Add util.getFileContentsUsingAPI

src/util.test.ts

@@ -1,7 +1,10 @@
+import * as github from "@actions/github";
 import test from 'ava';
 import * as fs from 'fs';
 import * as os from "os";
+import sinon from 'sinon';
 
+import * as api from './api-client';
 import {setupTests} from './testing-utils';
 import * as util from './util';
 
@@ -150,3 +153,55 @@ test('getExtraOptionsEnvParam() fails on invalid JSON', t => {
 
   process.env.CODEQL_ACTION_EXTRA_OPTIONS = origExtraOptions;
 });
+type GetContentsResponse = { content?: string; } | {}[];
+
+function mockGetContents(content: GetContentsResponse, status: number, isDirectory = false): sinon.SinonStub<any, any> {
+  // Passing an auth token is required, so we just use a dummy value
+  let client = new github.GitHub('123');
+  const response = {
+    data: isDirectory ? [content] : content,
+    status: status
+  };
+
+  const spyGetContents = sinon.stub(client.repos, "getContents").resolves(response as any);
+  sinon.stub(api, "getApiClient").value(() => client);
+  return spyGetContents;
+}
+
+test('getFileContentsUsingAPI() throws if the request does not succeed', async t => {
+  const spyGetContents = mockGetContents({}, 400);
+  try {
+    await util.getFileContentsUsingAPI('github', 'codeql-action', 'non-existing-file', 'main');
+    throw new Error('initConfig did not throw error');
+  } catch (err) {
+    t.assert(spyGetContents.called);
+    t.deepEqual(err, new Error(util.fileDownloadError('github/codeql-action/non-existing-file@main')));
+  }
+});
+
+test('getFileContentsUsingAPI() throws if the requested file is a directory', async t => {
+  const inputFileContents = `content content content`;
+  const dummyResponse = {
+    content: Buffer.from(inputFileContents).toString("base64"),
+  };
+  const spyGetContents = mockGetContents(dummyResponse, 200, true);
+  try {
+    await util.getFileContentsUsingAPI('github', 'codeql-action', 'non-existing-file', 'main');
+    throw new Error('initConfig did not throw error');
+  } catch (err) {
+    t.assert(spyGetContents.called);
+    t.deepEqual(err, new Error(util.fileIsADirectoryError('github/codeql-action/non-existing-file@main')));
+  }
+});
+
+test('getFileContentsUsingAPI() returns the right content', async t => {
+  const inputFileContents = `content content content`;
+  const dummyResponse = {
+    content: Buffer.from(inputFileContents).toString("base64"),
+  };
+  const spyGetContents = mockGetContents(dummyResponse, 200);
+  const content = await util.getFileContentsUsingAPI('github', 'codeql-action', 'non-existing-file', 'main');
+
+  t.deepEqual(content, inputFileContents);
+  t.assert(spyGetContents.called);
+});

src/util.ts

@@ -433,3 +433,39 @@ export function getThreadsFlag(): string {
 export function getCodeQLDatabasesDir() {
   return path.resolve(getRequiredEnvParam('RUNNER_TEMP'), 'codeql_databases');
 }
+
+export function fileDownloadError(file: string): string {
+  return 'Error while trying to download `' + file + '`';
+}
+
+export function fileIsADirectoryError(file: string): string {
+  return '`' + file + '` is a directory';
+}
+
+export async function getFileContentsUsingAPI(owner: string, repo: string, path: string, ref: string): Promise<string> {
+  const response = await api.getActionsApiClient(true).repos.getContents({
+    owner: owner,
+    repo: repo,
+    path: path,
+    ref: ref,
+  });
+
+  const file = [owner, repo, path].join('/') + '@' + ref;
+
+  if (response.status !== 200) {
+    throw new Error(fileDownloadError(file));
+  }
+
+  if (Array.isArray(response.data)) {
+    throw new Error(fileIsADirectoryError(file));
+  }
+
+  let fileContents: string;
+  if ("content" in response.data && response.data.content !== undefined) {
+    fileContents = response.data.content;
+  } else {
+    throw new Error(fileDownloadError(file));
+  }
+
+  return Buffer.from(fileContents, 'base64').toString('binary');
+}