feat(no-node-access): add allowContainerFirstChild option (#611)

docs/rules/no-node-access.md

@@ -51,6 +51,25 @@ within(signinModal).getByPlaceholderText('Username');
 document.getElementById('submit-btn').closest('button');
 ```
 
+## Options
+
+This rule has one option:
+
+- `allowContainerFirstChild`: **disabled by default**. When we have container
+  with rendered content then the easiest way to access content itself is [by using
+  `firstChild` property](https://testing-library.com/docs/react-testing-library/api/#container-1). Use this option in cases when this is hardly avoidable.
+
+  ```js
+  "testing-library/no-node-access": ["error", {"allowContainerFirstChild": true}]
+  ```
+
+Correct:
+
+```jsx
+const { container } = render(<MyComponent />);
+expect(container.firstChild).toMatchSnapshot();
+```
+
 ## Further Reading
 
 ### Properties / methods that return another Node

lib/rules/no-node-access.ts

@@ -5,7 +5,7 @@ import { ALL_RETURNING_NODES } from '../utils';
 
 export const RULE_NAME = 'no-node-access';
 export type MessageIds = 'noNodeAccess';
-type Options = [];
+export type Options = [{ allowContainerFirstChild: boolean }];
 
 export default createTestingLibraryRule<Options, MessageIds>({
   name: RULE_NAME,
@@ -25,11 +25,24 @@ export default createTestingLibraryRule<Options, MessageIds>({
       noNodeAccess:
         'Avoid direct Node access. Prefer using the methods from Testing Library.',
     },
-    schema: [],
+    schema: [
+      {
+        type: 'object',
+        properties: {
+          allowContainerFirstChild: {
+            type: 'boolean',
+          },
+        },
+      },
+    ],
   },
-  defaultOptions: [],
+  defaultOptions: [
+    {
+      allowContainerFirstChild: false,
+    },
+  ],
 
-  create(context, _, helpers) {
+  create(context, [{ allowContainerFirstChild = false }], helpers) {
     function showErrorForNodeAccess(node: TSESTree.MemberExpression) {
       // This rule is so aggressive that can cause tons of false positives outside test files when Aggressive Reporting
       // is enabled. Because of that, this rule will skip this mechanism and report only if some Testing Library package
@@ -42,6 +55,10 @@ export default createTestingLibraryRule<Options, MessageIds>({
         ASTUtils.isIdentifier(node.property) &&
         ALL_RETURNING_NODES.includes(node.property.name)
       ) {
+        if (allowContainerFirstChild && node.property.name === 'firstChild') {
+          return;
+        }
+
         context.report({
           node,
           loc: node.property.loc.start,

tests/lib/rules/no-node-access.test.ts

@@ -1,8 +1,12 @@
-import rule, { RULE_NAME } from '../../../lib/rules/no-node-access';
+import type { TSESLint } from '@typescript-eslint/utils';
+
+import rule, { RULE_NAME, Options } from '../../../lib/rules/no-node-access';
 import { createRuleTester } from '../test-utils';
 
 const ruleTester = createRuleTester();
 
+type ValidTestCase = TSESLint.ValidTestCase<Options>;
+
 const SUPPORTED_TESTING_FRAMEWORKS = [
   '@testing-library/angular',
   '@testing-library/react',
@@ -11,51 +15,52 @@ const SUPPORTED_TESTING_FRAMEWORKS = [
 ];
 
 ruleTester.run(RULE_NAME, rule, {
-  valid: SUPPORTED_TESTING_FRAMEWORKS.flatMap((testingFramework) => [
-    {
-      code: `
+  valid: SUPPORTED_TESTING_FRAMEWORKS.flatMap<ValidTestCase>(
+    (testingFramework) => [
+      {
+        code: `
         import { screen } from '${testingFramework}';
 
         const buttonText = screen.getByText('submit');
       `,
-    },
-    {
-      code: `
+      },
+      {
+        code: `
         import { screen } from '${testingFramework}';
 
         const { getByText } = screen
         const firstChild = getByText('submit');
         expect(firstChild).toBeInTheDocument()
       `,
-    },
-    {
-      code: `
+      },
+      {
+        code: `
         import { screen } from '${testingFramework}';
 
         const firstChild = screen.getByText('submit');
         expect(firstChild).toBeInTheDocument()
       `,
-    },
-    {
-      code: `
+      },
+      {
+        code: `
         import { screen } from '${testingFramework}';
 
         const { getByText } = screen;
         const button = getByRole('button');
         expect(button).toHaveTextContent('submit');
       `,
-    },
-    {
-      code: `
+      },
+      {
+        code: `
         import { render, within } from '${testingFramework}';
 
         const { getByLabelText } = render(<MyComponent />);
         const signInModal = getByLabelText('Sign In');
         within(signInModal).getByPlaceholderText('Username');
       `,
-    },
-    {
-      code: `
+      },
+      {
+        code: `
       // case: code not related to testing library at all
       ReactDOM.render(
         <CommProvider useDsa={false}>
@@ -70,25 +75,36 @@ ruleTester.run(RULE_NAME, rule, {
         document.getElementById('root')
       );
       `,
-    },
-    {
-      settings: {
-        'testing-library/utils-module': 'test-utils',
       },
-      code: `
+      {
+        settings: {
+          'testing-library/utils-module': 'test-utils',
+        },
+        code: `
       // case: custom module set but not imported (aggressive reporting limited)
       const closestButton = document.getElementById('submit-btn').closest('button');
       expect(closestButton).toBeInTheDocument();
       `,
-    },
-    {
-      code: `
+      },
+      {
+        code: `
       // case: without importing TL (aggressive reporting skipped)
       const closestButton = document.getElementById('submit-btn')
       expect(closestButton).toBeInTheDocument();
       `,
-    },
-  ]),
+      },
+      {
+        options: [{ allowContainerFirstChild: true }],
+        code: `
+        import { render } from '${testingFramework}';
+
+        const { container } = render(<MyComponent />)
+
+        expect(container.firstChild).toMatchSnapshot()
+      `,
+      },
+    ]
+  ),
   invalid: SUPPORTED_TESTING_FRAMEWORKS.flatMap((testingFramework) => [
     {
       settings: {
@@ -291,5 +307,22 @@ ruleTester.run(RULE_NAME, rule, {
         },
       ],
     },
+    {
+      code: `
+        import { render } from '${testingFramework}';
+
+        const { container } = render(<MyComponent />)
+
+        expect(container.firstChild).toMatchSnapshot()
+      `,
+      errors: [
+        {
+          // error points to `firstChild`
+          line: 6,
+          column: 26,
+          messageId: 'noNodeAccess',
+        },
+      ],
+    },
   ]),
 });