feat: Add --prompt-file CLI option (#29)

* feat: Add --prompt-file CLI option

* Fix tests

Author: nzakas

.github/copilot-instructions.md

@@ -36,14 +36,42 @@ x => x + x
 
 ```javascript
 for (let i = 0, n = str.length; i < 10; i++) {
-    if (x < 10) {
-        foo();
-    }
+	if (x < 10) {
+		foo();
+	}
 }
 
 function f(x: number, y: string): void { }
 ```
 
+## Project Structure
+
+- Use `src` for source code
+    - TypeScript types are found in `src/types.ts`
+- Use `tests` for test code
+    - Test files have the same name as the source file they are testing, but with a `.test.js` suffix
+    - Use a `fixtures` subfolder in `tests` for test data files (e.g., prompt files)
+
+## Coding Approach
+
+- Tests should always be updated to reflect the latest changes, especially for new CLI flags or options (e.g., `--prompt-file`)
+- The README file should always be updated to document new CLI options and usage examples
+- Use `async/await` for asynchronous code
+- Use `Promise.all` for parallel asynchronous code
+- When adding CLI flags, ensure argument parsing uses camelCase in code and kebab-case for CLI, and map as needed
+- Always handle file paths robustly in tests (prefer `path.resolve` for test fixture files)
+- `console` can only be used in `cli.js`.
+    - Use `console.log` for logging messages to the user
+    - Use `console.error` for errors
+    - Do not use `console` for debugging (except for temporary debug output during test troubleshooting)
+
+## Commands
+
+- Use `npm test` to run all tests
+    - To test an individual file use `npx mocha tests/<test-file>.test.js`
+- Use `npm run lint` to run the linter
+- Use `npm run fmt` to format the code
+
 ## OpenAI API
 
 For OpenAI API calls, we use the Responses API.

README.md

@@ -42,6 +42,7 @@ npx social-changelog --org <org> --repo <repo> --name <project-name>
 - `--repo, -r` - The repository name
 - `--name, -n` - (Optional) The display name of the project (defaults to org/repo)
 - `--tag, -t` - (Optional) Specific release tag to use (defaults to latest)
+- `--prompt-file` - (Optional) Path to a file containing a custom prompt to use instead of the default
 - `--help, -h` - Show help information
 
 ### CLI Examples
@@ -52,6 +53,12 @@ Generate post for latest release:
 npx social-changelog --org humanwhocodes --repo social-changelog
 ```
 
+Use a custom prompt file:
+
+```bash
+npx social-changelog --org humanwhocodes --repo social-changelog --prompt-file ./my-prompt.txt
+```
+
 By default, the `org/repo` will be used as the project name. You can override this by providing the `--name` option:
 
 ```bash

package.json

@@ -45,7 +45,7 @@
     "fmt": "prettier --write .",
     "prepublishOnly": "npm run build",
     "pretest": "npm run build",
-    "test:unit": "mocha --exit tests/**/*.*",
+    "test:unit": "mocha --exit tests/**/*.js",
     "test:jsr": "npx jsr@latest publish --dry-run",
     "test": "npm run test:unit"
   },

src/cli.js

@@ -80,14 +80,28 @@ export class CLI {
 		const token = this.#env.OPENAI_API_KEY;
 		const name = flags.name || `${org}/${repo}`;
 
+		let prompt = "";
+		if (flags.promptFile) {
+			try {
+				const fsp = await import("node:fs/promises");
+				prompt = await fsp.readFile(flags.promptFile, "utf8");
+			} catch (err) {
+				const message =
+					err instanceof Error ? err.message : String(err);
+				this.#console.error(`Error reading prompt file: ${message}`);
+				return 1;
+			}
+		}
+
 		try {
 			const release = await fetchRelease(`${org}/${repo}`, flags.tag);
 			const generator = githubToken
 				? new ChatCompletionPostGenerator(githubToken, {
 						baseUrl: GITHUB_BASE_URL,
 						model: GITHUB_MODEL,
+						prompt,
 					})
-				: new ResponseAPIPostGenerator(token);
+				: new ResponseAPIPostGenerator(token, { prompt });
 			const post = await generator.generateSocialPost(name, release);
 
 			this.#console.log(post);
@@ -97,7 +111,6 @@ export class CLI {
 			);
 			return 1;
 		}
-
 		return 0;
 	}
 
@@ -115,11 +128,18 @@ export class CLI {
 				name: { type: "string", short: "n" },
 				tag: { type: "string", short: "t" },
 				help: { type: "boolean", short: "h" },
+				"prompt-file": { type: "string" },
 			},
 			allowPositionals: false,
 			strict: false,
 		});
 
+		// Map kebab-case to camelCase for CLIArgs
+		if ("prompt-file" in flags) {
+			flags.promptFile = flags["prompt-file"];
+			delete flags["prompt-file"];
+		}
+
 		return /** @type {CLIArgs} */ (flags);
 	}
 
@@ -136,6 +156,7 @@ export class CLI {
 		this.#console.log("  --repo, -r The repository name");
 		this.#console.log("  --name, -n The name of the project");
 		this.#console.log("  --tag,  -t The release tag [default: latest]");
+		this.#console.log("  --prompt-file  Path to a custom prompt file");
 		this.#console.log("  --help, -h Show this help message");
 		this.#console.log("");
 	}

src/types.ts

@@ -146,6 +146,7 @@ export interface CLIArgs {
 	name: string | undefined;
 	tag: string | undefined;
 	help: boolean | undefined;
+	promptFile?: string;
 }
 
 export interface GptMessage {

tests/cli.test.js

@@ -7,6 +7,8 @@
 //-----------------------------------------------------------------------------
 
 import { strict as assert } from "node:assert";
+import path from "node:path";
+import fsp from "node:fs/promises";
 import { CLI } from "../src/cli.js";
 import { MockServer, FetchMocker } from "mentoss";
 
@@ -309,6 +311,57 @@ describe("CLI", () => {
 				true,
 			);
 		});
+
+		it("should use custom prompt from --prompt-file option", async () => {
+			const promptPath = path.resolve(
+				"tests",
+				"fixtures",
+				"prompt-custom.txt",
+			);
+			const customPrompt = await fsp.readFile(promptPath, "utf8");
+
+			githubServer.get("/repos/test-org/test-repo/releases/latest", {
+				status: 200,
+				body: MOCK_RELEASE,
+			});
+
+			openAIServer.post(
+				{
+					url: "/v1/responses",
+					body: {
+						instructions: customPrompt,
+					},
+				},
+				{
+					status: 200,
+					body: {
+						id: "resp_456",
+						output: [
+							{
+								content: [
+									{
+										type: "output_text",
+										text: "CUSTOMPROMPT",
+									},
+								],
+							},
+						],
+					},
+				},
+			);
+
+			const exitCode = await cli.execute([
+				"--org",
+				"test-org",
+				"--repo",
+				"test-repo",
+				"--prompt-file",
+				promptPath,
+			]);
+
+			assert.equal(exitCode, 0);
+			assert.equal(testConsole.logs[0], "CUSTOMPROMPT");
+		});
 	});
 
 	describe("showHelp()", () => {

tests/fixtures/prompt-custom.txt

@@ -0,0 +1 @@
+You are a test prompt for the CLI --prompt-file option. Only output the word: CUSTOMPROMPT

tests/prompt-custom.txt

@@ -0,0 +1 @@
+You are a test prompt for the CLI --prompt-file option. Only output the word: CUSTOMPROMPT