test: add more tests to hydrate flow (#578)

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## PR Checklist

- [x] Addresses an existing open issue: fixes #447
- [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

Added more tests across the `getHydrationDefaults` flow, also addressing
a bug where `readTitleFromReadme` only matched the first word of the
title.

Author: RNR1

src/hydrate/readFileSafe.test.ts

@@ -0,0 +1,29 @@
+import { describe, expect, it, vi } from "vitest";
+
+import { readFileSafe } from "./readFileSafe.js";
+
+const mockReadFile = vi.fn();
+
+vi.mock("node:fs/promises", () => ({
+	get default() {
+		return {
+			get readFile() {
+				return mockReadFile;
+			},
+		};
+	},
+}));
+
+describe("readFundingIfExists", () => {
+	it("outputs the file content as string when it exists", async () => {
+		mockReadFile.mockResolvedValue("File content as string");
+		const result = await readFileSafe("/path/to/file.ext", "fallback");
+		expect(result).toBe("File content as string");
+	});
+
+	it("returns fallback when readFile fails", async () => {
+		mockReadFile.mockRejectedValue("Oops");
+		const result = await readFileSafe("/path/to/nowhere.ext", "fallback");
+		expect(result).toBe("fallback");
+	});
+});

src/hydrate/values/getHydrationDefaults.test.ts

@@ -0,0 +1,55 @@
+import { describe, expect, it, vi } from "vitest";
+
+import { getHydrationDefaults } from "./getHydrationDefaults.js";
+
+const mockReadFileSafe = vi.fn();
+
+vi.mock("../readFileSafe.js", () => ({
+	get readFileSafe() {
+		return mockReadFileSafe;
+	},
+}));
+
+const mockReadFundingIfExists = vi.fn();
+
+vi.mock("./readFundingIfExists.js", () => ({
+	get readFundingIfExists() {
+		return mockReadFundingIfExists;
+	},
+}));
+
+const mockReadOwnerFromGitRemote = vi.fn();
+
+vi.mock("./readOwnerFromGitRemote.js", () => ({
+	get readOwnerFromGitRemote() {
+		return mockReadOwnerFromGitRemote;
+	},
+}));
+
+const mockReadTitleFromReadme = vi.fn();
+
+vi.mock("./readTitleFromReadme.js", () => ({
+	get readTitleFromReadme() {
+		return mockReadTitleFromReadme;
+	},
+}));
+
+describe("getHydrationDefaults", () => {
+	it("reads hydration defaults from existing readme and package json when exists", async () => {
+		mockReadTitleFromReadme.mockResolvedValue("My Awesome Package");
+		mockReadFileSafe.mockResolvedValueOnce(
+			'{"author":"Someone <[email protected]>"}'
+		);
+		mockReadFundingIfExists.mockResolvedValue("Someone");
+		mockReadOwnerFromGitRemote.mockResolvedValue("SUM1");
+
+		const result = await getHydrationDefaults();
+		expect(await result.author()).toBe("Someone");
+		expect(await result.email()).toBe("[email protected]");
+		expect(await result.funding()).toBe("Someone");
+		expect(await result.owner()).toBe("SUM1");
+		expect(result.releases).toBe(true);
+		expect(await result.title()).toBe("My Awesome Package");
+		expect(result.unitTests).toBe(true);
+	});
+});

src/hydrate/values/getHydrationDefaults.ts

@@ -5,9 +5,9 @@ import { readAuthorIfExists } from "./readAuthorIfExists.js";
 import { readEmailIfExists } from "./readEmailIfExists.js";
 import { readFundingIfExists } from "./readFundingIfExists.js";
 import { readOwnerFromGitRemote } from "./readOwnerFromGitRemote.js";
+import { readTitleFromReadme } from "./readTitleFromReadme.js";
 
 export async function getHydrationDefaults() {
-	const existingReadme = await readFileSafe("./README.md", "");
 	const existingPackage = JSON.parse(
 		await readFileSafe("./package.json", "{}")
 	) as PartialPackageData;
@@ -18,7 +18,7 @@ export async function getHydrationDefaults() {
 		funding: readFundingIfExists,
 		owner: readOwnerFromGitRemote,
 		releases: true,
-		title: existingReadme.match(/^(?:# |<h1\s+align="center">)(\S+)/)?.[1],
+		title: readTitleFromReadme,
 		unitTests: true,
 	};
 }

src/hydrate/values/readTitleFromReadme.test.ts

@@ -0,0 +1,33 @@
+import { describe, expect, it, vi } from "vitest";
+
+import { readTitleFromReadme } from "./readTitleFromReadme.js";
+
+const mockReadFileSafe = vi.fn();
+
+vi.mock("../readFileSafe.js", () => ({
+	get readFileSafe() {
+		return mockReadFileSafe;
+	},
+}));
+
+describe("readTitleFromReadme", () => {
+	it('reads title as markdown from "README.md" when it exists', async () => {
+		mockReadFileSafe.mockResolvedValue("# My Awesome Package");
+		const result = await readTitleFromReadme();
+		expect(result).toBe("My Awesome Package");
+	});
+
+	it('reads title as HTML from "README.md" when it exists', async () => {
+		mockReadFileSafe.mockResolvedValue(
+			'<h1 align="center">My Awesome Package</h1>'
+		);
+		const result = await readTitleFromReadme();
+		expect(result).toBe("My Awesome Package");
+	});
+
+	it("returns undefined when title does not exist", async () => {
+		mockReadFileSafe.mockResolvedValue("");
+		const result = await readTitleFromReadme();
+		expect(result).toBe("");
+	});
+});

src/hydrate/values/readTitleFromReadme.ts

@@ -0,0 +1,10 @@
+import { readFileSafe } from "../readFileSafe.js";
+
+export async function readTitleFromReadme() {
+	return (
+		(await readFileSafe("./README.md", ""))
+			.match(/^(?:# |<h1\s+align="center">)(.*?)(?:<\/h1>)?$/i)?.[1]
+			?.trim()
+			.replace(/<[^>]+(?:>|$)/g, "") ?? ""
+	);
+}