fix(form-data): fixed formData type check

src/file/generateFileUploadForm.ts

@@ -1,5 +1,6 @@
 import * as NodeFormData from 'form-data'
 import { convertToCSV } from '../utils/convertToCsv'
+import { isNode } from '../utils'
 
 /**
  * One of the approaches SASjs takes to send tables-formatted JSON (see README)
@@ -26,12 +27,14 @@ export const generateFileUploadForm = (
       )
     }
 
-    if (formData instanceof NodeFormData) {
-      formData.append(name, csv, {
+    if (isNode()) {
+      // environment is Node and formData is instance of NodeFormData
+      ;(formData as NodeFormData).append(name, csv, {
         filename: `${name}.csv`,
         contentType: 'application/csv'
       })
-    } else if (formData instanceof FormData) {
+    } else {
+      // environment is Browser and formData is instance of FormData
       const file = new Blob([csv], {
         type: 'application/csv'
       })

src/file/spec/generateFileUploadForm.spec.ts

@@ -1,6 +1,7 @@
 import { generateFileUploadForm } from '../generateFileUploadForm'
-import * as NodeFormData from 'form-data'
 import { convertToCSV } from '../../utils/convertToCsv'
+import * as NodeFormData from 'form-data'
+import * as isNodeModule from '../../utils/isNode'
 
 describe('generateFileUploadForm', () => {
   beforeAll(() => {
@@ -14,6 +15,10 @@ describe('generateFileUploadForm', () => {
   })
 
   describe('browser', () => {
+    afterAll(() => {
+      jest.restoreAllMocks()
+    })
+
     it('should generate file upload form from data', () => {
       const formData = new FormData()
       const testTable = 'sometable'
@@ -33,6 +38,7 @@ describe('generateFileUploadForm', () => {
       )[0]
 
       jest.spyOn(formData, 'append').mockImplementation(() => {})
+      jest.spyOn(isNodeModule, 'isNode').mockImplementation(() => false)
 
       generateFileUploadForm(formData, testTableWithNullVars)