Introduce a new rule to flag Link in text blocks without inline

.changeset/happy-parents-invite.md

@@ -0,0 +1,5 @@
+---
+"eslint-plugin-primer-react": patch
+---
+
+New rule to flag `Link` in text block missing the `inline` prop

docs/rules/a11y-link-in-text-block.md

@@ -0,0 +1,100 @@
+## Require `inline` prop on `<Link>` component inside a text block
+
+The `Link` component should have the `inline` prop when it is used inside of a text block.
+
+## Rule Details
+
+This rule enforces setting `inline` on the `<Link>` component when a `<Link>` is detected inside of a text block without distiguishable styling.
+
+The lint rule will essentially flag any `<Link>` without the `inline` property (equal to `true`) detected with string nodes on either side.
+
+This rule will not catch all instances of link in text block due to the limitations of static analysis, so be sure to also have in-browser checks in place such as the [link-in-text-block Axe rule](https://dequeuniversity.com/rules/axe/4.9/link-in-text-block) for additional coverage.
+
+The edge cases that the linter skips to avoid false positives will include:
+
+- `<Link sx={{fontWeight:...}}>` or `<Link sx={{fontFamily:...}}>` because these technically may provide sufficient distinguishing styling.
+- `<Link>` where the only adjacent text is a period, since that can't really be considered a text block.
+- `<Link>` where the children is a JSX component, rather than a string literal, because then it might be an icon link rather than a text link.
+- `<Link>` that are nested inside of headings as these have often been breadcrumbs.
+
+👎 Examples of **incorrect** code for this rule
+
+```jsx
+import {Link} from '@primer/react'
+
+function ExampleComponent() {
+  return (
+    <SomeComponent>
+      <Link>Say hello</Link> or not.
+    </SomeComponent>
+  )
+}
+```
+
+```jsx
+import {Link} from '@primer/react'
+
+function ExampleComponent() {
+  return (
+    <SomeComponent>
+      Say hello or <Link>sign-up</Link>.
+    </SomeComponent>
+  )
+}
+```
+
+👍 Examples of **correct** code for this rule:
+
+```jsx
+function ExampleComponent() {
+  return (
+    <SomeComponent>
+      <Link inline>Say hello</Link> or not.
+    </SomeComponent>
+  )
+}
+```
+
+```jsx
+function ExampleComponent() {
+  return (
+    <SomeComponent>
+      <Link inline={true}>Say hello</Link> or not.
+    </SomeComponent>
+  )
+}
+```
+
+This rule will skip `Link`s containing JSX elements to minimize potential false positives because it is possible the JSX element sufficiently distinguishes the link from surrounding text.
+
+```jsx
+function ExampleComponent() {
+  return (
+    <SomeComponent>
+      <Link>
+        <SomeAvatar />
+        @monalisa
+      </Link>{' '}
+      commented on your account.
+    </SomeComponent>
+  )
+}
+```
+
+This rule will skip `Link`s nested inside of a `Heading`.
+
+```jsx
+function ExampleComponent() {
+  return (
+    <Heading>
+      <Link>Previous location</Link>/ Current location
+    </Heading>
+  )
+}
+```
+
+## Options
+
+- `skipImportCheck` (default: `false`)
+
+By default, the `a11y-explicit-heading` rule will only check for `<Heading>` components imported directly from `@primer/react`. You can disable this behavior by setting `skipImportCheck` to `true`.

src/index.js

@@ -7,6 +7,7 @@ module.exports = {
     'new-color-css-vars': require('./rules/new-color-css-vars'),
     'a11y-explicit-heading': require('./rules/a11y-explicit-heading'),
     'no-deprecated-props': require('./rules/no-deprecated-props'),
+    'a11y-link-in-text-block': require('./rules/a11y-link-in-text-block'),
   },
   configs: {
     recommended: require('./configs/recommended'),

src/rules/__tests__/a11y-link-in-text-block.test.js

@@ -0,0 +1,161 @@
+const rule = require('../a11y-link-in-text-block')
+const {RuleTester} = require('eslint')
+
+const ruleTester = new RuleTester({
+  parserOptions: {
+    ecmaVersion: 'latest',
+    sourceType: 'module',
+    ecmaFeatures: {
+      jsx: true,
+    },
+  },
+})
+
+ruleTester.run('a11y-link-in-text-block', rule, {
+  valid: [
+    `import {Link} from '@primer/react';
+    <Box>
+
+    <Link href="something">
+      Blah blah
+    </Link>{' '}
+    . 
+    </Box>
+  `,
+    `import {Text, Link} from '@primer/react';
+  <Something>
+    <Link href='blah'>
+      blah
+    </Link>
+  </Something>
+  `,
+    `import {Link} from '@primer/react';
+    <p>bla blah <Link inline={true}>Link level 1</Link></p>;
+  `,
+    `import {Link} from '@primer/react';
+    <p>bla blah<Link inline>Link level 1</Link></p>;
+  `,
+    `import {Link} from '@primer/react';
+    <><span>something</span><Link inline={true}>Link level 1</Link></>;
+  `,
+    `import {Link} from '@primer/react';
+   <Link>Link level 1</Link>;
+`,
+    `import {Heading, Link} from '@primer/react';
+      <Heading>
+        <Link>Link level 1</Link>
+        hello
+      </Heading>
+`,
+    `import {Heading, Link} from '@primer/react';
+    <Heading as="h2">
+      <Link href={somePath}>
+        Breadcrumb
+      </Link>
+      Create a thing
+    </Heading>
+`,
+    `import {Link} from '@primer/react';
+    <div>
+    <h2>
+    <Link href={somePath}>
+      Breadcrumb
+    </Link>
+    </h2>
+    Create a thing
+    </div>
+`,
+    `import {Link} from '@primer/react';
+    <div>
+    <Link href={somePath}>
+      <GitHubAvatar />{owner}
+    </Link>{' '}
+    last edited{' '}
+    </div>
+`,
+    `import {Link} from '@primer/react';
+    <span>
+    by
+    <Link href="something" sx={{p: 2, fontWeight: 'bold'}}>
+      Blah blah
+    </Link>
+    </span>
+`,
+    `import {Link} from '@primer/react';
+    <span>
+    by
+    <Link href="something" sx={{fontWeight: 'bold'}}>
+      Blah blah
+    </Link>
+    </span>
+`,
+    `import {Link} from '@primer/react';
+  <span>
+  by
+  <Link href="something" sx={{fontFamily: 'mono'}}>
+    Blah blah
+  </Link>
+  </span>
+  `,
+    `import {Link} from '@primer/react';
+    <Box>
+
+    <Link href="something">
+      Blah blah
+    </Link>{' '}
+    .
+    </Box>
+`,
+    `import {Link} from '@primer/react';
+<Heading sx={{fontSize: 1, mb: 3}} as="h3">
+          In addition,{' '}
+          <Link href="https://github.com/pricing" target="_blank">
+            GitHub Team
+          </Link>{' '}
+          includes:
+        </Heading>
+`,
+  ],
+  invalid: [
+    {
+      code: `import {Link} from '@primer/react';
+      <p>bla blah<Link>Link level 1</Link></p>
+    `,
+      errors: [{messageId: 'linkInTextBlock'}],
+    },
+    {
+      code: `import {Link} from '@primer/react';
+      <p><Link>Link level 1</Link> something something</p>
+    `,
+      errors: [{messageId: 'linkInTextBlock'}],
+    },
+    {
+      code: `import {Link} from '@primer/react';
+      <p>bla blah<Link inline={false}>Link level 1</Link></p>
+    `,
+      errors: [{messageId: 'linkInTextBlock'}],
+    },
+    {
+      code: `import {Link} from '@primer/react';
+      <Box>Something something{' '}
+        <Link>Link level 1</Link>
+      </Box>
+    `,
+      errors: [{messageId: 'linkInTextBlock'}],
+    },
+    {
+      code: `import {Link} from '@primer/react';
+      <>blah blah blah{' '}
+      <Link>Link level 1</Link></>;
+    `,
+      errors: [{messageId: 'linkInTextBlock'}],
+    },
+    {
+      code: `import {Link} from '@primer/react';
+      <>blah blah blah{' '}
+      <Link underline>Link level 1</Link></>;
+    `,
+      errors: [{messageId: 'linkInTextBlock'}],
+    },
+  ],
+})

src/rules/a11y-link-in-text-block.js

@@ -0,0 +1,104 @@
+const {isPrimerComponent} = require('../utils/is-primer-component')
+const {getJSXOpeningElementName} = require('../utils/get-jsx-opening-element-name')
+const {getJSXOpeningElementAttribute} = require('../utils/get-jsx-opening-element-attribute')
+
+module.exports = {
+  meta: {
+    type: 'problem',
+    schema: [
+      {
+        properties: {
+          skipImportCheck: {
+            type: 'boolean',
+          },
+        },
+      },
+    ],
+    messages: {
+      linkInTextBlock: '<Link>s that are used within a text block should have the inline prop.',
+    },
+  },
+  create(context) {
+    const sourceCode = context.sourceCode ?? context.getSourceCode()
+    return {
+      JSXElement(node) {
+        const name = getJSXOpeningElementName(node.openingElement)
+        if (
+          isPrimerComponent(node.openingElement.name, sourceCode.getScope(node)) &&
+          name === 'Link' &&
+          node.parent.children
+        ) {
+          let siblings = node.parent.children
+          const parentName = node.parent.openingElement?.name?.name
+          // Skip if Link is nested inside of a heading.
+          const parentsToSkip = ['Heading', 'h1', 'h2', 'h3', 'h4', 'h5', 'h6']
+          if (parentsToSkip.includes(parentName)) return
+          if (siblings.length > 0) {
+            siblings = siblings.filter(childNode => {
+              return (
+                !(childNode.type === 'JSXText' && /^\s+$/.test(childNode.value)) &&
+                !(
+                  childNode.type === 'JSXExpressionContainer' &&
+                  childNode.expression.type === 'Literal' &&
+                  /^\s+$/.test(childNode.expression.value)
+                ) &&
+                !(childNode.type === 'Literal' && /^\s+$/.test(childNode.value))
+              )
+            })
+            const index = siblings.findIndex(childNode => {
+              return childNode.range === node.range
+            })
+            const prevSibling = siblings[index - 1]
+            const nextSibling = siblings[index + 1]
+
+            const prevSiblingIsText = prevSibling && prevSibling.type === 'JSXText'
+            const nextSiblingIsText = nextSibling && nextSibling.type === 'JSXText'
+            if (prevSiblingIsText || nextSiblingIsText) {
+              // Skip if the only text adjacent to the link is a period, then skip it.
+              if (!prevSiblingIsText && /^\s*\.+\s*$/.test(nextSibling.value)) {
+                return
+              }
+              const sxAttribute = getJSXOpeningElementAttribute(node.openingElement, 'sx')
+              const inlineAttribute = getJSXOpeningElementAttribute(node.openingElement, 'inline')
+
+              // Skip if Link child is a JSX element.
+              const jsxElementChildren = node.children.filter(child => {
+                return child.type === 'JSXElement'
+              })
+              if (jsxElementChildren.length > 0) return
+
+              // Skip if fontWeight or fontFamily is set via the sx prop since these may technically be considered sufficiently distinguishing styles that don't use color.
+              if (
+                sxAttribute &&
+                sxAttribute?.value?.expression &&
+                sxAttribute.value.expression.type === 'ObjectExpression' &&
+                sxAttribute.value.expression.properties &&
+                sxAttribute.value.expression.properties.length > 0
+              ) {
+                const fontStyleProperty = sxAttribute.value.expression.properties.filter(property => {
+                  return property.key.name === 'fontWeight' || property.key.name === 'fontFamily'
+                })
+                if (fontStyleProperty.length > 0) return
+              }
+              if (inlineAttribute) {
+                if (!inlineAttribute.value) {
+                  return
+                } else if (inlineAttribute.value.type === 'JSXExpressionContainer') {
+                  if (inlineAttribute.value.expression.type === 'Literal') {
+                    if (inlineAttribute.value.expression.value === true) {
+                      return
+                    }
+                  }
+                }
+              }
+              context.report({
+                node,
+                messageId: 'linkInTextBlock',
+              })
+            }
+          }
+        }
+      },
+    }
+  },
+}