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Extract rule: template-no-multiple-empty-lines
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‎README.md‎

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@@ -210,6 +210,7 @@ rules in templates can be disabled with eslint directives with mustache or html
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| [template-no-input-placeholder](docs/rules/template-no-input-placeholder.md) | disallow placeholder attribute on input elements | | | |
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| [template-no-input-tagname](docs/rules/template-no-input-tagname.md) | disallow tagName attribute on {{input}} helper | | | |
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| [template-no-log](docs/rules/template-no-log.md) | disallow {{log}} in templates | | | |
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| [template-no-multiple-empty-lines](docs/rules/template-no-multiple-empty-lines.md) | disallow multiple consecutive empty lines in templates | | | |
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| [template-no-mut-helper](docs/rules/template-no-mut-helper.md) | disallow usage of (mut) helper | | | |
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| [template-no-negated-comparison](docs/rules/template-no-negated-comparison.md) | disallow negated comparisons in templates | | | |
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| [template-no-negated-condition](docs/rules/template-no-negated-condition.md) | disallow negated conditions in if/unless | | | |

‎docs/rules/template-no-multiple-empty-lines.md‎

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# ember/template-no-multiple-empty-lines
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<!-- end auto-generated rule header -->
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Disallows multiple consecutive empty lines in templates.
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Multiple consecutive blank lines reduce readability and should be limited.
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## Rule Details
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This rule enforces a maximum number of consecutive empty lines (default: 1).
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## Configuration
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The following values are valid configuration:
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- object -- An object with the following keys:
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- `max` -- An integer specifying the maximum number of consecutive empty lines allowed. Defaults to `1`.
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## Examples
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Examples of **incorrect** code for this rule:
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```gjs
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<template>
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<div>First</div>
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<div>Second</div>
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</template>
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```
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```gjs
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<template>
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<div>Content</div>
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<div>More content</div>
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</template>
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```
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Examples of **correct** code for this rule:
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```gjs
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<template>
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<div>First</div>
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<div>Second</div>
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</template>
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```
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```gjs
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<template>
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<div>Content</div>
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<div>More content</div>
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</template>
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```
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## References
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- [eslint-plugin-ember template-no-multiple-empty-lines](https://github.com/ember-cli/eslint-plugin-ember/blob/master/docs/rules/template-no-multiple-empty-lines.md)
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- [ESLint no-multiple-empty-lines](https://eslint.org/docs/rules/no-multiple-empty-lines)

‎lib/rules/template-no-multiple-empty-lines.js‎

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/** @type {import('eslint').Rule.RuleModule} */
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module.exports = {
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meta: {
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type: 'suggestion',
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docs: {
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description: 'disallow multiple consecutive empty lines in templates',
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category: 'Best Practices',
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url: 'https://github.com/ember-cli/eslint-plugin-ember/tree/master/docs/rules/template-no-multiple-empty-lines.md',
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templateMode: 'both',
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},
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fixable: null,
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schema: [
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{
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type: 'object',
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properties: {
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max: {
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type: 'integer',
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minimum: 0,
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},
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},
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additionalProperties: false,
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},
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],
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messages: {
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unexpected: 'More than {{max}} blank {{pluralizedLines}} not allowed.',
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},
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originallyFrom: {
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name: 'ember-template-lint',
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rule: 'lib/rules/no-multiple-empty-lines.js',
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docs: 'docs/rule/no-multiple-empty-lines.md',
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tests: 'test/unit/rules/no-multiple-empty-lines-test.js',
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},
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},
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create(context) {
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const max = context.options[0]?.max ?? 1;
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const sourceCode = context.sourceCode;
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return {
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Program(node) {
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const text = sourceCode.getText();
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const lines = text.split('\n');
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let emptyCount = 0;
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let firstEmptyLine = -1;
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for (const [index, line] of lines.entries()) {
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if (line.trim() === '') {
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if (emptyCount === 0) {
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firstEmptyLine = index;
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}
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emptyCount++;
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} else {
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if (emptyCount > max) {
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const startLine = firstEmptyLine + max + 1;
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const endLine = index;
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context.report({
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loc: {
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start: { line: startLine + 1, column: 0 },
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end: { line: endLine, column: 0 },
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},
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messageId: 'unexpected',
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data: {
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max,
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pluralizedLines: max === 1 ? 'line' : 'lines',
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},
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});
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}
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emptyCount = 0;
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firstEmptyLine = -1;
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}
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}
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},
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};
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},
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};

‎tests/lib/rules/template-no-multiple-empty-lines.js‎

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//------------------------------------------------------------------------------
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// Requirements
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//------------------------------------------------------------------------------
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const rule = require('../../../lib/rules/template-no-multiple-empty-lines');
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const RuleTester = require('eslint').RuleTester;
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//------------------------------------------------------------------------------
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// Tests
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//------------------------------------------------------------------------------
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const ruleTester = new RuleTester({
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parser: require.resolve('ember-eslint-parser'),
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parserOptions: { ecmaVersion: 2022, sourceType: 'module' },
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});
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ruleTester.run('template-no-multiple-empty-lines', rule, {
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valid: [
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`<template>
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<div>Hello</div>
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<div>World</div>
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</template>`,
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{
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code: `<template>
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<div>Hello</div>
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<div>World</div>
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</template>`,
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options: [{ max: 2 }],
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},
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`<template>
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<div>Content</div>
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</template>`,
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'<template><div>foo</div><div>bar</div></template>',
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`<template><div>foo</div>
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<div>bar</div></template>`,
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`<template><div>foo</div>r
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<div>bar</div></template>`,
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`<template><div>foo</div>
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<div>bar</div></template>`,
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`<template><div>foo</div>r
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r
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<div>bar</div></template>`,
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`<template>
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<div>foo</div>
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<div>bar</div>
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</template>`,
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],
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invalid: [
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{
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code: `<template>
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<div>Hello</div>
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<div>World</div>
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</template>`,
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output: null,
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errors: [
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{
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message: 'More than 1 blank line not allowed.',
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},
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],
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},
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{
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code: `<template>
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<div>First</div>
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<div>Second</div>
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</template>`,
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output: null,
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errors: [
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{
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message: 'More than 1 blank line not allowed.',
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},
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],
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},
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{
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code: `<template><div>foo</div>
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<div>bar</div></template>`,
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output: null,
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errors: [{ message: 'More than 1 blank line not allowed.' }],
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},
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{
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code: `<template><div>foo</div>
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<div>bar</div></template>`,
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output: null,
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errors: [{ message: 'More than 1 blank line not allowed.' }],
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},
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],
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});
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const hbsRuleTester = new RuleTester({
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parser: require.resolve('ember-eslint-parser/hbs'),
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parserOptions: {
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ecmaVersion: 2022,
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sourceType: 'module',
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},
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});
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hbsRuleTester.run('template-no-multiple-empty-lines', rule, {
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valid: [
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'<div>foo</div><div>bar</div>',
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`<div>foo</div>
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<div>bar</div>`,
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`<div>foo</div>
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<div>bar</div>`,
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`
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<div>foo</div>
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<div>bar</div>
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`,
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'<div>foo</div>\r\n<div>bar</div>',
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'<div>foo</div>\r\n\r\n<div>bar</div>',
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{
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code: '<div>foo</div>\n\n\n<div>bar</div>',
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options: [{ max: 2 }],
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},
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{
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code: '<div>foo</div>\r\n\r\n\r\n<div>bar</div>',
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options: [{ max: 2 }],
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},
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],
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invalid: [
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{
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code: `<div>foo</div>
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<div>bar</div>`,
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output: null,
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errors: [{ message: 'More than 1 blank line not allowed.' }],
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},
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{
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code: `<div>foo</div>
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<div>bar</div>`,
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output: null,
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errors: [{ message: 'More than 1 blank line not allowed.' }],
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},
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{
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code: '<div>foo</div>\n\n\n\n\n<div>bar</div>',
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output: null,
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options: [{ max: 3 }],
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errors: [{ message: 'More than 3 blank lines not allowed.' }],
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},
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],
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});

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