From e019b4dd7968f23ba500235e866e74f05fbed9de Mon Sep 17 00:00:00 2001
From: Sarah Dayan <sarah.dayan@algolia.com>
Date: Wed, 16 Jun 2021 10:46:32 +0200
Subject: [PATCH] fix(core): trigger invariant when user doesn't return
 anything from `getItems` (#607)

* fix: trigger invariant when user doesn't return anything from getItems

* tests: test invariant when not returning from getItems

* fix: remove pre-resolve invariant

* feat: check that every item is truthy in post-resolve invariant

* fix: rmeove unused dependency

* feat: add sourceId in error message

* feat: use second invariant for undefined items

* feat: add link to docs in invariant
---
 .../src/__tests__/getSources.test.ts          | 22 ++++++++++++++++++
 packages/autocomplete-core/src/resolve.ts     | 23 ++++++++++++++++---
 2 files changed, 42 insertions(+), 3 deletions(-)

diff --git a/packages/autocomplete-core/src/__tests__/getSources.test.ts b/packages/autocomplete-core/src/__tests__/getSources.test.ts
index 686bc03d0..9cbd5b795 100644
--- a/packages/autocomplete-core/src/__tests__/getSources.test.ts
+++ b/packages/autocomplete-core/src/__tests__/getSources.test.ts
@@ -6,6 +6,7 @@ import {
   runAllMicroTasks,
 } from '../../../../test/utils';
 import { createAutocomplete } from '../createAutocomplete';
+import * as handlers from '../onInput';
 
 describe('getSources', () => {
   test('gets calls on input', () => {
@@ -110,4 +111,25 @@ describe('getSources', () => {
 
     expect(onStateChange.mock.calls.pop()[0].state.collections).toHaveLength(2);
   });
+
+  test('with nothing returned from getItems throws', async () => {
+    const spy = jest.spyOn(handlers, 'onInput');
+
+    const { inputElement } = createPlayground(createAutocomplete, {
+      getSources() {
+        return [createSource({ sourceId: 'source1', getItems: () => {} })];
+      },
+    });
+
+    await expect(() => {
+      inputElement.focus();
+      userEvent.type(inputElement, 'a');
+
+      return spy.mock.results[0].value;
+    }).rejects.toThrow(
+      '[Autocomplete] The `getItems` function from source "source1" must return an array of items but returned undefined.\n\nDid you forget to return items?\n\nSee: https://www.algolia.com/doc/ui-libraries/autocomplete/core-concepts/sources/#param-getitems'
+    );
+
+    spy.mockRestore();
+  });
 });
diff --git a/packages/autocomplete-core/src/resolve.ts b/packages/autocomplete-core/src/resolve.ts
index 1505f77cd..9e83ed186 100644
--- a/packages/autocomplete-core/src/resolve.ts
+++ b/packages/autocomplete-core/src/resolve.ts
@@ -27,7 +27,7 @@ function isDescription<TItem extends BaseItem>(
 function isRequesterDescription<TItem extends BaseItem>(
   description: TItem[] | TItem[][] | RequesterDescription<TItem>
 ): description is RequesterDescription<TItem> {
-  return Boolean((description as RequesterDescription<TItem>).execute);
+  return Boolean((description as RequesterDescription<TItem>)?.execute);
 }
 
 type PackedDescription<TItem extends BaseItem> = {
@@ -172,9 +172,26 @@ export function postResolve<TItem extends BaseItem>(
 
     invariant(
       Array.isArray(items),
-      `The \`getItems\` function must return an array of items but returned type ${JSON.stringify(
+      `The \`getItems\` function from source "${
+        source.sourceId
+      }" must return an array of items but returned type ${JSON.stringify(
         typeof items
-      )}:\n\n${JSON.stringify(items, null, 2)}`
+      )}:\n\n${JSON.stringify(items, null, 2)}.
+
+See: https://www.algolia.com/doc/ui-libraries/autocomplete/core-concepts/sources/#param-getitems`
+    );
+
+    invariant(
+      (items as Array<typeof items>).every(Boolean),
+      `The \`getItems\` function from source "${
+        source.sourceId
+      }" must return an array of items but returned ${JSON.stringify(
+        undefined
+      )}.
+
+Did you forget to return items?
+
+See: https://www.algolia.com/doc/ui-libraries/autocomplete/core-concepts/sources/#param-getitems`
     );
 
     return {