moveToNewFile: Reuse code from importFixes for inserting import

Author: Andy Hanson

src/services/codefixes/importFixes.ts

@@ -194,7 +194,6 @@ namespace ts.codefix {
 
     function getCodeActionForNewImport(context: SymbolContext & { preferences: UserPreferences }, { moduleSpecifier, importKind }: NewImportInfo): CodeFixAction {
         const { sourceFile, symbolName, preferences } = context;
-        const lastImportDeclaration = findLast(sourceFile.statements, isAnyImportSyntax);
 
         const moduleSpecifierWithoutQuotes = stripQuotes(moduleSpecifier);
         const quotedModuleSpecifier = createLiteral(moduleSpecifierWithoutQuotes, shouldUseSingleQuote(sourceFile, preferences));
@@ -210,14 +209,7 @@ namespace ts.codefix {
                 createIdentifier(symbolName),
                 createExternalModuleReference(quotedModuleSpecifier));
 
-        const changes = ChangeTracker.with(context, changeTracker => {
-            if (lastImportDeclaration) {
-                changeTracker.insertNodeAfter(sourceFile, lastImportDeclaration, importDecl);
-            }
-            else {
-                changeTracker.insertNodeAtTopOfFile(sourceFile, importDecl, /*blankLineBetween*/ true);
-            }
-        });
+        const changes = ChangeTracker.with(context, t => insertImport(t, sourceFile, importDecl));
 
         // if this file doesn't have any import statements, insert an import statement and then insert a new line
         // between the only import statement and user code. Otherwise just insert the statement because chances

src/services/refactors/moveToNewFile.ts

@@ -120,7 +120,7 @@ namespace ts.refactor {
         const useEs6ModuleSyntax = !!oldFile.externalModuleIndicator;
         const importsFromNewFile = createOldFileImportsFromNewFile(usage.oldFileImportsFromNewFile, newModuleName, useEs6ModuleSyntax, preferences);
         if (importsFromNewFile) {
-            changes.insertNodeBefore(oldFile, oldFile.statements[0], importsFromNewFile, /*blankLineBetween*/ true);
+            insertImport(changes, oldFile, importsFromNewFile);
         }
 
         deleteUnusedOldImports(oldFile, toMove.all, changes, usage.unusedImportsFromOldFile, checker);

src/services/utilities.ts

@@ -1363,6 +1363,16 @@ namespace ts {
         return textSpanContainsPosition(span, node.getStart(file)) &&
             node.getEnd() <= textSpanEnd(span);
     }
+
+    export function insertImport(changes: textChanges.ChangeTracker, sourceFile: SourceFile, importDecl: Statement): void {
+        const lastImportDeclaration = findLast(sourceFile.statements, isAnyImportSyntax);
+        if (lastImportDeclaration) {
+            changes.insertNodeAfter(sourceFile, lastImportDeclaration, importDecl);
+        }
+        else {
+            changes.insertNodeAtTopOfFile(sourceFile, importDecl, /*blankLineBetween*/ true);
+        }
+    }
 }
 
 // Display-part writer helpers

tests/cases/fourslash/moveToNewFile.ts

@@ -1,6 +1,8 @@
 /// <reference path='fourslash.ts' />
 
 // @Filename: /a.ts
+////// header comment
+////
 ////import './foo';
 ////import { a, b, alreadyUnused } from './other';
 ////const p = 0;
@@ -10,10 +12,11 @@
 verify.moveToNewFile({
     newFileContents: {
         "/a.ts":
-`import { y } from './y';
+`// header comment
 
 import './foo';
 import { a, alreadyUnused } from './other';
+import { y } from './y';
 export const p = 0;
 a; y;`,