add test for exportToFile

src/fileUtils.js

@@ -0,0 +1,17 @@
+export default {
+  exportToFile (str, fileName, type = 'octet/stream') {
+    // Create downloader
+    const downloader = document.createElement('a')
+    const blob = new Blob([str], { type })
+    const url = URL.createObjectURL(blob)
+    downloader.href = url
+    downloader.download = fileName
+
+    // Trigger click
+    downloader.click()
+
+    // Clean up
+    URL.revokeObjectURL(url)
+    downloader.remove()
+  }
+}