Allow bom markers

app/server/src/configReader.ts

@@ -1,6 +1,19 @@
 import * as fs from "fs";
 import * as path from "path";
 
+export function stripBom(str: string): string {
+    // Catches EFBBBF (UTF-8 BOM) because the buffer-to-string
+    // conversion translates it to FEFF (UTF-16 BOM).
+    if (str.charCodeAt(0) === 0xFEFF) {
+        return str.slice(1);
+    }
+    return str;
+}
+
+export function readFile(filename: string): string {
+    return stripBom(fs.readFileSync(filename, { encoding: "utf-8" }));
+}
+
 export class ConfigReader {
     rootDir: string;
 
@@ -15,7 +28,7 @@ export class ConfigReader {
         const fullPath = [this.rootDir, ...filePath];
         const filename = path.join(...fullPath);
         if (fs.existsSync(filename)) {
-            const configText = fs.readFileSync(filename, { encoding: "utf-8" });
+            const configText = readFile(filename);
             return { ...JSON.parse(configText), ...this.overrides };
         }
         return null;

app/server/tests/configReader.test.ts

@@ -3,7 +3,7 @@ import { ConfigReader } from "../src/configReader";
 
 describe("configReader", () => {
     beforeEach(() => {
-        jest.resetAllMocks();
+        jest.restoreAllMocks();
     });
 
     it("returns null when config not found", () => {
@@ -31,4 +31,9 @@ describe("configReader", () => {
         expect(mockReadFileSync.mock.calls[0][0]).toBe("root/test.config");
         expect(mockReadFileSync.mock.calls[0][1]).toStrictEqual({ encoding: "utf-8" });
     });
+
+    it("copes with BOM markers", () => {
+        const res: any = new ConfigReader(__dirname).readConfigFile("examples/bom.json");
+        expect((res as any).title).toBe("Ebola Project");
+    });
 });

app/server/tests/examples/bom.json

@@ -0,0 +1,6 @@
+{
+  "appType": "fit",
+  "title": "Ebola Project",
+  "fitProp": "",
+  "readOnlyCode": false
+}