Merge pull request #39 from primer/slots-rule

.changeset/soft-rabbits-stare.md

@@ -0,0 +1,5 @@
+---
+"eslint-plugin-primer-react": major
+---
+
+Add `direct-slot-children` rule

README.md

@@ -29,5 +29,6 @@ ESLint rules for Primer React
 
 ## Rules
 
+- [direct-slot-children](https://github.com/primer/eslint-plugin-primer-react/blob/main/docs/rules/direct-slot-children.md)
 - [no-deprecated-colors](https://github.com/primer/eslint-plugin-primer-react/blob/main/docs/rules/no-deprecated-colors.md)
 - [no-system-props](https://github.com/primer/eslint-plugin-primer-react/blob/main/docs/rules/no-system-props.md)

docs/rules/direct-slot-children.md

@@ -0,0 +1,39 @@
+# Enforce direct parent-child relationship of slot components (direct-slot-children)
+
+Some Primer React components use a slots pattern under the hood to render subcomponents in specific places. For example, the `PageLayout` component renders `PageLayout.Header` in the header area, and `PageLayout.Footer` in the footer area. These subcomponents must be direct children of the parent component, and cannot be nested inside other components.
+
+## Rule details
+
+This rule enforces that slot components are direct children of their parent component.
+
+👎 Examples of **incorrect** code for this rule:
+
+```jsx
+/* eslint primer-react/direct-slot-children: "error" */
+import {PageLayout} from '@primer/react'
+
+const MyHeader = () => <PageLayout.Header>Header</PageLayout.Header>
+
+const App = () => (
+  <PageLayout>
+    <MyHeader />
+  </PageLayout>
+)
+```
+
+👍 Examples of **correct** code for this rule:
+
+```jsx
+/* eslint primer-react/direct-slot-children: "error" */
+import {PageLayout} from '@primer/react'
+
+const MyHeader = () => <div>Header</div>
+
+const App = () => (
+  <PageLayout>
+    <PageLayout.Header>
+      <MyHeader />
+    </PageLayout.Header>
+  </PageLayout>
+)
+```

package.json

@@ -29,8 +29,8 @@
     "jest": "^27.0.6"
   },
   "peerDependencies": {
-    "eslint": "^8.0.1",
-    "@primer/primitives": ">=4.6.2"
+    "@primer/primitives": ">=4.6.2",
+    "eslint": "^8.0.1"
   },
   "prettier": "@github/prettier-config",
   "dependencies": {

src/rules/__tests__/direct-slot-children.test.js

@@ -0,0 +1,67 @@
+const rule = require('../direct-slot-children')
+const {RuleTester} = require('eslint')
+
+const ruleTester = new RuleTester({
+  parserOptions: {
+    ecmaVersion: 'latest',
+    sourceType: 'module',
+    ecmaFeatures: {
+      jsx: true
+    }
+  }
+})
+
+ruleTester.run('direct-slot-children', rule, {
+  valid: [
+    `import {PageLayout} from '@primer/react'; <PageLayout><PageLayout.Header>Header</PageLayout.Header><PageLayout.Footer>Footer</PageLayout.Footer></PageLayout>`,
+    `import {PageLayout} from '@primer/react'; <PageLayout><div><PageLayout.Pane>Header</PageLayout.Pane></div></PageLayout>`,
+    `import {PageLayout} from 'some-library'; <PageLayout.Header>Header</PageLayout.Header>`
+  ],
+  invalid: [
+    {
+      code: `import {PageLayout} from '@primer/react'; <PageLayout.Header>Header</PageLayout.Header>`,
+      errors: [
+        {
+          messageId: 'directSlotChildren',
+          data: {childName: 'PageLayout.Header', parentName: 'PageLayout'}
+        }
+      ]
+    },
+    {
+      code: `import {PageLayout} from '@primer/react/drafts'; <PageLayout.Header>Header</PageLayout.Header>`,
+      errors: [
+        {
+          messageId: 'directSlotChildren',
+          data: {childName: 'PageLayout.Header', parentName: 'PageLayout'}
+        }
+      ]
+    },
+    {
+      code: `import {PageLayout} from '@primer/react'; <div><PageLayout.Header>Header</PageLayout.Header></div>`,
+      errors: [
+        {
+          messageId: 'directSlotChildren',
+          data: {childName: 'PageLayout.Header', parentName: 'PageLayout'}
+        }
+      ]
+    },
+    {
+      code: `import {PageLayout} from '@primer/react'; <PageLayout><div><PageLayout.Header>Header</PageLayout.Header></div></PageLayout>`,
+      errors: [
+        {
+          messageId: 'directSlotChildren',
+          data: {childName: 'PageLayout.Header', parentName: 'PageLayout'}
+        }
+      ]
+    },
+    {
+      code: `import {TreeView} from '@primer/react'; <TreeView><TreeView.Item><div><TreeView.LeadingVisual>Visual</TreeView.LeadingVisual></div></TreeView.Item></TreeView>`,
+      errors: [
+        {
+          messageId: 'directSlotChildren',
+          data: {childName: 'TreeView.LeadingVisual', parentName: 'TreeView.Item'}
+        }
+      ]
+    }
+  ]
+})

src/rules/direct-slot-children.js

@@ -0,0 +1,60 @@
+const {isPrimerComponent} = require('../utils/is-primer-component')
+
+const slotParentToChildMap = {
+  PageLayout: ['PageLayout.Header', 'PageLayout.Footer'],
+  FormControl: ['FormControl.Label', 'FormControl.Caption', 'FormControl.LeadingVisual', 'FormControl.TrailingVisual'],
+  MarkdownEditor: ['MarkdownEditor.Toolbar', 'MarkdownEditor.Actions', 'MarkdownEditor.Label'],
+  'ActionList.Item': ['ActionList.LeadingVisual', 'ActionList.TrailingVisual', 'ActionList.Description'],
+  'TreeView.Item': ['TreeView.LeadingVisual', 'TreeView.TrailingVisual'],
+  RadioGroup: ['RadioGroup.Label', 'RadioGroup.Caption', 'RadioGroup.Validation'],
+  CheckboxGroup: ['CheckboxGroup.Label', 'CheckboxGroup.Caption', 'CheckboxGroup.Validation']
+}
+
+const slotChildToParentMap = Object.entries(slotParentToChildMap).reduce((acc, [parent, children]) => {
+  for (const child of children) {
+    acc[child] = parent
+  }
+  return acc
+}, {})
+
+module.exports = {
+  meta: {
+    type: 'problem',
+    schema: [],
+    messages: {
+      directSlotChildren: '{{childName}} must be a direct child of {{parentName}}.'
+    }
+  },
+  create(context) {
+    return {
+      JSXOpeningElement(jsxNode) {
+        const name = getJSXOpeningElementName(jsxNode)
+
+        // If component is a Primer component and a slot child,
+        // check if it's a direct child of the slot parent
+        if (isPrimerComponent(jsxNode.name, context.getScope(jsxNode)) && slotChildToParentMap[name]) {
+          const JSXElement = jsxNode.parent
+          const parent = JSXElement.parent
+
+          const expectedParentName = slotChildToParentMap[name]
+          if (parent.type !== 'JSXElement' || getJSXOpeningElementName(parent.openingElement) !== expectedParentName) {
+            context.report({
+              node: jsxNode,
+              messageId: 'directSlotChildren',
+              data: {childName: name, parentName: expectedParentName}
+            })
+          }
+        }
+      }
+    }
+  }
+}
+
+// Convert JSXOpeningElement name to string
+function getJSXOpeningElementName(jsxNode) {
+  if (jsxNode.name.type === 'JSXIdentifier') {
+    return jsxNode.name.name
+  } else if (jsxNode.name.type === 'JSXMemberExpression') {
+    return `${jsxNode.name.object.name}.${jsxNode.name.property.name}`
+  }
+}

src/utils/is-primer-component.js

@@ -1,6 +1,19 @@
 const {isImportedFrom} = require('./is-imported-from')
 
-function isPrimerComponent(identifier, scope) {
+function isPrimerComponent(name, scope) {
+  let identifier
+
+  switch (name.type) {
+    case 'JSXIdentifier':
+      identifier = name
+      break
+    case 'JSXMemberExpression':
+      identifier = name.object
+      break
+    default:
+      return false
+  }
+
   return isImportedFrom(/^@primer\/react/, identifier, scope)
 }
 exports.isPrimerComponent = isPrimerComponent