fix: don't pnpm remove an empty list of packages (#727)

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## PR Checklist

- [x] Addresses an existing open issue: fixes #724
- [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

Refactors the two existing package removal functions to be just one.

Author: JoshuaKGoldberg

src/shared/packages.test.ts

@@ -0,0 +1,66 @@
+import { describe, expect, it, vi } from "vitest";
+
+import { removeDependencies } from "./packages.js";
+
+const mockExecaCommand = vi.fn();
+
+vi.mock("execa", () => ({
+	get execaCommand() {
+		return mockExecaCommand;
+	},
+}));
+
+describe("removeDependencies", () => {
+	it("removes all packages that already exist when all already exist", async () => {
+		await removeDependencies(["one", "two"], {
+			one: "1.2.3",
+			two: "4.5.6",
+		});
+
+		expect(mockExecaCommand.mock.calls).toMatchInlineSnapshot(`
+			[
+			  [
+			    "pnpm remove one two",
+			  ],
+			]
+		`);
+	});
+
+	it("removes only packages that already exist when some don't exist", async () => {
+		await removeDependencies(["exists", "missing"], {
+			exists: "1.2.3",
+		});
+
+		expect(mockExecaCommand.mock.calls).toMatchInlineSnapshot(`
+			[
+			  [
+			    "pnpm remove exists",
+			  ],
+			]
+		`);
+	});
+
+	it("adds a flag to removing packages when one is provided", async () => {
+		await removeDependencies(
+			["exists", "missing"],
+			{
+				exists: "1.2.3",
+			},
+			"-D",
+		);
+
+		expect(mockExecaCommand.mock.calls).toMatchInlineSnapshot(`
+			[
+			  [
+			    "pnpm remove exists -D",
+			  ],
+			]
+		`);
+	});
+
+	it("does nothing when no packages already exist", async () => {
+		await removeDependencies(["missing"]);
+
+		expect(mockExecaCommand.mock.calls).toMatchInlineSnapshot("[]");
+	});
+});

src/shared/packages.ts

@@ -1,4 +1,4 @@
-import { $ } from "execa";
+import { execaCommand } from "execa";
 
 import { readFileSafe } from "./readFileSafe.js";
 import { PartialPackageData } from "./types.js";
@@ -11,22 +11,14 @@ export async function readPackageData() {
 
 export async function removeDependencies(
 	packageNames: string[],
-	packageData: PartialPackageData,
+	existing: Record<string, string> = {},
+	flags = "",
 ) {
-	await $`pnpm remove ${packageNames.filter(
-		packageExists(packageData.dependencies),
-	)}`;
-}
-
-export async function removeDevDependencies(
-	packageNames: string[],
-	packageData: PartialPackageData,
-) {
-	await $`pnpm remove ${packageNames.filter(
-		packageExists(packageData.devDependencies),
-	)} -D`;
-}
+	const present = packageNames.filter((packageName) => packageName in existing);
 
-function packageExists(listing: Record<string, string> = {}) {
-	return (packageName: string) => packageName in listing;
+	if (present.length) {
+		await execaCommand(
+			`pnpm remove ${present.join(" ")}${flags ? ` ${flags}` : ""}`,
+		);
+	}
 }

src/steps/finalizeDependencies.test.ts

@@ -11,13 +11,9 @@ vi.mock("execa", () => ({
 	},
 }));
 
-const mockRemoveDevDependencies = vi.fn();
-
 vi.mock("../shared/packages.js", () => ({
 	readPackageData: () => [],
-	get removeDevDependencies() {
-		return mockRemoveDevDependencies;
-	},
+	removeDependencies: vi.fn(),
 }));
 
 const options = {

src/steps/finalizeDependencies.ts

@@ -1,6 +1,6 @@
 import { execaCommand } from "execa";
 
-import { readPackageData, removeDevDependencies } from "../shared/packages.js";
+import { readPackageData, removeDependencies } from "../shared/packages.js";
 import { Options } from "../shared/types.js";
 
 export async function finalizeDependencies(options: Options) {
@@ -68,9 +68,10 @@ export async function finalizeDependencies(options: Options) {
 
 	if (!options.excludeContributors) {
 		await execaCommand(`npx all-contributors-cli generate`);
-		await removeDevDependencies(
+		await removeDependencies(
 			["all-contributors-cli", "all-contributors-for-repository"],
-			await readPackageData(),
+			(await readPackageData()).devDependencies,
+			"-D",
 		);
 	}
 

src/steps/uninstallPackages.ts

@@ -1,10 +1,6 @@
 import { $ } from "execa";
 
-import {
-	readPackageData,
-	removeDependencies,
-	removeDevDependencies,
-} from "../shared/packages.js";
+import { readPackageData, removeDependencies } from "../shared/packages.js";
 
 export async function uninstallPackages() {
 	const packageData = await readPackageData();
@@ -24,10 +20,10 @@ export async function uninstallPackages() {
 			"replace-in-file",
 			"title-case",
 		],
-		packageData,
+		packageData.dependencies,
 	);
 
-	await removeDevDependencies(
+	await removeDependencies(
 		[
 			"@octokit/request-error",
 			"@types/git-url-parse",
@@ -38,7 +34,8 @@ export async function uninstallPackages() {
 			"globby",
 			"tsx",
 		],
-		packageData,
+		packageData.devDependencies,
+		"-D",
 	);
 
 	await $`pnpm add prettier -D`;