fix: find by timeout with detached screen (#1576)

* fix: improve error findBy* error message when screen is not beign attached.

* fix: detect detached screen and display proper error message.

* chore: improve error message

* chore: update link

* chore: update snapshots

Author: mdjastrzebski

src/queries/__tests__/find-by.test.tsx

@@ -0,0 +1,22 @@
+import * as React from 'react';
+import { View } from 'react-native';
+import { render, screen } from '../..';
+import { clearRenderResult } from '../../screen';
+
+test('findByTestId detects screen being detached', async () => {
+  render(<View />);
+
+  const promise = screen.findByTestId('not-exists', {}, { timeout: 50 });
+
+  // Detach screen
+  clearRenderResult();
+
+  await expect(promise).rejects.toThrowErrorMatchingInlineSnapshot(`
+    "Unable to find an element with testID: not-exists
+
+    Screen is no longer attached. Check your test for "findBy*" or "waitFor" calls that have not been awaited.
+
+    We recommend enabling "eslint-plugin-testing-library" to catch these issues at build time:
+    https://callstack.github.io/react-native-testing-library/docs/getting-started#eslint-plugin"
+  `);
+});

src/queries/make-queries.ts

@@ -87,6 +87,10 @@ function formatErrorMessage(message: string, printElementTree: boolean) {
     return message;
   }
 
+  if (screen.isDetached) {
+    return `${message}\n\nScreen is no longer attached. Check your test for "findBy*" or "waitFor" calls that have not been awaited.\n\nWe recommend enabling "eslint-plugin-testing-library" to catch these issues at build time:\nhttps://callstack.github.io/react-native-testing-library/docs/getting-started#eslint-plugin`;
+  }
+
   const json = screen.toJSON();
   if (!json) {
     return message;

src/screen.ts

@@ -12,7 +12,12 @@ const notImplementedDebug = () => {
 };
 notImplementedDebug.shallow = notImplemented;
 
-const defaultScreen: RenderResult = {
+interface Screen extends RenderResult {
+  isDetached?: boolean;
+}
+
+const defaultScreen: Screen = {
+  isDetached: true,
   get root(): ReactTestInstance {
     throw new Error(SCREEN_ERROR);
   },
@@ -112,10 +117,10 @@ const defaultScreen: RenderResult = {
   findAllByText: notImplemented,
 };
 
-export let screen: RenderResult = defaultScreen;
+export let screen: Screen = defaultScreen;
 
-export function setRenderResult(output: RenderResult) {
-  screen = output;
+export function setRenderResult(renderResult: RenderResult) {
+  screen = renderResult;
 }
 
 export function clearRenderResult() {