Update license tests in preparation for new year

ts/util/lint/license_comments.ts

@@ -0,0 +1,165 @@
+// Copyright 2020 Signal Messenger, LLC
+// SPDX-License-Identifier: AGPL-3.0-only
+
+// This file doesn't check the format of license files, just the end year. See
+//   `license_comments_test.ts` for those checks, which are meant to be run more often.
+
+import assert from 'assert';
+import * as readline from 'readline';
+import * as path from 'path';
+import * as fs from 'fs';
+import { promisify } from 'util';
+import * as childProcess from 'child_process';
+import pMap from 'p-map';
+
+const exec = promisify(childProcess.exec);
+
+const rootPath = path.join(__dirname, '..', '..');
+
+const EXTENSIONS_TO_CHECK = new Set([
+  '.eslintignore',
+  '.gitattributes',
+  '.gitignore',
+  '.nvmrc',
+  '.prettierignore',
+  '.sh',
+  '.snyk',
+  '.yarnclean',
+  '.yml',
+  '.js',
+  '.scss',
+  '.ts',
+  '.tsx',
+  '.html',
+  '.md',
+  '.plist',
+]);
+const FILES_TO_IGNORE = new Set([
+  'ISSUE_TEMPLATE.md',
+  'Mp3LameEncoder.min.js',
+  'PULL_REQUEST_TEMPLATE.md',
+  'WebAudioRecorderMp3.js',
+]);
+
+// This is not technically the real extension.
+function getExtension(file: string): string {
+  if (file.startsWith('.')) {
+    return getExtension(`x.${file}`);
+  }
+  return path.extname(file);
+}
+
+export async function forEachRelevantFile(
+  fn: (_: string) => Promise<unknown>
+): Promise<void> {
+  const gitFiles = (
+    await exec('git ls-files', { cwd: rootPath, env: {} })
+  ).stdout
+    .split(/\n/g)
+    .map(line => line.trim())
+    .filter(Boolean)
+    .map(file => path.join(rootPath, file));
+
+  await pMap(
+    gitFiles,
+    async (file: string) => {
+      if (
+        FILES_TO_IGNORE.has(path.basename(file)) ||
+        path.relative(rootPath, file).startsWith('components')
+      ) {
+        return;
+      }
+
+      const extension = getExtension(file);
+      if (!EXTENSIONS_TO_CHECK.has(extension)) {
+        return;
+      }
+
+      await fn(file);
+    },
+    // Without this, we may run into "too many open files" errors.
+    { concurrency: 100 }
+  );
+}
+
+export function readFirstLines(
+  file: string,
+  count: number
+): Promise<Array<string>> {
+  return new Promise(resolve => {
+    const lines: Array<string> = [];
+
+    const lineReader = readline.createInterface({
+      input: fs.createReadStream(file),
+    });
+    lineReader.on('line', line => {
+      lines.push(line);
+      if (lines.length >= count) {
+        lineReader.close();
+      }
+    });
+    lineReader.on('close', () => {
+      resolve(lines);
+    });
+  });
+}
+
+async function getLatestCommitYearForFile(file: string): Promise<number> {
+  const dateString = (
+    await new Promise<string>((resolve, reject) => {
+      let result = '';
+      // We use the more verbose `spawn` to avoid command injection, in case the filename
+      //   has strange characters.
+      const gitLog = childProcess.spawn(
+        'git',
+        ['log', '-1', '--format=%as', file],
+        {
+          cwd: rootPath,
+          env: { PATH: process.env.PATH },
+        }
+      );
+      gitLog.stdout?.on('data', data => {
+        result += data.toString('utf8');
+      });
+      gitLog.on('close', code => {
+        if (code === 0) {
+          resolve(result);
+        } else {
+          reject(new Error(`git log failed with exit code ${code}`));
+        }
+      });
+    })
+  ).trim();
+
+  const result = new Date(dateString).getFullYear();
+  assert(!Number.isNaN(result), `Could not read commit year for ${file}`);
+  return result;
+}
+
+async function main() {
+  const currentYear = new Date().getFullYear() + 1;
+
+  await forEachRelevantFile(async file => {
+    const [firstLine] = await readFirstLines(file, 1);
+    const { groups = {} } =
+      firstLine.match(/(?:\d{4}-)?(?<endYearString>\d{4})/) || [];
+    const { endYearString } = groups;
+    const endYear = Number(endYearString);
+
+    assert(
+      endYear === currentYear ||
+        endYear === (await getLatestCommitYearForFile(file)),
+      `${file} has an invalid end license year`
+    );
+  });
+}
+
+// Note: this check will fail if we switch to ES modules. See
+//  <https://stackoverflow.com/a/60309682>.
+if (require.main === module) {
+  main().catch(err => {
+    // eslint-disable-next-line no-console
+    console.error(err);
+    process.exit(1);
+  });
+}