Add maximumLineLength rule

This rule reports lines in Pug file that exceed the specified length.

Related to pugjs#3

docs/rules.md

@@ -333,6 +333,12 @@ h1= translate(`${title} text`)
 h1= translate(`${title} text`)
 ```
 
+# maximumLineLength: `int`
+
+## e.g.: `80`
+
+Lines in Pug file must not exceed the specified length.
+
 # maximumNumberOfLines: `int`
 
 Pug files should be at most the number of lines specified.

lib/rules/maximum-line-length.js

@@ -0,0 +1,33 @@
+// # maximumLineLength: `int`
+//
+// ## e.g.: `80`
+//
+// Lines in Pug file must not exceed the specified length.
+
+var assert = require('assert');
+
+module.exports = function () {};
+
+module.exports.prototype = {
+  name: 'maximumLineLength',
+
+  schema: {
+    type: ['null', 'integer']
+  },
+
+  configure: function (options) {
+    assert(typeof options === 'number', this.name + ' option requires number value or should be removed');
+
+    this._maximumLineLength = options;
+  },
+
+  lint: function (file, errors) {
+    var max = this._maximumLineLength;
+
+    file.getLines().forEach(function (line, index) {
+      if (line.length > max) {
+        errors.add('Line length exceeds the maximum of ' + max + ' chars', index + 1);
+      }
+    });
+  }
+};

schemas/pug-lintrc-schema.json

@@ -243,6 +243,14 @@
             "description": "Pug must not contain template strings. `true` only fails when a template\nstring is used directly; `'all'` fails when template strings are used at\nall.",
             "documentation": "# disallowTemplateString: `true` | `'all'`\n\nPug must not contain template strings. `true` only fails when a template\nstring is used directly; `'all'` fails when template strings are used at\nall.\n\n## e.g. `true`\n\n```pug\n//- Invalid\nh1= `${title} text`\n\n//- Valid\nh1= translate(`${title} text`)\n```\n\n## e.g. `'all'`\n\n```pug\n//- Invalid\nh1= translate(`${title} text`)\n```\n"
         },
+        "maximumLineLength": {
+            "type": [
+                "null",
+                "integer"
+            ],
+            "description": "Lines in Pug file must not exceed the specified length.",
+            "documentation": "# maximumLineLength: `int`\n\n## e.g.: `80`\n\nLines in Pug file must not exceed the specified length.\n"
+        },
         "maximumNumberOfLines": {
             "type": [
                 "null",

test/rules/maximum-line-length.test.js

@@ -0,0 +1,48 @@
+module.exports = createTest;
+
+var assert = require('assert');
+
+function createTest(linter) {
+  describe('maximumLineLength', function () {
+    describe('int', function () {
+      before(function () {
+        linter.configure({maximumLineLength: 40});
+      });
+
+      var ok = 'html\n' +
+               '  body\n' +
+               '    div This is a 40-char-long line ----\n' +
+               '    p other line\n';
+      var notOk = 'html\n' +
+                  '  body\n' +
+                  '    div This is a 41-char-long line -----\n' +
+                  '    p other line\n';
+      var notOk2 = 'html\n' +
+                   '  body\n' +
+                   '    div This is a 41-char-long line -----\n' +
+                   '    p other line\n' +
+                   '    div This is a 45-char-long line ---------\n' +
+                   '    p other line\n';
+
+      it('should not report normal lines', function () {
+        assert.equal(linter.checkString(ok).length, 0);
+      });
+
+      it('should report lines too long', function () {
+        assert.equal(linter.checkString(notOk).length, 1);
+      });
+
+      it('should report multiple errors', function () {
+        var result = linter.checkString(notOk2);
+
+        assert.equal(result.length, 2);
+        assert.equal(result[0].code, 'PUG:LINT_MAXIMUMLINELENGTH');
+        assert.equal(result[0].line, 3);
+        assert.equal(result[0].column, undefined);
+        assert.equal(result[1].code, 'PUG:LINT_MAXIMUMLINELENGTH');
+        assert.equal(result[1].line, 5);
+        assert.equal(result[1].column, undefined);
+      });
+    });
+  });
+}