!');
+});