Split up GitHub context functions, provide fork info

src/git.js

@@ -48,12 +48,11 @@ function hasChanges() {
 
 /**
  * Pushes all changes to the GitHub repository
- * @param {{actor: string, branch: string, event: object, eventName: string, repository: string,
- * token: string, username: string, workspace: string}} context - Object information about the
- * GitHub repository and action trigger event
+ * @param {import('./github/context').GithubContext} context - Information about the GitHub
+ * repository and action trigger event
  */
 function pushChanges(context) {
-	const remote = `https://${context.actor}:${context.token}@github.com/${context.username}/${context.repository}.git`;
+	const remote = `https://${context.actor}:${context.token}@github.com/${context.repository.repoName}.git`;
 	const localBranch = "HEAD";
 	const remoteBranch = context.branch;
 

src/github/api.js

@@ -0,0 +1,68 @@
+const { name: actionName } = require("../../package");
+const { log } = require("../utils/action");
+const request = require("../utils/request");
+const { capitalizeFirstLetter } = require("../utils/string");
+
+/**
+ * Creates a new check on GitHub which annotates the relevant commit with linting errors
+ * @param {string} linterName - Name of the linter for which a check should be created
+ * @param {string} sha - SHA of the commit which should be annotated
+ * @param {import('./context').GithubContext} context - Information about the GitHub repository and
+ * action trigger event
+ * @param {{isSuccess: boolean, warning: [], error: []}} lintResult - Parsed lint result
+ * @param {string} summary - Summary for the GitHub check
+ */
+async function createCheck(linterName, sha, context, lintResult, summary) {
+	let annotations = [];
+	for (const level of ["warning", "error"]) {
+		annotations = [
+			...annotations,
+			...lintResult[level].map(result => ({
+				path: result.path,
+				start_line: result.firstLine,
+				end_line: result.lastLine,
+				annotation_level: level === "warning" ? "warning" : "failure",
+				message: result.message,
+			})),
+		];
+	}
+
+	// Only use the first 50 annotations (limit for a single API request)
+	if (annotations.length > 50) {
+		log(
+			`There are more than 50 errors/warnings from ${linterName}. Annotations are created for the first 50 issues only.`,
+		);
+		annotations = annotations.slice(0, 50);
+	}
+
+	const body = {
+		name: linterName,
+		head_sha: sha,
+		conclusion: lintResult.isSuccess ? "success" : "failure",
+		output: {
+			title: capitalizeFirstLetter(summary),
+			summary: `${linterName} found ${summary}`,
+			annotations,
+		},
+	};
+	try {
+		log(`Creating GitHub check with ${annotations.length} annotations for ${linterName}…`);
+		await request(`https://api.github.com/repos/${context.repository.repoName}/check-runs`, {
+			method: "POST",
+			headers: {
+				"Content-Type": "application/json",
+				// "Accept" header is required to access Checks API during preview period
+				Accept: "application/vnd.github.antiope-preview+json",
+				Authorization: `Bearer ${context.token}`,
+				"User-Agent": actionName,
+			},
+			body,
+		});
+		log(`${linterName} check created successfully`);
+	} catch (err) {
+		log(err, "error");
+		throw new Error(`Error trying to create GitHub check for ${linterName}: ${err.message}`);
+	}
+}
+
+module.exports = { createCheck };

src/github/context.js

@@ -0,0 +1,116 @@
+const { readFileSync } = require("fs");
+
+const { name: actionName } = require("../../package");
+const { getEnv, getInput } = require("../utils/action");
+
+/**
+ * GitHub Actions workflow's environment variables
+ * @typedef {{actor: string, eventName: string, eventPath: string, token: string, workspace:
+ * string}} ActionEnv
+ */
+
+/**
+ * Information about the GitHub repository and its fork (if it exists)
+ * @typedef {{repoName: string, forkName: string, hasFork: boolean}} GithubRepository
+ */
+
+/**
+ * Information about the GitHub repository and action trigger event
+ * @typedef {{actor: string, branch: string, event: object, eventName: string, repository:
+ * GithubRepository, token: string, workspace: string}} GithubContext
+ */
+
+/**
+ * Returns the GitHub Actions workflow's environment variables
+ * @returns {ActionEnv} GitHub Actions workflow's environment variables
+ */
+function parseActionEnv() {
+	return {
+		// Information provided by environment
+		actor: getEnv("github_actor", true),
+		eventName: getEnv("github_event_name", true),
+		eventPath: getEnv("github_event_path", true),
+		workspace: getEnv("github_workspace", true),
+
+		// Information provided by action user
+		token: getInput("github_token", true),
+	};
+}
+
+/**
+ * Parse `event.json` file (file with the complete webhook event payload, automatically provided by
+ * GitHub)
+ * @param {string} eventPath - Path to the `event.json` file
+ * @returns {object} - Webhook event payload
+ */
+function parseEnvFile(eventPath) {
+	const eventBuffer = readFileSync(eventPath);
+	return JSON.parse(eventBuffer);
+}
+
+/**
+ * Parses the name of the current branch from the GitHub webhook event
+ * @param {string} eventName - GitHub event type
+ * @param {object} event - GitHub webhook event payload
+ * @returns {string} - Branch name
+ */
+function parseBranch(eventName, event) {
+	if (eventName === "push") {
+		return event.ref.substring(11); // Remove "refs/heads/" from start of string
+	}
+	if (eventName === "pull_request") {
+		return event.pull_request.head.ref;
+	}
+	throw Error(`${actionName} does not support "${eventName}" GitHub events`);
+}
+
+/**
+ * Parses the name of the current repository and determines whether it has a corresponding fork.
+ * Fork detection is only supported for the "pull_request" event
+ * @param {string} eventName - GitHub event type
+ * @param {object} event - GitHub webhook event payload
+ * @returns {GithubRepository} - Information about the GitHub repository and its fork (if it exists)
+ */
+function parseRepository(eventName, event) {
+	const repoName = event.repository.full_name;
+	let forkName;
+	if (eventName === "pull_request") {
+		// "pull_request" events are triggered on the repository where the PR is made. The PR branch can
+		// be on the same repository (`forkRepository` is set to `null`) or on a fork (`forkRepository`
+		// is defined)
+		const headRepoName = event.pull_request.head.repo.full_name;
+		forkName = repoName === headRepoName ? undefined : headRepoName;
+	}
+	return {
+		repoName,
+		forkName,
+		hasFork: forkName != null && forkName !== repoName,
+	};
+}
+
+/**
+ * Returns information about the GitHub repository and action trigger event
+ * @returns {GithubContext} context - Information about the GitHub repository and action trigger
+ * event
+ */
+function getContext() {
+	const { actor, eventName, eventPath, token, workspace } = parseActionEnv();
+	const event = parseEnvFile(eventPath);
+	return {
+		actor,
+		branch: parseBranch(eventName, event),
+		event,
+		eventName,
+		repository: parseRepository(eventName, event),
+		token,
+		workspace,
+	};
+}
+
+module.exports = {
+	getContext,
+	parseActionEnv,
+	parseBranch,
+	parseEnvFile,
+	parseRepository,
+};

src/index.js

@@ -1,7 +1,8 @@
 const { join } = require("path");
 
 const git = require("./git");
-const github = require("./github");
+const { createCheck } = require("./github/api");
+const { getContext } = require("./github/context");
 const linters = require("./linters");
 const { getInput, log } = require("./utils/action");
 const { getSummary } = require("./utils/lint-result");
@@ -19,7 +20,7 @@ process.on("unhandledRejection", err => {
  * Parses the action configuration and runs all enabled linters on matching files
  */
 async function runAction() {
-	const context = github.getContext();
+	const context = getContext();
 	const autoFix = getInput("auto_fix") === "true";
 	const commitMsg = getInput("commit_message", true);
 
@@ -85,7 +86,7 @@ async function runAction() {
 	const headSha = git.getHeadSha();
 	await Promise.all(
 		checks.map(({ checkName, lintResult, summary }) =>
-			github.createCheck(checkName, headSha, context, lintResult, summary),
+			createCheck(checkName, headSha, context, lintResult, summary),
 		),
 	);
 }

test/github/api.test.js

@@ -0,0 +1,48 @@
+const { createCheck } = require("../../src/github/api");
+const {
+	EVENT_NAME,
+	EVENT_PATH,
+	FORK_REPOSITORY,
+	REPOSITORY,
+	REPOSITORY_DIR,
+	TOKEN,
+	USERNAME,
+} = require("./test-constants");
+
+jest.mock("../../src/utils/request", () =>
+	// eslint-disable-next-line global-require
+	jest.fn().mockReturnValue(require("./api-responses/check-runs.json")),
+);
+
+describe("createCheck()", () => {
+	const LINT_RESULT = {
+		isSuccess: true,
+		warning: [],
+		error: [],
+	};
+	const context = {
+		actor: USERNAME,
+		event: {},
+		eventName: EVENT_NAME,
+		eventPath: EVENT_PATH,
+		repository: {
+			repoName: REPOSITORY,
+			forkName: FORK_REPOSITORY,
+			hasFork: false,
+		},
+		token: TOKEN,
+		workspace: REPOSITORY_DIR,
+	};
+
+	test("mocked request should be successful", async () => {
+		await expect(
+			createCheck("check-name", "sha", context, LINT_RESULT, "summary"),
+		).resolves.toEqual(undefined);
+	});
+
+	test("mocked request should fail when no lint results are provided", async () => {
+		await expect(createCheck("check-name", "sha", context, null, "summary")).rejects.toEqual(
+			expect.any(Error),
+		);
+	});
+});