perf: set own verifyConditons default, no need for npm plugin

Unlike regular `semantic-release`, this library doesn’t interact with
`npm` remotely and verifying `npm` credentials isn’t productive, only a
relatively expensive operation.

README.md

@@ -32,14 +32,14 @@ It helps to think about `semantic-release-github-pr` as a variation on `semantic
 
 A PR gets a comment if:
 
-1. The PR's "from" branch matches the current branch (that this command is being run against).
+1.  The PR's "from" branch matches the current branch (that this command is being run against).
 
-   To cover multiple CI scenarios ([see below](#ci)), either of:
+    To cover multiple CI scenarios ([see below](#ci)), either of:
 
-   1. The PR's [_test_ merge commit](https://developer.github.com/v3/pulls/#response-1) matches the current branch's `git` HEAD.
-   2. The PR and the current branch have the same `git` HEAD.
+    1.  The PR's [_test_ merge commit](https://developer.github.com/v3/pulls/#response-1) matches the current branch's `git` HEAD.
+    2.  The PR and the current branch have the same `git` HEAD.
 
-2. The PR's base branch matches `master` (default) unless the [`githubPr.branch` configuration option](https://github.com/semantic-release/semantic-release#Release-config) is set.
+2.  The PR's base branch matches `master` (default) unless the [`githubPr.branch` configuration option](https://github.com/semantic-release/semantic-release#Release-config) is set.
 
 ## Configuration
 
@@ -115,16 +115,22 @@ Running `semantic-release-github-pr` is equivalent to running `semantic-release`
 ```json
 {
   "release": {
+    "verifyConditions": "@semantic-release/github",
     "analyzeCommits": "semantic-release-github-pr",
     "generateNotes": "semantic-release-github-pr"
   }
 }
 ```
 
+### verifyConditions
+
+The `@semantic-release/github` plugin is set as a default.
+
 #### analyzeCommits
+
 Used as a hook to clean up previous changelog PR comments made by the `generateNotes` plugin, keeping it from flooding a PR with (eventually stale) changelog comments over time.
 
-If `semantic-release` determines that there's no new version, this plugin will also post a "no release" comment on a matching PR. 
+If `semantic-release` determines that there's no new version, this plugin will also post a "no release" comment on a matching PR.
 
 This plugin doesn't actually analyze commits to determine when to make a release, but defers to the plugin it decorates ([`@semantic-release/commit-analyzer`](https://github.com/semantic-release/commit-analyzer/) by default).
 
@@ -136,4 +142,4 @@ Creates a comment on matching PRs with the changelog for the release that would
 
 This plugin doesn't actually generate the changelog that ends up in the PR comment, but defers to the plugin it decorates ([`@semantic-release/release-notes-generator`](https://github.com/semantic-release/release-notes-generator) by default).
 
-See the [`Release config`](#release-config) section for how to configure a custom `generateNotes` plugin and/or set options.
+See the [`Release config`](#release-config) section for how to configure a custom `generateNotes` plugin and/or set options.

bin/semantic-release-github-pr.js

@@ -20,8 +20,13 @@ const { getCurrentBranchName } = require('../src/git-utils');
     // Set `dry-run` to keep `semantic-release` from publishing an actual release.
     `--dry-run`,
     `--branch=${branch}`,
+    // We hard-set our versions of `analyze-commits` and `generate-notes`.
     `--analyze-commits=${plugins}`,
     `--generate-notes=${plugins}`,
+    // We use `extends` here to pick up a soft-set default for `verifyConditions`,
+    // allowing users to override it (setting a plugin directly from the CLI
+    // trumps plugins read from a config file).
+    `--extends=${plugins}`,
   ]);
 
   execa('semantic-release', args, { stdio: 'inherit' });

src/index.js

@@ -77,6 +77,7 @@ const generateNotes = wrapPlugin(
 );
 
 module.exports = {
+  verifyConditions: '@semantic-release/github',
   analyzeCommits: decoratePlugins(analyzeCommits),
   generateNotes: decoratePlugins(generateNotes),
 };