Merge pull request #2592 from NullVoxPopuli/nvp/template-lint-extract-rule-template-no-whitespace-for-layout

Extract rule: template-no-whitespace-for-layout

Author: NullVoxPopuli

README.md

@@ -255,6 +255,7 @@ rules in templates can be disabled with eslint directives with mustache or html
 | [template-no-obsolete-elements](docs/rules/template-no-obsolete-elements.md)                                       | disallow obsolete HTML elements                                              |    |    |    |
 | [template-no-outlet-outside-routes](docs/rules/template-no-outlet-outside-routes.md)                               | disallow {{outlet}} outside of route templates                               |    |    |    |
 | [template-no-page-title-component](docs/rules/template-no-page-title-component.md)                                 | disallow usage of ember-page-title component                                 |    |    |    |
+| [template-no-whitespace-for-layout](docs/rules/template-no-whitespace-for-layout.md)                               | disallow using whitespace for layout purposes                                |    |    |    |
 | [template-no-yield-block-params-to-else-inverse](docs/rules/template-no-yield-block-params-to-else-inverse.md)     | disallow yielding block params to else or inverse block                      |    |    |    |
 | [template-no-yield-only](docs/rules/template-no-yield-only.md)                                                     | disallow components that only yield                                          |    |    |    |
 | [template-no-yield-to-default](docs/rules/template-no-yield-to-default.md)                                         | disallow yield to default block                                              |    |    |    |

docs/rules/template-no-whitespace-for-layout.md

@@ -0,0 +1,46 @@
+# ember/template-no-whitespace-for-layout
+
+<!-- end auto-generated rule header -->
+
+Formatting of text through the use of multiple whitespace is entirely visual, and therefore is incompatible with screen-reading assistive technology tools.
+
+The rule applies to the content of Handlebars AST TextNodes, and performs a RegExp search for two consecutive white space characters that might indicate the use of whitespace used for layout.
+
+## Examples
+
+This rule **forbids** the following:
+
+```gjs
+<template>
+  Mon.&nbsp;&nbsp;&nbsp;&nbsp;Eggs&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Tomato soup&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;House salad<br>
+  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Bacon&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Hamburger&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Fried chicken<br>
+  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Toast&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Onion rings&nbsp;&nbsp;&nbsp;&nbsp;Green beans<br>
+  &nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Cookie&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;Mashed potatoes
+</template>
+```
+
+This rule **allows** the following:
+
+```gjs
+<template>
+  <p>Start to finish</p>
+</template>
+```
+
+```gjs
+<template>
+  <p>Start&nbsp;to&nbsp;Finish</p>
+</template>
+```
+
+## Migration
+
+To fix issues caused by using whitespace for layout, the following are recommended:
+
+- use the appropriate HTML markup to contain the information
+- use CSS to add padding or margins to the semantic HTML markup
+
+## References
+
+- [F33: Using white space characters to create multiple columns in plain text content](https://www.w3.org/TR/WCAG20-TECHS/failures.html#F33)
+- [F34: Using white space characters to format tables in plain text content](https://www.w3.org/TR/WCAG20-TECHS/failures.html#F34)

lib/rules/template-no-whitespace-for-layout.js

@@ -0,0 +1,52 @@
+/** @type {import('eslint').Rule.RuleModule} */
+const ERROR_MESSAGE = 'Excess whitespace detected.';
+
+module.exports = {
+  meta: {
+    type: 'suggestion',
+    docs: {
+      description: 'disallow using whitespace for layout purposes',
+      category: 'Best Practices',
+      url: 'https://github.com/ember-cli/eslint-plugin-ember/tree/master/docs/rules/template-no-whitespace-for-layout.md',
+      templateMode: 'both',
+    },
+    schema: [],
+    messages: {
+      noWhitespaceForLayout: ERROR_MESSAGE,
+    },
+    originallyFrom: {
+      name: 'ember-template-lint',
+      rule: 'lib/rules/no-whitespace-for-layout.js',
+      docs: 'docs/rule/no-whitespace-for-layout.md',
+      tests: 'test/unit/rules/no-whitespace-for-layout-test.js',
+    },
+  },
+
+  create(context) {
+    const sourceCode = context.getSourceCode();
+
+    return {
+      GlimmerTextNode(node) {
+        const text = sourceCode.getText(node);
+        if (!text) {
+          return;
+        }
+
+        const lines = text.split('\n');
+        for (const line of lines) {
+          // Ignore whitespace at the start and end of the line
+          const trimmed = line.trim();
+
+          // Check for two consecutive ` ` or ` ` in a row
+          if (/(( )|( ))(( )|( ))/.test(trimmed)) {
+            context.report({
+              node,
+              messageId: 'noWhitespaceForLayout',
+            });
+            return;
+          }
+        }
+      },
+    };
+  },
+};

tests/lib/rules/template-no-whitespace-for-layout.js

@@ -0,0 +1,79 @@
+//------------------------------------------------------------------------------
+// Requirements
+//------------------------------------------------------------------------------
+
+const rule = require('../../../lib/rules/template-no-whitespace-for-layout');
+const RuleTester = require('eslint').RuleTester;
+
+const validHbs = [
+  'Start to finish',
+  'Start to finish',
+  'Start<br>to<br>finish',
+  `<div>
+  example
+</div>`,
+  `<div
+  foo="bar"
+  baz="qux"
+>
+  example
+</div>`,
+];
+
+const invalidHbs = [
+  {
+    code: 'START  FINISH',
+    output: null,
+    errors: [{ message: 'Excess whitespace detected.' }],
+  },
+  {
+    code: 'START&nbsp;&nbsp;FINISH',
+    output: null,
+    errors: [{ message: 'Excess whitespace detected.' }],
+  },
+  {
+    code: 'START&nbsp; FINISH',
+    output: null,
+    errors: [{ message: 'Excess whitespace detected.' }],
+  },
+  {
+    code: 'START &nbsp;FINISH',
+    output: null,
+    errors: [{ message: 'Excess whitespace detected.' }],
+  },
+];
+
+function wrapTemplate(entry) {
+  if (typeof entry === 'string') {
+    return `<template>${entry}</template>`;
+  }
+
+  return {
+    ...entry,
+    code: `<template>${entry.code}</template>`,
+    output: entry.output ? `<template>${entry.output}</template>` : entry.output,
+  };
+}
+
+const gjsRuleTester = new RuleTester({
+  parser: require.resolve('ember-eslint-parser'),
+  parserOptions: { ecmaVersion: 2022, sourceType: 'module' },
+});
+
+gjsRuleTester.run('template-no-whitespace-for-layout', rule, {
+  valid: validHbs.map(wrapTemplate),
+  invalid: invalidHbs.map(wrapTemplate),
+});
+
+const hbsRuleTester = new RuleTester({
+  parser: require.resolve('ember-eslint-parser/hbs'),
+  parserOptions: {
+    ecmaVersion: 2022,
+    sourceType: 'module',
+  },
+});
+
+hbsRuleTester.run('template-no-whitespace-for-layout', rule, {
+  valid: validHbs,
+  invalid: invalidHbs,
+});