requirePaddingNewLinesBeforeExport: exclude if only statement in block

Fixes #1883
Closes gh-2106

Author: schempy

lib/rules/require-padding-newlines-before-export.js

@@ -17,13 +17,22 @@
  * var a = 2;
  *
  * module.exports = a;
+ *
+ * if (cond) {
+ *    module.exports = a;
+ * }
  * ```
  *
  * ##### Invalid
  *
  * ```js
  * var a = 2;
  * module.exports = a;
+ *
+ * if (cond) {
+ *    foo();
+ *    module.exports = a;
+ * }
  * ```
  */
 
@@ -47,6 +56,7 @@ module.exports.prototype = {
     check: function(file, errors) {
         file.iterateNodesByType('AssignmentExpression', function(node) {
             var left = node.left;
+            var greatGrandpa = node.parentNode.parentNode;
             if (!(
                 left.object &&
                 left.object.name === 'module' &&
@@ -55,6 +65,11 @@ module.exports.prototype = {
                 return;
             }
 
+            // module.exports is in a block and is the only statement.
+            if (greatGrandpa.type === 'BlockStatement' && greatGrandpa.body.length === 1) {
+                return;
+            }
+
             var firstToken = file.getFirstNodeToken(node);
             var prevToken = file.getPrevToken(firstToken);
 
@@ -65,6 +80,7 @@ module.exports.prototype = {
                 message: 'Missing newline before export'
             });
         });
+
     }
 
 };

test/specs/rules/require-padding-newlines-before-export.js

@@ -31,5 +31,9 @@ describe('rules/require-padding-newlines-before-export', function() {
             expect(checker.checkString('var a = 2;\nfoo.exports = a;')).to.have.no.errors();
             expect(checker.checkString('var a = 2;\nmodule.foo = a;')).to.have.no.errors();
         });
+
+        it('should not report missing padding if export is only statement in block', function() {
+            expect(checker.checkString('if (true) {\nmodule.exports = a;\n}')).to.have.no.errors();
+        });
     });
 });