fix: #308 - Should not insert before the BOM.

src/constants.ts

@@ -0,0 +1,3 @@
+export const Chars = {
+    BOM: "\uFEFF"
+};

src/manipulation/helpers/getInsertPosFromIndex.ts

@@ -1,5 +1,6 @@
 import {ts, SyntaxKind} from "../../typescript";
 import {Node} from "../../compiler";
+import {Chars} from "../../constants";
 import {TypeGuards} from "../../utils";
 import {getPosAtStartOfLineOrNonWhitespace} from "../textSeek";
 
@@ -9,7 +10,7 @@ import {getPosAtStartOfLineOrNonWhitespace} from "../textSeek";
 export function getInsertPosFromIndex(index: number, parent: Node, children: Node[]) {
     if (index === 0) {
         if (TypeGuards.isSourceFile(parent))
-            return 0;
+            return parent.getFullText()[0] === Chars.BOM ? 1 : 0;
         else if (TypeGuards.isCaseClause(parent) || TypeGuards.isDefaultClause(parent)) {
             const colonToken = parent.getFirstChildByKindOrThrow(SyntaxKind.ColonToken);
             return colonToken.getEnd();

src/manipulation/manipulations/insertion.ts

@@ -1,5 +1,6 @@
 import CodeBlockWriter from "code-block-writer";
 import { ts, SyntaxKind } from "../../typescript";
+import { Chars } from "../../constants";
 import {Node, SourceFile} from "../../compiler";
 import {StringUtils, TypeGuards} from "../../utils";
 import {InsertionTextManipulator} from "../textManipulators";
@@ -153,7 +154,7 @@ export function insertIntoBracesOrSourceFile<TStructure = {}>(opts: InsertIntoBr
         opts.write(writer, {
             previousMember: getChild(children[index - 1]),
             nextMember: getChild(children[index]),
-            isStartOfFile: insertPos === 0
+            isStartOfFile: insertPos === 0 || insertPos === 1 && fullText[0] === Chars.BOM
         });
         return writer.toString();
 

src/tests/compiler/file/sourceFileTests.ts

@@ -1,5 +1,6 @@
 import {expect} from "chai";
 import * as errors from "../../../errors";
+import { Chars } from "../../../constants";
 import {ts, LanguageVariant, ScriptTarget, NewLineKind, CompilerOptions, ModuleResolutionKind} from "../../../typescript";
 import {SourceFile, ImportDeclaration, ExportDeclaration, ExportAssignment, EmitResult, FormatCodeSettings, QuoteKind,
     FileSystemRefreshResult} from "../../../compiler";
@@ -392,7 +393,7 @@ describe(nameof(SourceFile), () => {
                 project.manipulationSettings.set({ quoteKind: QuoteKind.Single });
             const result = sourceFile.insertImportDeclarations(index, structures);
             expect(result.length).to.equal(structures.length);
-            expect(sourceFile.getText()).to.equal(expectedCode);
+            expect(sourceFile.getFullText()).to.equal(expectedCode);
         }
 
         it("should insert the different kinds of imports", () => {
@@ -421,6 +422,10 @@ describe(nameof(SourceFile), () => {
             }).to.throw();
         });
 
+        it("should insert an import after a utf-8 bom", () => {
+            doTest(Chars.BOM, 0, [{ moduleSpecifier: "./test" }], `${Chars.BOM}import "./test";\n`);
+        });
+
         it("should insert at the beginning and use single quotes when specified", () => {
             doTest(`export class Class {}\n`, 0, [{ moduleSpecifier: "./test" }], `import './test';\n\nexport class Class {}\n`, true);
         });

src/tests/compiler/statement/statementedNodeTests.ts

@@ -1,4 +1,5 @@
 import {expect} from "chai";
+import { Chars } from "../../../constants";
 import {ts, SyntaxKind} from "../../../typescript";
 import {CaseClause, DefaultClause, StatementedNode, SourceFile, FunctionDeclaration, NamespaceDeclaration, Node} from "../../../compiler";
 import {StatementedNodeStructure} from "../../../structures";
@@ -111,6 +112,10 @@ describe(nameof(StatementedNode), () => {
                 "newText;\nsecondText;\n");
         });
 
+        it("should insert statements after a utf-8 bom", () => {
+            doSourceFileTest(Chars.BOM, 0, "newText;", 1, Chars.BOM + "newText;\n");
+        });
+
         it("should allow inserting nothing", () => {
             doSourceFileTest("", 0, "", 0, "");
         });

src/utils/FileUtils.ts

@@ -3,6 +3,7 @@ import globParent = require("glob-parent");
 import isNegatedGlob = require("is-negated-glob");
 import * as toAbsoluteGlob from "@dsherret/to-absolute-glob";
 import {FileSystemHost, FileSystemWrapper} from "../fileSystem";
+import { Chars } from "../constants";
 import {StringUtils} from "./StringUtils";
 import {ArrayUtils} from "./ArrayUtils";
 
@@ -240,10 +241,9 @@ export class FileUtils {
      * @param text - Text.
      */
     static getTextWithByteOrderMark(text: string) {
-        const bom = "\ufeff";
-        if (text[0] === bom)
+        if (text[0] === Chars.BOM)
             return text;
-        return bom + text;
+        return Chars.BOM + text;
     }
 
     /**