utils.ts too

Author: JoshuaKGoldberg

.DS_Store

@@ -0,0 +1,37 @@
+import { describe, expect, it, vi } from "vitest";
+
+import { execOrThrow } from "./utils.js";
+
+const mockExec = vi.fn();
+
+vi.mock("node:child_process", () => ({
+	default: {
+		get exec() {
+			return mockExec;
+		},
+	},
+}));
+
+describe("execOrThrow", () => {
+	it("throws an error when exec prints to stderr", async () => {
+		mockExec.mockImplementation((command, callback) => {
+			callback(null, { stderr: "Oh no!" });
+		});
+
+		await expect(
+			async () => await execOrThrow("ls"),
+		).rejects.toMatchInlineSnapshot(`[Error: Oh no!]`);
+	});
+
+	it("returns stdout when exec doesn't print to stderr", async () => {
+		const stdout = "abc123";
+
+		mockExec.mockImplementation((command, callback) => {
+			callback(null, { stdout });
+		});
+
+		const actual = await execOrThrow("ls");
+
+		expect(actual).toEqual(stdout);
+	});
+});

src/utils.test.ts

@@ -1,9 +1,8 @@
 import cp from "node:child_process";
 import { promisify } from "node:util";
 
-const exec = promisify(cp.exec);
-
 export async function execOrThrow(command: string) {
+	const exec = promisify(cp.exec);
 	const { stderr, stdout } = await exec(command);
 
 	if (stderr) {