fix: compact watchQueryOptions (#77)

Options with undefined values shouldn't be passed to Apollo Client, otherwise they'll override any default options set on the client. This compacting behavior to remove undefined values is copied from React Apollo.

src/__tests__/utils-test.ts

@@ -0,0 +1,8 @@
+import { compact } from '../utils';
+
+describe('compact', () => {
+  it('returns a new object omitting any keys with an undefined value', () => {
+    const compacted = compact({ a: 'value', b: 1, c: undefined });
+    expect(compacted.hasOwnProperty('c')).toBe(false);
+  });
+});

src/useQuery.ts

@@ -18,7 +18,7 @@ import {
   getCachedObservableQuery,
   invalidateCachedObservableQuery,
 } from './queryCache';
-import { Omit, objToKey } from './utils';
+import { Omit, compact, objToKey } from './utils';
 
 export interface QueryHookState<TData>
   extends Pick<
@@ -87,17 +87,18 @@ export function useQuery<TData = any, TVariables = OperationVariables>(
       : actualCachePolicy;
 
   const watchQueryOptions: WatchQueryOptions<TVariables> = useMemo(
-    () => ({
-      context,
-      errorPolicy,
-      fetchPolicy,
-      fetchResults,
-      metadata,
-      notifyOnNetworkStatusChange,
-      pollInterval,
-      query,
-      variables,
-    }),
+    () =>
+      compact({
+        context,
+        errorPolicy,
+        fetchPolicy,
+        fetchResults,
+        metadata,
+        notifyOnNetworkStatusChange,
+        pollInterval,
+        query,
+        variables,
+      }),
     [
       query,
 
@@ -112,7 +113,6 @@ export function useQuery<TData = any, TVariables = OperationVariables>(
       fetchResults,
     ]
   );
-
   const observableQuery = useMemo(
     () =>
       getCachedObservableQuery<TData, TVariables>(client, watchQueryOptions),

src/utils.ts

@@ -18,3 +18,16 @@ export function objToKey<T extends Record<string, any>>(obj: T): T | string {
 export function isPromiseLike<T>(value: unknown): value is PromiseLike<T> {
   return value != null && typeof (value as PromiseLike<T>).then === 'function';
 }
+
+export function compact(obj: any) {
+  return Object.keys(obj).reduce(
+    (acc, key) => {
+      if (obj[key] !== undefined) {
+        acc[key] = obj[key];
+      }
+
+      return acc;
+    },
+    {} as any
+  );
+}