feat: replace null with undefined

This is prep for enabling unicorn/no-null, but it's also good practice
and resulted in nicer code.

BREAKING CHANGE: All internal usages of `null` have been replaced with
`undefined`. This includes mapping `null` to `undefined` in Reddit's API
responses. If you were checking any values for existence with `=== null`
you should replace that check with `=== undefined` (or `== null` or
`== undefined`).

src/client.ts

@@ -9,6 +9,7 @@ import {
 } from "./controls";
 import { AnonGateway } from "./gateway/anon";
 import { ClientAuth, OauthGateway } from "./gateway/oauth";
+import { Maybe } from "./helper/types";
 
 /**
  * Options for instantiating a Client
@@ -226,12 +227,12 @@ export default class Client {
   /**
    * Get the refresh token for the current session, if there is one.
    *
-   * @returns The refresh token, or `null` if no token exists.
+   * @returns The refresh token, or `undefined` if no token exists.
    */
-  getRefreshToken(): string | null {
+  getRefreshToken(): Maybe<string> {
     if (this.gateway instanceof OauthGateway) {
       return this.gateway.getRefreshToken();
     }
-    return null;
+    return undefined;
   }
 }

src/controls/comment.ts

@@ -3,7 +3,7 @@ import type { RedditObject } from "../helper/types";
 import type { ListingObject } from "../listings/listing";
 import type { CommentData } from "../objects/comment";
 
-import { assertKind, camelCaseKeys } from "../helper/util";
+import { assertKind, fromRedditData } from "../helper/util";
 import CommentListing from "../listings/comment";
 import { fakeMoreListing } from "../listings/util";
 import Comment from "../objects/comment";
@@ -77,7 +77,7 @@ export default class CommentControls extends VoteableControls {
     const rDat = raw.data;
     const postId = rDat.link_id.slice(3);
     rDat.replies = this.listingifyReplies(rDat.replies, rDat.name, postId);
-    const data: CommentData = camelCaseKeys(rDat);
+    const data: CommentData = fromRedditData(rDat);
     return new Comment(this, data);
   }
 

src/controls/post.ts

@@ -2,6 +2,7 @@ import type Client from "../client";
 import type { Query } from "../gateway/types";
 import type {
   Data,
+  Maybe,
   RedditObject,
   SearchSort,
   SearchSyntax,
@@ -10,7 +11,7 @@ import type {
 import type { ListingObject, RedditListing } from "../listings/listing";
 import type { PostData } from "../objects/post";
 
-import { assertKind, camelCaseKeys } from "../helper/util";
+import { assertKind, fromRedditData } from "../helper/util";
 import CommentListing from "../listings/comment";
 import Listing from "../listings/listing";
 import PostListing from "../listings/post";
@@ -20,7 +21,7 @@ import { LinkPostOptions } from "./subreddit";
 import VoteableControls from "./voteable";
 
 function isRemoved(dat: Data) {
-  if (dat.removed != null) return dat.removed;
+  if (dat.removed != undefined) return dat.removed;
   return !!dat.removal_reason || !!dat.removed_by || !!dat.removed_by_category;
 }
 
@@ -65,14 +66,14 @@ export default class PostControls extends VoteableControls {
    * @param sort The way to sort the search results.
    * @param syntax The search syntax to use.
    * @param restrictSr Whether or not to restrict the search to the given
-   * subreddit. If this is `false` or if `subreddit` is `null` this will search
+   * subreddit. If this is `false` or if `subreddit` is falsy this will search
    * all of Reddit.
    *
    * @returns A listing of posts.
    */
   search(
     query: string,
-    subreddit: string | null,
+    subreddit: Maybe<string>,
     time: TimeRange = "all",
     sort: SearchSort = "new",
     syntax: SearchSyntax = "plain",
@@ -83,7 +84,7 @@ export default class PostControls extends VoteableControls {
       q: query,
       sort,
       syntax,
-      restrict_sr: restrictSr && subreddit != null,
+      restrict_sr: restrictSr && !!subreddit,
     };
 
     if (subreddit) opts.subreddit = subreddit;
@@ -311,7 +312,7 @@ export default class PostControls extends VoteableControls {
 
     rDat.removed = isRemoved(rDat);
 
-    const data: PostData = camelCaseKeys(rDat);
+    const data: PostData = fromRedditData(rDat);
 
     return new Post(this, data);
   }

src/controls/subreddit.ts

@@ -13,7 +13,7 @@ import type { Comment, Post } from "../objects";
 import type { SubredditData } from "../objects/subreddit";
 import type { SplitRawPost } from "./post";
 
-import { assertKind, camelCaseKeys } from "../helper/util";
+import { assertKind, fromRedditData } from "../helper/util";
 import CommentListing from "../listings/comment";
 import PostListing from "../listings/post";
 import PostOrCommentListing from "../listings/postOrComment";
@@ -196,10 +196,10 @@ export default class SubredditControls extends BaseControls {
     options: BanOptions = {}
   ): Promise<void> {
     const opts: Query = {};
-    if (options.duration != null) opts.duration = "" + options.duration;
-    if (options.message != null) opts.ban_message = options.message;
-    if (options.note != null) opts.note = options.note;
-    if (options.reason != null) opts.ban_reason = options.reason;
+    if (options.duration != undefined) opts.duration = "" + options.duration;
+    if (options.message != undefined) opts.ban_message = options.message;
+    if (options.note != undefined) opts.note = options.note;
+    if (options.reason != undefined) opts.ban_reason = options.reason;
 
     await this.friend(sr, name, "banned", opts);
   }
@@ -649,11 +649,11 @@ export default class SubredditControls extends BaseControls {
       spoiler: opts.spoiler,
     };
 
-    if (opts.text != null) req.text = opts.text;
-    if (opts.url != null) req.url = opts.url;
-    if (opts.crosspostFullname != null)
+    if (opts.text != undefined) req.text = opts.text;
+    if (opts.url != undefined) req.url = opts.url;
+    if (opts.crosspostFullname != undefined)
       req.crosspost_fullname = opts.crosspostFullname;
-    if (opts.captcha != null) {
+    if (opts.captcha != undefined) {
       req.captcha = opts.captcha.response;
       req.iden = opts.captcha.iden;
     }
@@ -699,7 +699,7 @@ export default class SubredditControls extends BaseControls {
     rDat.sidebar_html = rDat.description_html;
     rDat.description = rDat.public_description;
     rDat.description_html = rDat.public_description_html;
-    const data: SubredditData = camelCaseKeys(rDat);
+    const data: SubredditData = fromRedditData(rDat);
     return new Subreddit(this, data);
   }
 }

src/controls/user.ts

@@ -9,7 +9,7 @@ import type {
 import type Listing from "../listings/listing";
 import type { MyUserData, OtherUserData, UserData } from "../objects/user";
 
-import { assertKind, camelCaseKeys } from "../helper/util";
+import { assertKind, fromRedditData } from "../helper/util";
 import CommentListing from "../listings/comment";
 import PostListing from "../listings/post";
 import { fakeListingAfter } from "../listings/util";
@@ -102,7 +102,7 @@ export default class UserControls extends BaseControls {
     assertKind("t2", raw);
 
     const rDat = raw.data;
-    const data: UserData = camelCaseKeys(rDat);
+    const data: UserData = fromRedditData(rDat);
 
     if ("coins" in rDat) {
       return new MyUser(this, data as MyUserData);

src/gateway/__tests__/unit/oauth.test.ts

@@ -11,23 +11,22 @@ const fcUsernameAuth = () =>
 const fcTokenAuth = () => fc.record({ refreshToken: fc.string() });
 const fcClientAuth = () => fc.oneof(fcUsernameAuth(), fcTokenAuth());
 
-function fcToken(refresh?: boolean): fc.Arbitrary<Token> {
+function fcToken(withRefresh?: boolean): fc.Arbitrary<Token> {
   const access = fc.string();
   const expiration = fc.integer().map(i => i + Date.now());
+  const refresh = fc.string({ minLength: 1 });
 
-  if (refresh == null) {
+  if (withRefresh === true) {
+    return fc.record({ access, expiration, refresh });
+  } else if (withRefresh === false) {
+    return fc.record({ access, expiration });
+  } else {
     // No preference given, randomize whether or not there is a refresh token.
     return fc.record(
-      { access, expiration, refresh: fc.string() },
+      { access, expiration, refresh },
       { requiredKeys: ["access", "expiration"] }
     );
   }
-
-  if (refresh) {
-    return fc.record({ access, expiration, refresh: fc.string() });
-  } else {
-    return fc.record({ access, expiration });
-  }
 }
 
 function fcTokenResponse(): fc.Arbitrary<TokenResponse> {
@@ -41,10 +40,10 @@ function fcTokenResponse(): fc.Arbitrary<TokenResponse> {
 
 // Test class to make protected methods public.
 class PublicOauthGateway extends OauthGateway {
-  public getToken(): Token | null {
+  public getToken(): Maybe<Token> {
     return this.token;
   }
-  public setToken(token: Token | null) {
+  public setToken(token: Maybe<Token>) {
     this.token = token;
   }
 
@@ -192,7 +191,7 @@ describe("OauthGateway", () => {
   });
 
   describe.each([
-    ["not authenticated", null],
+    ["not authenticated", undefined],
     [
       "access has expired",
       { access: "accessTkn", expiration: Date.now() - 9000 },

src/gateway/gateway.ts

@@ -114,7 +114,7 @@ export abstract class Gateway {
 
   protected handleError(msg: string, desc?: string): never {
     let errMsg = `Reddit returned an error: ${msg}`;
-    if (desc != null) errMsg += `: ${desc}`;
+    if (desc) errMsg += `: ${desc}`;
     throw new Error(errMsg);
   }
 

src/gateway/oauth.ts

@@ -2,7 +2,7 @@ import type { Data, Maybe } from "../helper/types";
 import type { Credentials } from "./creds";
 import type { BearerAuth } from "./types";
 
-import { camelCaseKeys } from "../helper/util";
+import { fromRedditData } from "../helper/util";
 import { CredsGateway } from "./creds";
 import { Gateway } from "./gateway";
 
@@ -74,7 +74,7 @@ type Grant =
 export class OauthGateway extends Gateway {
   protected initialAuth: Maybe<ClientAuth>;
   protected creds: Credentials;
-  protected token: Token | null;
+  protected token: Maybe<Token>;
 
   /** @internal */
   static async fromAuthCode(
@@ -98,12 +98,11 @@ export class OauthGateway extends Gateway {
     super("https://oauth.reddit.com", userAgent);
     this.initialAuth = auth;
     this.creds = creds;
-    this.token = null;
   }
 
   /** @internal */
-  public getRefreshToken(): string | null {
-    return this.token?.refresh ?? null;
+  public getRefreshToken(): Maybe<string> {
+    return this.token?.refresh;
   }
 
   protected async auth(): Promise<BearerAuth> {
@@ -126,7 +125,7 @@ export class OauthGateway extends Gateway {
 
   protected async updateAccessToken(): Promise<void> {
     let grant: Grant;
-    if (this.token?.refresh != null) {
+    if (this.token?.refresh) {
       grant = {
         grant_type: "refresh_token",
         refresh_token: this.token.refresh,
@@ -151,7 +150,7 @@ export class OauthGateway extends Gateway {
   private async updateTokenFromGrant(grant: Grant) {
     const credGate = new CredsGateway(this.creds, this.userAgent);
     const raw: Data = await credGate.post("api/v1/access_token", grant);
-    const tkns: TokenResponse = camelCaseKeys(raw);
+    const tkns: TokenResponse = fromRedditData(raw);
     this.token = {
       access: tkns.accessToken,
       expiration: Date.now() + tkns.expiresIn * 1000,

src/helper/__tests__/unit/util.test.ts

@@ -1,17 +1,24 @@
 import * as util from "../../util";
 
-describe("camelCaseKeys()", () => {
+describe("fromRedditData()", () => {
   it("should convert keys to camel case", () => {
     const a = { foo_bar: "a", bar_foo: "b" };
     const b = { fooBar: "a", barFoo: "b" };
 
-    expect(util.camelCaseKeys(a)).toStrictEqual(b);
+    expect(util.fromRedditData(a)).toStrictEqual(b);
   });
 
   it("should preserve camel cased keys", () => {
     const a = { fooBar: "a", barFoo: "b" };
     const b = { fooBar: "a", barFoo: "b" };
 
-    expect(util.camelCaseKeys(a)).toStrictEqual(b);
+    expect(util.fromRedditData(a)).toStrictEqual(b);
+  });
+
+  it("should replace null with undefined", () => {
+    const a = { fooBar: null, barFoo: undefined };
+    const b = { fooBar: undefined, barFoo: undefined };
+
+    expect(util.fromRedditData(a)).toStrictEqual(b);
   });
 });

src/helper/util.ts

@@ -4,10 +4,17 @@ import camelCase from "camelcase";
 
 import { InvalidKindError } from "./errors";
 
-export function camelCaseKeys<T>(obj: Data): T {
+/**
+ * Convert a value from a reddit API response to a snoots data structure.
+ *
+ * This performs two steps:
+ * 1. Replace `null` with `undefined`
+ * 2. Convert the key from snake_case to camelCase
+ */
+export function fromRedditData<T>(data: Data): T {
   const out: Data = {};
-  for (const key in obj) {
-    out[camelCase(key)] = obj[key];
+  for (const key in data) {
+    out[camelCase(key)] = data[key] === null ? undefined : data[key];
   }
   return out as T;
 }

src/listings/comment/commentListing.ts

@@ -15,7 +15,7 @@ export default class CommentListing extends Listing<Comment> {
   constructor(l: RedditListing, ctx: ListingContext) {
     let fetcher: Fetcher<Comment> | undefined;
 
-    if (l.after != null) {
+    if (l.after) {
       fetcher = new CommentPager(l.after);
     }
 

src/listings/comment/more.ts

@@ -2,7 +2,7 @@ import type { Data, RedditObject } from "../../helper/types";
 import type Comment from "../../objects/comment";
 import type { Fetcher, ListingContext, RedditMore } from "../listing";
 
-import { emptyRedditListing, wrapChildren } from "./../util";
+import { emptyRedditListing } from "./../util";
 import CommentListing from "./commentListing";
 
 function fixCommentTree(objects: RedditObject[]) {
@@ -15,7 +15,7 @@ function fixCommentTree(objects: RedditObject[]) {
     // Ensure that all the comments have a replies listing.
     if (item.kind === "t1") {
       if (item.data.replies !== "") throw "?????";
-      item.data.replies = { kind: "Listing", data: wrapChildren([]) };
+      item.data.replies = { kind: "Listing", data: { children: [] } };
     }
   }
 
@@ -84,7 +84,7 @@ export default class MoreComments implements Fetcher<Comment> {
         children.push(more);
       }
 
-      return new CommentListing(wrapChildren(children), ctx);
+      return new CommentListing({ children }, ctx);
     }
   }
 }