feat: Command and "Runner" Pattern for release-please

- Moves Yargs command parser to an isolated file (for reuse and testing).
- Updates command handlers to use a shared "runner" module in order to centralize execuation and configuration parsing.
- Adds `changelog-types` option
- Adds ability to configure the CLI tool using a JSON file (via '--config' flag)

see googleapis#511

__snapshots__/runner.js

@@ -0,0 +1,18 @@
+exports['Runner release-pr allows customization of changelog sections 1'] = `
+[
+  [
+    "CHANGELOG.md",
+    {
+      "content": "# Changelog\\n\\n### [1.0.1](https://github.com/googleapis/release-please/compare/v1.0.0...v1.0.1) (1983-10-10)\\n\\n\\n### Other\\n\\n* **deps:** update dependency com.google.cloud:google-cloud-spanner to v1.50.0 ([1f9663c](https://github.com/googleapis/release-please/commit/1f9663cf08ab1cf3b68d95dee4dc99b7c4aac373))\\n* **deps:** update dependency com.google.cloud:google-cloud-storage to v1.120.0 ([fcd1c89](https://github.com/googleapis/release-please/commit/fcd1c890dc1526f4d62ceedad561f498195c8939))\\n* update common templates ([3006009](https://github.com/googleapis/release-please/commit/3006009a2b1b2cb4bd5108c0f469c410759f3a6a))\\n",
+      "mode": "100644"
+    }
+  ],
+  [
+    "package.json",
+    {
+      "content": "{\\n  \\"name\\": \\"runner-package\\",\\n  \\"version\\": \\"1.0.1\\"\\n}\\n",
+      "mode": "100644"
+    }
+  ]
+]
+`

src/bin/command.ts

@@ -0,0 +1,200 @@
+#!/usr/bin/env node
+
+// Copyright 2020 Google LLC
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//      http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+import chalk = require('chalk');
+import {coerceOption} from '../util/coerce-option';
+import {GitHubReleaseOptions} from '../github-release';
+import {ReleasePROptions} from '../release-pr';
+import {getReleaserNames} from '../releasers';
+import main from '../runner';
+import * as yargs from 'yargs';
+
+export interface ErrorObject {
+  body?: object;
+  status?: number;
+  message: string;
+  stack: string;
+}
+
+interface YargsOptions {
+  describe: string;
+  choices?: string[];
+  demand?: boolean;
+  type?: string;
+  default?: string | boolean;
+}
+
+interface YargsOptionsBuilder {
+  option(opt: string, options: YargsOptions): YargsOptionsBuilder;
+}
+
+export default yargs
+  .config('config')
+  .command(
+    'release-pr',
+    'create or update a PR representing the next release',
+    (yargs: YargsOptionsBuilder) => {
+      yargs
+        .option('package-name', {
+          describe: 'name of package release is being minted for',
+          demand: true,
+        })
+        .option('changelog-types', {
+          describe:
+            'a JSON formatted string containing to override the outputted changelog sections',
+        })
+        .option('version-file', {
+          describe: 'path to version file to update, e.g., version.rb',
+        })
+        .option('last-package-version', {
+          describe: 'last version # that package was released as',
+        })
+        .option('repo-url', {
+          describe: 'GitHub URL to generate release for',
+          demand: true,
+        })
+        .option('fork', {
+          describe: 'should the PR be created from a fork',
+          type: 'boolean',
+          default: false,
+        })
+        .option('label', {
+          describe: 'label(s) to add to generated PR',
+        })
+        .option('snapshot', {
+          describe: 'is it a snapshot (or pre-release) being generated?',
+          type: 'boolean',
+          default: false,
+        })
+        .option('default-branch', {
+          describe: 'default branch to open release PR against',
+          type: 'string',
+        })
+        .option('path', {
+          describe: 'release from path other than root directory',
+          type: 'string',
+        })
+        .option('monorepo-tags', {
+          describe: 'include library name in tags and release branches',
+          type: 'boolean',
+          default: false,
+        });
+    },
+    async (argv: ReleasePROptions & yargs.Arguments) => {
+      await main(argv, 'release-pr').catch(e => handleError(e, argv));
+    }
+  )
+  .command(
+    'github-release',
+    'create a GitHub release from a release PR',
+    (yargs: YargsOptionsBuilder) => {
+      yargs
+        .option('package-name', {
+          describe: 'name of package release is being minted for',
+        })
+        .option('repo-url', {
+          describe: 'GitHub URL to generate release for',
+          demand: true,
+        })
+        .option('changelog-path', {
+          default: 'CHANGELOG.md',
+          describe: 'where can the CHANGELOG be found in the project?',
+        })
+        .option('label', {
+          default: 'autorelease: pending',
+          describe: 'label to remove from release PR',
+        })
+        .option('release-type', {
+          describe: 'what type of repo is a release being created for?',
+          choices: getReleaserNames(),
+          default: 'node',
+        })
+        .option('path', {
+          describe: 'release from path other than root directory',
+          type: 'string',
+        });
+    },
+    async (argv: GitHubReleaseOptions & yargs.Arguments) => {
+      await main(argv, 'github-release').catch(e => handleError(e, argv));
+    }
+  )
+  .middleware(_argv => {
+    const argv = _argv as GitHubReleaseOptions;
+    // allow secrets to be loaded from file path
+    // rather than being passed directly to the bin.
+    if (argv.token) argv.token = coerceOption(argv.token);
+    if (argv.apiUrl) argv.apiUrl = coerceOption(argv.apiUrl);
+    if (argv.proxyKey) argv.proxyKey = coerceOption(argv.proxyKey);
+  })
+  .option('token', {describe: 'GitHub token with repo write permissions'})
+  .option('release-as', {
+    describe: 'override the semantically determined release version',
+    type: 'string',
+  })
+  .option('release-type', {
+    describe: 'what type of repo is a release being created for?',
+    choices: getReleaserNames(),
+    default: 'node',
+  })
+  .option('bump-minor-pre-major', {
+    describe:
+      'should we bump the semver minor prior to the first major release',
+    default: false,
+    type: 'boolean',
+  })
+  .option('api-url', {
+    describe: 'URL to use when making API requests',
+    default: 'https://api.github.com',
+    type: 'string',
+  })
+  .option('proxy-key', {
+    describe: 'key used by some GitHub proxies',
+    type: 'string',
+  })
+  .option('debug', {
+    describe: 'print verbose errors (use only for local debugging).',
+    default: false,
+    type: 'boolean',
+  })
+  .option('default-branch', {
+    describe: '',
+    type: 'string',
+  })
+  .demandCommand(1)
+  .strict(true);
+
+// The errors returned by octokit currently contain the
+// request object, this contains information we don't want to
+// leak. For this reason, we capture exceptions and print
+// a less verbose error message (run with --debug to output
+// the request object, don't do this in CI/CD).
+export function handleError(err: ErrorObject, argv: yargs.Arguments) {
+  let status = '';
+  const command = argv._.length === 0 ? '' : argv._[0];
+  if (err.status) {
+    status = '' + err.status;
+  }
+  console.error(
+    chalk.red(
+      `command ${command} failed${status ? ` with status ${status}` : ''}`
+    )
+  );
+  if (argv.debug) {
+    console.error('---------');
+    console.error(err.stack);
+  }
+  process.exitCode = 1;
+}