Add rule: declarations before nesting

docs/rules/declarations-before-nesting.md

@@ -0,0 +1,29 @@
+# Declarations Before Nesting
+
+Rule `declarations-before-nesting` will enforce that declarations should be written before nesting in a ruleset.
+
+## Examples
+
+When enabled, the following are allowed:
+
+```scss
+.foo {
+  content: 'baz';
+
+  .bar {
+    content: 'qux';
+  }
+}
+```
+
+When enabled, the following are disallowed:
+
+```scss
+.foo {
+  .bar {
+    content: 'qux';
+  }
+
+  content: 'baz';
+}
+```

lib/config/sass-lint.yml

@@ -45,6 +45,7 @@ rules:
   property-units: 0
 
   # Nesting
+  declarations-before-nesting: 1
   force-attribute-nesting: 1
   force-element-nesting: 1
   force-pseudo-nesting: 1

lib/rules/declarations-before-nesting.js

@@ -0,0 +1,47 @@
+'use strict';
+
+var helpers = require('../helpers');
+
+module.exports = {
+  'name': 'declarations-before-nesting',
+  'defaults': {},
+  'detect': function (ast, parser) {
+    var result = [],
+        error;
+
+    ast.traverseByType('block', function (block) {
+      if (block.contains('ruleset') && block.contains('declaration')) {
+        var rulesetIndex;
+
+        block.forEach(function (item, j) {
+          var declarationIndex;
+          var declaration;
+
+          if (item.is('ruleset') && rulesetIndex === void 0) {
+            rulesetIndex = j;
+          }
+
+          if (item.is('declaration')) {
+            declarationIndex = j;
+            declaration = item;
+          }
+
+          if (rulesetIndex < declarationIndex && declaration) {
+            error = {
+              'ruleId': parser.rule.name,
+              'line': declaration.start.line,
+              'column': declaration.start.column,
+              'message': 'Declarations should come before nestings',
+              'severity': parser.severity
+            };
+            result = helpers.addUnique(result, error);
+          }
+        });
+
+        rulesetIndex = null;
+      }
+    });
+
+    return result;
+  }
+};

tests/rules/declarations-before-nesting.js

@@ -0,0 +1,36 @@
+'use strict';
+
+var lint = require('./_lint');
+
+//////////////////////////////
+// SCSS syntax tests
+//////////////////////////////
+describe('declarations before nesting - scss', function () {
+  var file = lint.file('declarations-before-nesting.scss');
+
+  it('enforce', function (done) {
+    lint.test(file, {
+      'declarations-before-nesting': 1
+    }, function (data) {
+      console.log(data);
+      lint.assert.equal(4, data.warningCount);
+      done();
+    });
+  });
+});
+
+//////////////////////////////
+// Sass syntax tests
+//////////////////////////////
+describe('declarations before nesting - sass', function () {
+  var file = lint.file('declarations-before-nesting.sass');
+
+  it('enforce', function (done) {
+    lint.test(file, {
+      'declarations-before-nesting': 1
+    }, function (data) {
+      lint.assert.equal(4, data.warningCount);
+      done();
+    });
+  });
+});

tests/sass/declarations-before-nesting.sass

@@ -0,0 +1,27 @@
+.bar
+  content: 'baz'
+
+  .qux
+    content: 'baz'
+
+.foo
+  .bar
+    content: 'where'
+
+  content: 'baz'
+
+  .baz
+    content: 'where'
+
+  content: 'baz'
+
+.foo
+  .bar
+    content: 'where'
+
+    .baz
+      content: 'quz'
+
+    content: 'baz'
+
+  content: 'baz'

tests/sass/declarations-before-nesting.scss

@@ -0,0 +1,35 @@
+.bar {
+  content: 'baz';
+
+  .qux {
+    content: 'baz';
+  }
+}
+
+.foo {
+  .bar {
+    content: 'where';
+  }
+
+  content: 'baz';
+
+  .baz {
+    content: 'where';
+  }
+
+  content: 'baz';
+}
+
+.foo {
+  .bar {
+    content: 'where';
+
+    .baz {
+      content: 'quz';
+    }
+
+    content: 'baz';
+  }
+
+  content: 'baz';
+}