From 53906f222fe4ae62652b83646d26a72ea0952e1d Mon Sep 17 00:00:00 2001
From: Nathan Shively-Sanders <293473+sandersn@users.noreply.github.com>
Date: Tue, 9 Oct 2018 13:17:54 -0700
Subject: [PATCH] containsTopLevelCommonjs:handle uninitialised vars (#27642)

Previously it assumed that all variable declarations had an initialiser,
which is not correct.
---
 src/services/suggestionDiagnostics.ts         |  2 +-
 ...oEs6Module_unexported_uninitialized_var.ts | 24 +++++++++++++++++++
 2 files changed, 25 insertions(+), 1 deletion(-)
 create mode 100644 tests/cases/fourslash/refactorConvertToEs6Module_unexported_uninitialized_var.ts

diff --git a/src/services/suggestionDiagnostics.ts b/src/services/suggestionDiagnostics.ts
index 291d607cee8..fcbb02d4023 100644
--- a/src/services/suggestionDiagnostics.ts
+++ b/src/services/suggestionDiagnostics.ts
@@ -82,7 +82,7 @@ namespace ts {
             switch (statement.kind) {
                 case SyntaxKind.VariableStatement:
                     return (statement as VariableStatement).declarationList.declarations.some(decl =>
-                        isRequireCall(propertyAccessLeftHandSide(decl.initializer!), /*checkArgumentIsStringLiteralLike*/ true)); // TODO: GH#18217
+                        !!decl.initializer && isRequireCall(propertyAccessLeftHandSide(decl.initializer), /*checkArgumentIsStringLiteralLike*/ true));
                 case SyntaxKind.ExpressionStatement: {
                     const { expression } = statement as ExpressionStatement;
                     if (!isBinaryExpression(expression)) return isRequireCall(expression, /*checkArgumentIsStringLiteralLike*/ true);
diff --git a/tests/cases/fourslash/refactorConvertToEs6Module_unexported_uninitialized_var.ts b/tests/cases/fourslash/refactorConvertToEs6Module_unexported_uninitialized_var.ts
new file mode 100644
index 00000000000..e9cbaafee58
--- /dev/null
+++ b/tests/cases/fourslash/refactorConvertToEs6Module_unexported_uninitialized_var.ts
@@ -0,0 +1,24 @@
+/// <reference path='fourslash.ts' />
+
+// @allowJs: true
+// @target: esnext
+
+// @Filename: /a.js
+////var privateUnrelated;
+////[|exports.f|] = function() {};
+////privateUnrelated = 1;
+////console.log(privateUnrelated);
+
+verify.getSuggestionDiagnostics([{
+    message: "File is a CommonJS module; it may be converted to an ES6 module.",
+    code: 80001,
+}]);
+
+verify.codeFix({
+    description: "Convert to ES6 module",
+    newFileContent:
+`var privateUnrelated;
+export function f() {}
+privateUnrelated = 1;
+console.log(privateUnrelated);`,
+});