[Fixes #29] Reworking formData dependency import. (#30)

* Reworking formData dependency import.

* Fixing CI issues.

* Disabling rule for a line instead of the whole project.

package.json

@@ -1,6 +1,6 @@
 {
   "name": "@onfido/api",
-  "version": "1.5.2",
+  "version": "1.5.3",
   "description": "Node.js library for the Onfido API",
   "keywords": [
     "onfido",
@@ -37,23 +37,23 @@
     },
     "globals": {
       "ts-jest": {
-        "tsConfig": "test/tsconfig.json"
+        "tsconfig": "test/tsconfig.json"
       }
     }
   },
   "devDependencies": {
     "@rollup/plugin-json": "^4.1.0",
-    "@types/jest": "^25.1.4",
-    "jest": "^25.2.4",
+    "@types/jest": "^26.0.15",
+    "jest": "^26.6.3",
     "nock": "^11.7.0",
     "prettier": "^1.18.2",
     "rollup": "^1.24.0",
     "rollup-plugin-typescript2": "^0.25.3",
-    "ts-jest": "^25.3.0",
+    "ts-jest": "^26.4.4",
     "tslint": "^5.20.0",
     "tslint-config-prettier": "^1.18.0",
     "tslint-plugin-prettier": "^2.0.1",
-    "typescript": "^3.6.4"
+    "typescript": "^4.0.5"
   },
   "dependencies": {
     "axios": "^0.19.0",

src/formatting.ts

@@ -1,5 +1,9 @@
-import FormData from "form-data";
 import { Readable } from "stream";
+import { IFormData } from "./types/formData";
+
+// Using require because "form-data" exports this object as a default export which breaks integration when esModuleInterop: false
+// tslint:disable-next-line: no-var-requires
+const FormData = require("form-data");
 
 export type SimpleObject = { [key: string]: unknown };
 
@@ -41,7 +45,7 @@ export const convertObjectToCamelCase = (
   responseBody: SimpleObject
 ): SimpleObject => deepMapObjectKeys(responseBody, camelCase);
 
-export const toFormData = (object: SimpleObject): FormData => {
+export const toFormData = (object: SimpleObject): IFormData => {
   return Object.entries(object).reduce((formData, [key, value]) => {
     if (value instanceof Object && "contents" in value) {
       const { contents, ...options } = value as ContentsAndOptions;

src/types/formData.ts

@@ -0,0 +1,33 @@
+// Copied over from form-data.
+import * as http from "http";
+import * as stream from "stream";
+
+export interface IFormData extends stream.Readable {
+  append(key: string, value: any, options?: IAppendOptions | string): void;
+  getHeaders(userHeaders?: IHeaders): IHeaders;
+  submit(
+    params: string | ISubmitOptions,
+    callback?: (error: Error | null, response: http.IncomingMessage) => void
+  ): http.ClientRequest;
+  getBuffer(): Buffer;
+  getBoundary(): string;
+  getLength(callback: (err: Error | null, length: number) => void): void;
+  getLengthSync(): number;
+  hasKnownLength(): boolean;
+}
+
+interface IHeaders {
+  [key: string]: any;
+}
+
+interface IAppendOptions {
+  header?: string | IHeaders;
+  knownLength?: number;
+  filename?: string;
+  filepath?: string;
+  contentType?: string;
+}
+
+interface ISubmitOptions extends http.RequestOptions {
+  protocol?: "https:" | "http:";
+}

test/formatting.test.ts

@@ -30,4 +30,11 @@ describe("toFormData", () => {
   it("omits undefined and null values", () => {
     expect(() => toFormData({ a: null, b: undefined })).not.toThrow();
   });
+
+  it("should return proper FormData object", () => {
+    const formData = toFormData({ a: "A", b: "B" });
+    expect(formData.getBoundary()).toContain("----");
+    expect(formData.getLengthSync()).toEqual(258);
+    expect(formData.hasKnownLength()).toBeTruthy();
+  });
 });