moveToNewFile: Format the new file (microsoft#24379)

Author: Andy

src/services/textChanges.ts

@@ -687,7 +687,7 @@ namespace ts.textChanges {
             this.finishTrailingCommaAfterDeletingNodesInList();
             const changes = changesToText.getTextChangesFromChanges(this.changes, this.newLineCharacter, this.formatContext, validate);
             for (const { oldFile, fileName, statements } of this.newFiles) {
-                changes.push(changesToText.newFileChanges(oldFile, fileName, statements, this.newLineCharacter));
+                changes.push(changesToText.newFileChanges(oldFile, fileName, statements, this.newLineCharacter, this.formatContext));
             }
             return changes;
         }
@@ -726,8 +726,12 @@ namespace ts.textChanges {
             });
         }
 
-        export function newFileChanges(oldFile: SourceFile, fileName: string, statements: ReadonlyArray<Statement>, newLineCharacter: string): FileTextChanges {
-            const text = statements.map(s => getNonformattedText(s, oldFile, newLineCharacter).text).join(newLineCharacter);
+        export function newFileChanges(oldFile: SourceFile, fileName: string, statements: ReadonlyArray<Statement>, newLineCharacter: string, formatContext: formatting.FormatContext): FileTextChanges {
+            // TODO: this emits the file, parses it back, then formats it that -- may be a less roundabout way to do this
+            const nonFormattedText = statements.map(s => getNonformattedText(s, oldFile, newLineCharacter).text).join(newLineCharacter);
+            const sourceFile = createSourceFile(fileName, nonFormattedText, ScriptTarget.ESNext);
+            const changes = formatting.formatDocument(sourceFile, formatContext);
+            const text = applyChanges(nonFormattedText, changes);
             return { fileName, textChanges: [createTextChange(createTextSpan(0, 0), text)], isNewFile: true };
         }
 

tests/cases/fourslash/fourslash.ts

@@ -69,9 +69,7 @@ declare module ts {
         writeByteOrderMark: boolean;
         text: string;
     }
-}
 
-declare namespace ts {
     function flatMap<T, U>(array: ReadonlyArray<T>, mapfn: (x: T, i: number) => U | ReadonlyArray<U> | undefined): U[];
 }
 

tests/cases/fourslash/moveToNewFile_format.ts

@@ -0,0 +1,21 @@
+/// <reference path='fourslash.ts' />
+
+// @Filename: /a.ts
+////[|function f() {
+////	const x = 0;
+////}|]
+
+var copy = format.copyFormatOptions();
+copy.ConvertTabsToSpaces = false;
+format.setFormatOptions(copy);
+
+verify.moveToNewFile({
+    newFileContents: {
+        "/a.ts":
+``,
+        "/f.ts":
+`function f() {
+	const x = 0;
+}`,
+    },
+});