disallowMultipleVarDecl: improve {"allExcept": ["require"]} logic

When using `{"allExcept": ["require"]}`,
allow any declarion that sourced from a require call

Fixes #1848
Closes gh-1849

Author: ValYouW

lib/rules/disallow-multiple-var-decl.js

@@ -107,6 +107,29 @@ module.exports.prototype = {
     },
 
     check: function(file, errors) {
+
+        function isSourcedFromRequire(node) {
+            // If this node is a CallExpression it has a callee,
+            // check if this is the `require` function
+            if (node.callee && node.callee.name === 'require') {
+                return true;
+            }
+
+            // If this CallExpression is not a `require` we keep looking for
+            // the `require` method up in the tree
+            if (node.callee && node.callee.object) {
+                return isSourcedFromRequire(node.callee.object);
+            }
+
+            // If there is no `callee` this might be a MemberExpression, keep
+            // look for the `require` method up in the tree.
+            if (node.object) {
+                return isSourcedFromRequire(node.object);
+            }
+
+            return false;
+        }
+
         var inStrictMode = this._strictMode;
         var exceptUndefined = this._exceptUndefined;
         var exceptRequire = this._exceptRequire;
@@ -119,10 +142,7 @@ module.exports.prototype = {
 
             var requireStatements = node.declarations.filter(function(declaration) {
                 var init = declaration.init;
-
-                return init &&
-                    init.callee &&
-                    init.callee.name === 'require';
+                return init && isSourcedFromRequire(init);
             });
             var allRequireStatements = requireStatements.length === node.declarations.length;
 
@@ -160,5 +180,4 @@ module.exports.prototype = {
             errors.add('Multiple var declaration', node.loc.start);
         });
     }
-
 };

test/specs/rules/disallow-multiple-var-decl.js

@@ -96,13 +96,28 @@ describe('rules/disallow-multiple-var-decl', function() {
         it('should report multiple var decls with require mixed with normal', function() {
             expect(checker.checkString('var first = require("first"), second = 1;'))
               .to.have.one.validation.error.from('disallowMultipleVarDecl');
+
+            var test = 'var first = require("first"), second = 1, third = require("foo").Foo';
+            expect(checker.checkString(test)).to.have.one.validation.error.from('disallowMultipleVarDecl');
+        });
+        it('should report multiple var decls with require mixed with undefined', function() {
+            var test = 'var first = require("first"), second = require("foo").Foo, third;';
+            expect(checker.checkString(test)).to.have.one.validation.error.from('disallowMultipleVarDecl');
         });
         it('should report multiple var decls', function() {
             expect(checker.checkString('var x, y;')).to.have.one.validation.error.from('disallowMultipleVarDecl');
         });
         it('should not report consecutive var decls', function() {
             expect(checker.checkString('var x; var y;')).to.have.no.errors();
         });
+        it('should not report multiple var decls sourced from required', function() {
+            expect(checker.checkString('var x = require("fs"), y = require("fs").File;')).to.have.no.errors();
+            expect(checker.checkString('var x = require("fs").File, y = require("fs").foo();')).to.have.no.errors();
+            expect(checker.checkString('var x = require("fs"), y = require("fs").some.long().chain.test();'))
+                .to.have.no.errors();
+            expect(checker.checkString('var x = require("fs"), y = require("fs").some().long().chain.test;'))
+                .to.have.no.errors();
+        });
     });
 
     describe('options as object', function() {
@@ -114,8 +129,8 @@ describe('rules/disallow-multiple-var-decl', function() {
         it('should accept require and undefined as allExcept value', function() {
             checker.configure({ disallowMultipleVarDecl: { allExcept: ['undefined', 'require'] } });
 
-            expect(checker.checkString('var a = require("a"), b = require("b"), x, y, z;')).to.have.no.errors();
-            expect(checker.checkString('var a = require("a"), b = require("b"), x, y, c = 1;'))
+            expect(checker.checkString('var a = require("a"), b = require("b").getMe(), x, y, z;')).to.have.no.errors();
+            expect(checker.checkString('var a = require("a").Instance, b = require("b"), x, y, c = 1;'))
               .to.have.one.validation.error.from('disallowMultipleVarDecl');
         });
         it('should accept strict as option', function() {