From 1baae421490015946c5397cb428d47ef2be3f681 Mon Sep 17 00:00:00 2001
From: Andrew Casey <andrew.casey@microsoft.com>
Date: Fri, 9 Feb 2018 11:15:13 -0800
Subject: [PATCH] Handle variable declaration without initializer in Convert to
 ES6 Module

Fixes #21786
---
 src/services/refactors/convertToEs6Module.ts          |  9 ++++++---
 ...factorConvertToEs6Module_triggers_noInitializer.ts | 11 +++++++++++
 2 files changed, 17 insertions(+), 3 deletions(-)
 create mode 100644 tests/cases/fourslash/refactorConvertToEs6Module_triggers_noInitializer.ts

diff --git a/src/services/refactors/convertToEs6Module.ts b/src/services/refactors/convertToEs6Module.ts
index 65f9f58ccc4..f1f3c16b6bb 100644
--- a/src/services/refactors/convertToEs6Module.ts
+++ b/src/services/refactors/convertToEs6Module.ts
@@ -33,14 +33,17 @@ namespace ts.refactor {
                 return isExportsOrModuleExportsOrAlias(sourceFile, node as PropertyAccessExpression)
                     || isExportsOrModuleExportsOrAlias(sourceFile, (node as PropertyAccessExpression).expression);
             case SyntaxKind.VariableDeclarationList:
-                const decl = firstOrUndefined((node as VariableDeclarationList).declarations);
-                return !!decl && isExportsOrModuleExportsOrAlias(sourceFile, decl.initializer);
+                return isVariableDeclarationTriggerLocation(firstOrUndefined((node as VariableDeclarationList).declarations));
             case SyntaxKind.VariableDeclaration:
-                return isExportsOrModuleExportsOrAlias(sourceFile, (node as VariableDeclaration).initializer);
+                return isVariableDeclarationTriggerLocation(node as VariableDeclaration);
             default:
                 return isExpression(node) && isExportsOrModuleExportsOrAlias(sourceFile, node)
                     || !onSecondTry && isAtTriggerLocation(sourceFile, node.parent, /*onSecondTry*/ true);
         }
+
+        function isVariableDeclarationTriggerLocation(decl: VariableDeclaration | undefined) {
+            return !!decl && !!decl.initializer && isExportsOrModuleExportsOrAlias(sourceFile, decl.initializer);
+        }
     }
 
     function isAtTopLevelRequire(call: CallExpression): boolean {
diff --git a/tests/cases/fourslash/refactorConvertToEs6Module_triggers_noInitializer.ts b/tests/cases/fourslash/refactorConvertToEs6Module_triggers_noInitializer.ts
new file mode 100644
index 00000000000..23cbdd12aee
--- /dev/null
+++ b/tests/cases/fourslash/refactorConvertToEs6Module_triggers_noInitializer.ts
@@ -0,0 +1,11 @@
+/// <reference path='fourslash.ts' />
+
+// @allowJs: true
+
+// @Filename: /a.js
+/////*a*/const/*b*/ alias;
+////require("x");
+
+goTo.select("a", "b");
+verify.not.refactorAvailable("Convert to ES6 module");
+