From 249c2cbaf754164c3f6d0e7a03c53002575b4060 Mon Sep 17 00:00:00 2001
From: Charles Pierce <charlespierce@users.noreply.github.com>
Date: Tue, 10 Oct 2017 15:39:59 -0700
Subject: [PATCH] Maintain Export Modifier when Refactoring to ES6 Class #18435
 (#19070)

---
 .../refactors/convertFunctionToEs6Class.ts    | 10 ++++++++--
 ...nvertFunctionToEs6Class_exportModifier1.ts | 19 +++++++++++++++++++
 ...nvertFunctionToEs6Class_exportModifier2.ts | 19 +++++++++++++++++++
 3 files changed, 46 insertions(+), 2 deletions(-)
 create mode 100644 tests/cases/fourslash/convertFunctionToEs6Class_exportModifier1.ts
 create mode 100644 tests/cases/fourslash/convertFunctionToEs6Class_exportModifier2.ts

diff --git a/src/services/refactors/convertFunctionToEs6Class.ts b/src/services/refactors/convertFunctionToEs6Class.ts
index e4cd1a42083..110f64d1220 100644
--- a/src/services/refactors/convertFunctionToEs6Class.ts
+++ b/src/services/refactors/convertFunctionToEs6Class.ts
@@ -243,7 +243,8 @@ namespace ts.refactor.convertFunctionToES6Class {
                 memberElements.unshift(createConstructor(/*decorators*/ undefined, /*modifiers*/ undefined, initializer.parameters, initializer.body));
             }
 
-            const cls = createClassDeclaration(/*decorators*/ undefined, /*modifiers*/ undefined, node.name,
+            const modifiers = getExportModifierFromSource(precedingNode);
+            const cls = createClassDeclaration(/*decorators*/ undefined, modifiers, node.name,
                 /*typeParameters*/ undefined, /*heritageClauses*/ undefined, memberElements);
             // Don't call copyComments here because we'll already leave them in place
             return cls;
@@ -255,10 +256,15 @@ namespace ts.refactor.convertFunctionToES6Class {
                 memberElements.unshift(createConstructor(/*decorators*/ undefined, /*modifiers*/ undefined, node.parameters, node.body));
             }
 
-            const cls = createClassDeclaration(/*decorators*/ undefined, /*modifiers*/ undefined, node.name,
+            const modifiers = getExportModifierFromSource(node);
+            const cls = createClassDeclaration(/*decorators*/ undefined, modifiers, node.name,
                 /*typeParameters*/ undefined, /*heritageClauses*/ undefined, memberElements);
             // Don't call copyComments here because we'll already leave them in place
             return cls;
         }
+
+        function getExportModifierFromSource(source: Node) {
+            return filter(source.modifiers, modifier => modifier.kind === SyntaxKind.ExportKeyword);
+        }
     }
 }
\ No newline at end of file
diff --git a/tests/cases/fourslash/convertFunctionToEs6Class_exportModifier1.ts b/tests/cases/fourslash/convertFunctionToEs6Class_exportModifier1.ts
new file mode 100644
index 00000000000..940a68a05b6
--- /dev/null
+++ b/tests/cases/fourslash/convertFunctionToEs6Class_exportModifier1.ts
@@ -0,0 +1,19 @@
+/// <reference path='fourslash.ts' />
+
+// @allowNonTsExtensions: true
+// @Filename: test123.js
+////export function /**/MyClass() {
+////}
+////MyClass.prototype.foo = function() {
+////}
+
+verify.applicableRefactorAvailableAtMarker("");
+verify.fileAfterApplyingRefactorAtMarker("",
+`export class MyClass {
+    constructor() {
+    }
+    foo() {
+    }
+}
+`,
+'Convert to ES2015 class', 'convert');
diff --git a/tests/cases/fourslash/convertFunctionToEs6Class_exportModifier2.ts b/tests/cases/fourslash/convertFunctionToEs6Class_exportModifier2.ts
new file mode 100644
index 00000000000..fb1276d4f03
--- /dev/null
+++ b/tests/cases/fourslash/convertFunctionToEs6Class_exportModifier2.ts
@@ -0,0 +1,19 @@
+/// <reference path='fourslash.ts' />
+
+// @allowNonTsExtensions: true
+// @Filename: test123.js
+////export const /**/foo = function() {
+////};
+////foo.prototype.instanceMethod = function() {
+////};
+
+verify.applicableRefactorAvailableAtMarker("");
+verify.fileAfterApplyingRefactorAtMarker("",
+`export class foo {
+    constructor() {
+    }
+    instanceMethod() {
+    }
+}
+`,
+'Convert to ES2015 class', 'convert');