feat: add Bun

Author: velut

src/bun.ts

@@ -0,0 +1,31 @@
+import { execa } from "execa";
+
+/** `Bun` is a wrapper for the Bun package manager. */
+export class Bun {
+	#bunCmd: string;
+
+	constructor(bunCmd = "bun") {
+		this.#bunCmd = bunCmd.trim();
+	}
+
+	/**
+	`add` installs the given package in the given directory and
+	returns a list of all installed packages (e.g., `["foo@1.0.0"]`).
+
+	@see {@link https://bun.sh/docs/cli/add}
+	*/
+	async add(pkg: string, cwd: string): Promise<string[]> {
+		// Run `bun add <pkg> --verbose` in the `cwd`.
+		const { stdout } = await execa(this.#bunCmd, ["add", pkg, "--verbose"], { cwd });
+
+		// With verbose output on, bun prints one line per installed package
+		// (e.g., "foo@1.0.0"), including all installed dependencies.
+		// These lines are between the two delimiting lines found here:
+		// https://github.com/oven-sh/bun/blob/972a7b7080bd3066b54dcb43e9c91c5dfa26a69c/src/install/lockfile.zig#L5369-L5370.
+		const lines = stdout.split("\n");
+		const beginHash = lines.findIndex((line) => line.startsWith("-- BEGIN SHA512/256"));
+		const endHash = lines.findIndex((line) => line.startsWith("-- END HASH"));
+		const installedPackages = lines.slice(beginHash + 1, endHash);
+		return installedPackages;
+	}
+}