moveToNewFile: Reuse code from importFixes for inserting import (#24957)

* moveToNewFile: Reuse code from importFixes for inserting import

* Fix test failures

* Update API baselines (#24966)

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 = makeStringLiteral(moduleSpecifierWithoutQuotes, getQuotePreference(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

@@ -121,7 +121,7 @@ namespace ts.refactor {
         const quotePreference = getQuotePreference(oldFile, preferences);
         const importsFromNewFile = createOldFileImportsFromNewFile(usage.oldFileImportsFromNewFile, newModuleName, useEs6ModuleSyntax, quotePreference);
         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

@@ -1379,6 +1379,17 @@ namespace ts {
         return textSpanContainsPosition(span, node.getStart(file)) &&
             node.getEnd() <= textSpanEnd(span);
     }
+
+    /* @internal */
+    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/baselines/reference/api/tsserverlibrary.d.ts

@@ -10610,6 +10610,7 @@ declare namespace ts {
         some(pred: (node: Node) => boolean): boolean;
     }
     function getParentNodeInSpan(node: Node | undefined, file: SourceFile, span: TextSpan): Node | undefined;
+    function insertImport(changes: textChanges.ChangeTracker, sourceFile: SourceFile, importDecl: Statement): void;
 }
 declare namespace ts {
     function isFirstDeclarationOfSymbolParameter(symbol: Symbol): boolean;

tests/baselines/reference/api/typescript.d.ts

@@ -10790,6 +10790,7 @@ declare namespace ts {
         some(pred: (node: Node) => boolean): boolean;
     }
     function getParentNodeInSpan(node: Node | undefined, file: SourceFile, span: TextSpan): Node | undefined;
+    function insertImport(changes: textChanges.ChangeTracker, sourceFile: SourceFile, importDecl: Statement): void;
 }
 declare namespace ts {
     function isFirstDeclarationOfSymbolParameter(symbol: Symbol): boolean;

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;`,
 

tests/cases/fourslash/moveToNewFile_inferQuoteStyle.ts

@@ -9,9 +9,8 @@
 verify.moveToNewFile({
     newFileContents: {
         "/a.ts":
-`import { x } from './x';
-
-import 'unrelated';
+`import 'unrelated';
+import { x } from './x';
 
 x;`,