Add awesome/heading rule (#70)

Author: itaisteinherz

rules/heading.js

@@ -0,0 +1,49 @@
+'use strict';
+const rule = require('unified-lint-rule');
+const visit = require('unist-util-visit');
+const {of: caseOf, title: titleCase} = require('case');
+
+const listHeadingCaseWhitelist = new Set([
+	'title',
+	'capital'
+]);
+
+module.exports = rule('remark-lint:awesome/heading', (ast, file) => {
+	let headings = 0;
+
+	visit(ast, (node, index) => {
+		if (node.type !== 'heading') {
+			return;
+		}
+
+		if (node.depth > 1) {
+			if (index !== 0) {
+				return;
+			}
+
+			file.message('Main list heading must be of depth 1', node);
+		}
+
+		for (const child of node.children) {
+			if (child.type !== 'text') {
+				continue;
+			}
+
+			const headingText = child.value;
+
+			if (!listHeadingCaseWhitelist.has(caseOf(headingText)) && titleCase(headingText) !== headingText) {
+				file.message('Main heading must be in title case', node);
+			}
+		}
+
+		headings++;
+
+		if (headings > 1) {
+			file.message('List can only have one heading', node);
+		}
+	});
+
+	if (headings === 0) {
+		file.message('Missing main list heading');
+	}
+});

rules/index.js

@@ -1,6 +1,7 @@
 'use strict';
 
 module.exports = [
+	require('./heading'),
 	require('./badge'),
 	require('./contributing'),
 	require('./git-repo-age'),

test/fixtures/heading/error0.md

@@ -0,0 +1 @@
+> This is an awesome list!

test/fixtures/heading/error1.md

@@ -0,0 +1,3 @@
+# my-awesome-list
+
+> This is an awesome list!

test/fixtures/heading/error2.md

@@ -0,0 +1,3 @@
+# Awesome List
+
+# This Is a Really Awesome List

test/fixtures/heading/error3.md

@@ -0,0 +1 @@
+## Improper Awesome List

test/fixtures/heading/success0.md

@@ -0,0 +1,3 @@
+# My Awesome List
+
+> This is an awesome list

test/fixtures/heading/success1.md

@@ -0,0 +1 @@
+# AHA Acronyms Are Allowed

test/rules/heading.js

@@ -0,0 +1,59 @@
+import test from 'ava';
+import lint from '../_lint';
+
+const config = {
+	plugins: [
+		require('remark-lint'),
+		require('../../rules/heading')
+	]
+};
+
+test('heading - missing', async t => {
+	const messages = await lint({config, filename: 'test/fixtures/heading/error0.md'});
+	t.deepEqual(messages, [
+		{
+			ruleId: 'awesome/heading',
+			message: 'Missing main list heading'
+		}
+	]);
+});
+
+test('heading - not in title case', async t => {
+	const messages = await lint({config, filename: 'test/fixtures/heading/error1.md'});
+	t.deepEqual(messages, [
+		{
+			ruleId: 'awesome/heading',
+			message: 'Main heading must be in title case'
+		}
+	]);
+});
+
+test('heading - more than one heading', async t => {
+	const messages = await lint({config, filename: 'test/fixtures/heading/error2.md'});
+	t.deepEqual(messages, [
+		{
+			ruleId: 'awesome/heading',
+			message: 'List can only have one heading'
+		}
+	]);
+});
+
+test('heading - depth is bigger than 1', async t => {
+	const messages = await lint({config, filename: 'test/fixtures/heading/error3.md'});
+	t.deepEqual(messages, [
+		{
+			ruleId: 'awesome/heading',
+			message: 'Main list heading must be of depth 1'
+		}
+	]);
+});
+
+test('heading - success', async t => {
+	const messages = await lint({config, filename: 'test/fixtures/heading/success0.md'});
+	t.deepEqual(messages, []);
+});
+
+test('heading - success (with acronyms)', async t => {
+	const messages = await lint({config, filename: 'test/fixtures/heading/success1.md'});
+	t.deepEqual(messages, []);
+});