feat: prune existing badges out of README.md during hydration (#637)

## PR Checklist

- [x] Addresses an existing open issue: fixes #502
- [x] That issue was marked as [`status: accepting
prs`](https://github.com/JoshuaKGoldberg/template-typescript-node-package/issues?q=is%3Aopen+is%3Aissue+label%3A%22status%3A+accepting+prs%22)
- [x] Steps in
[CONTRIBUTING.md](https://github.com/JoshuaKGoldberg/template-typescript-node-package/blob/main/.github/CONTRIBUTING.md)
were taken

## Overview

Adds some regexp fanciness to remove existing badges. They detect badges
in the two formats referenced in the issue. Also adds a bit of snapshot
unit testing.

Author: JoshuaKGoldberg

src/hydrate/steps/writeReadme.test.ts

@@ -0,0 +1,96 @@
+import { describe, expect, it, vi } from "vitest";
+
+import { writeReadme } from "./writeReadme.js";
+
+const mockWriteFile = vi.fn();
+
+vi.mock("node:fs/promises", () => ({
+	get default() {
+		return {
+			get writeFile() {
+				return mockWriteFile;
+			},
+		};
+	},
+}));
+
+const mockReadFileSafe = vi.fn();
+
+vi.mock("../readFileSafe.js", () => ({
+	get readFileSafe() {
+		return mockReadFileSafe;
+	},
+}));
+
+const stubValues = {
+	author: "Test Author",
+	description: "Test description.",
+	email: "[email protected]",
+	funding: undefined,
+	owner: "TestOwner",
+	releases: undefined,
+	repository: "test-repository",
+	skipApi: false,
+	skipRemoval: false,
+	skipRestore: false,
+	skipUninstalls: false,
+	title: "Test Title",
+	unitTests: undefined,
+};
+
+describe("writeReadme", () => {
+	it("writes a new file when README.md does not yet exist", async () => {
+		mockReadFileSafe.mockResolvedValue(undefined);
+
+		await writeReadme(stubValues);
+
+		expect(mockWriteFile.mock.calls).toMatchInlineSnapshot(`
+			[
+			  [
+			    "README.md",
+			    "<h1 align=\\"center\\">Test Title</h1>
+
+			<p align=\\"center\\">Test description.</p>
+
+			<p align=\\"center\\">
+				<a href=\\"#contributors\\" target=\\"_blank\\">
+			<!-- prettier-ignore-start -->
+			<!-- ALL-CONTRIBUTORS-BADGE:START - Do not remove or modify this section -->
+			<img alt=\\"All Contributors: 17\\" src=\\"https://img.shields.io/badge/all_contributors-17-21bb42.svg\\" />
+			<!-- ALL-CONTRIBUTORS-BADGE:END -->
+			<!-- prettier-ignore-end -->
+				</a>
+				<a href=\\"https://codecov.io/gh/TestOwner/test-repository\\" target=\\"_blank\\">
+				</a>
+				<a href=\\"https://github.com/TestOwner/test-repository/blob/main/.github/CODE_OF_CONDUCT.md\\" target=\\"_blank\\">
+					<img alt=\\"Contributor Covenant\\" src=\\"https://img.shields.io/badge/code_of_conduct-enforced-21bb42\\" />
+				</a>
+				<a href=\\"https://github.com/TestOwner/test-repository/blob/main/LICENSE.md\\" target=\\"_blank\\">
+					<img alt=\\"License: MIT\\" src=\\"https://img.shields.io/github/license/TestOwner/test-repository?color=21bb42\\">
+				</a>
+				<img alt=\\"Style: Prettier\\" src=\\"https://img.shields.io/badge/style-prettier-21bb42.svg\\" />
+				<img alt=\\"TypeScript: Strict\\" src=\\"https://img.shields.io/badge/typescript-strict-21bb42.svg\\" />
+			</p>
+
+
+			## Contributors
+
+			<!-- spellchecker: disable -->
+			<!-- ALL-CONTRIBUTORS-LIST:START - Do not remove or modify this section -->
+			<!-- prettier-ignore-start -->
+			<!-- markdownlint-disable -->
+			<table>
+			<!-- (this will be filled in by all-contributors) -->
+			</table>
+
+			<!-- markdownlint-restore -->
+			<!-- prettier-ignore-end -->
+
+			<!-- ALL-CONTRIBUTORS-LIST:END -->
+			<!-- spellchecker: enable -->
+			",
+			  ],
+			]
+		`);
+	});
+});

src/hydrate/steps/writeReadme.ts

@@ -1,4 +1,4 @@
-import * as fs from "node:fs/promises";
+import fs from "node:fs/promises";
 
 import { readFileSafe } from "../../shared/readFileSafe.js";
 import { HydrationInputValues } from "../values/types.js";
@@ -35,7 +35,12 @@ export async function writeReadme(values: HydrationInputValues) {
 
 	const endOfH1 = findH1Close(contents);
 
-	contents = [generateTopContent(values), contents.slice(endOfH1)].join("");
+	contents = [generateTopContent(values), contents.slice(endOfH1)]
+		.join("")
+		.replace(/\[!\[.+\]\(.+\)\]\(.+\)/g, "")
+		.replace(/!\[.+\]\(.+\)/g, "")
+		.replaceAll("\r", "")
+		.replaceAll("\n\n\n", "\n\n");
 
 	if (!contents.includes(contributorsIndicator)) {
 		contents = [contents, allContributorsContent].join("\n\n");