test: add unit test for resvg.ts

src/converters/potrace.ts

@@ -28,7 +28,7 @@ export function convert(
   convertTo: string,
   targetPath: string,
   options?: unknown,
-  execFile: ExecFileFn = execFileOriginal,
+  execFile: ExecFileFn = execFileOriginal, // to make it mockable
 ): Promise<string> {
   return new Promise((resolve, reject) => {
     execFile("potrace", [filePath, "-o", targetPath, "-b", convertTo], (error, stdout, stderr) => {