feat(snippet-bot): require the config file to enable the bot

packages/snippet-bot/README.md

@@ -2,7 +2,9 @@
 
 Instructions are provided in [googleapis/repo-automation-bots](https://github.com/googleapis/repo-automation-bots/blob/master/README.md) for deploying and testing your bots.
 
-This bot needs read/write permissions on PRs and Checks.
+This bot needs read/write permissions on PRs and Checks. Also make sure that the bot is listening to webhooks for PRs.
+
+After installing the bot, you have to have `.github/snippet-bot.yml` for actually enabling it.
 
 This bot uses nock for mocking requests to GitHub, and snap-shot-it for capturing responses; This allows updates to the API surface to be treated as a visual diff, rather than tediously asserting against each field.
 

packages/snippet-bot/__snapshots__/snippet-bot.js

@@ -10,20 +10,6 @@ exports['snippet-bot responds to PR sets a "failure" context on PR 1'] = {
   },
 };
 
-exports[
-  'snippet-bot responds to PR sets a "failure" context on PR even when it failed to read the config 1'
-] = {
-  name: 'Mismatched region tag',
-  conclusion: 'failure',
-  head_sha: 'ce03c1b7977aadefb5f6afc09901f106ee6ece6a',
-  output: {
-    title: 'Mismatched region tag detected.',
-    summary: 'Some new files have mismatched region tag',
-    text:
-      "test.py:5, tag `hello` has already started\ntest.py:10, tag `lol` doesn't have a matching start tag\ntest.py:8, tag `world` doesn't have a matching end tag",
-  },
-};
-
 exports[
   'snippet-bot responds to PR sets a "success" context on PR by ignoreFile 1'
 ] = {

packages/snippet-bot/src/snippet-bot.ts

@@ -58,21 +58,28 @@ class Configuration {
 
 export = (app: Application) => {
   app.on('pull_request', async context => {
+    const repoUrl = context.payload.repository.full_name;
     let configOptions!: ConfigurationOptions | null;
     try {
-      configOptions = await context.config(
-        CONFIGURATION_FILE_PATH,
-        DEFAULT_CONFIGURATION
+      configOptions = await context.config<ConfigurationOptions>(
+        CONFIGURATION_FILE_PATH
       );
     } catch (err) {
       err.message = `Error reading configuration: ${err.message}`;
       logger.error(err);
-      // Falling back to default.
-      configOptions = DEFAULT_CONFIGURATION;
+      // Now this bot is only enabled if it finds the configuration file.
+      // Exiting.
+      return;
     }
-    const configuration = new Configuration(
-      configOptions as ConfigurationOptions
-    );
+
+    if (configOptions === null) {
+      logger.info(`snippet-bot is not configured for ${repoUrl}.`);
+      return;
+    }
+    const configuration = new Configuration({
+      ...DEFAULT_CONFIGURATION,
+      ...configOptions,
+    });
     logger.info({config: configuration});
 
     // List pull request files for the given PR

packages/snippet-bot/test/snippet-bot.ts

@@ -110,28 +110,15 @@ describe('snippet-bot', () => {
       requests.done();
     });
 
-    it('sets a "failure" context on PR even when it failed to read the config', async () => {
+    it('exits early when it failed to read the config', async () => {
       // eslint-disable-next-line @typescript-eslint/no-var-requires
-      const changedFiles = require(resolve(fixturesPath, './pr_files_added'));
       const payload = require(resolve(fixturesPath, './pr_event'));
-      const blob = require(resolve(fixturesPath, './failure_blob'));
 
       const requests = nock('https://api.github.com')
         .get(
           '/repos/tmatsuo/repo-automation-bots/contents/.github/snippet-bot.yml'
         )
-        .reply(403, {content: 'Permission denied'})
-        .get('/repos/tmatsuo/repo-automation-bots/pulls/14/files?per_page=100')
-        .reply(200, changedFiles)
-        .get(
-          '/repos/tmatsuo/repo-automation-bots/git/blobs/223828dbd668486411b475665ab60855ba9898f3'
-        )
-        .reply(200, blob)
-        .post('/repos/tmatsuo/repo-automation-bots/check-runs', body => {
-          snapshot(body);
-          return true;
-        })
-        .reply(200);
+        .reply(403, {content: 'Permission denied'});
 
       await probot.receive({
         name: 'pull_request',
@@ -199,5 +186,27 @@ describe('snippet-bot', () => {
 
       requests.done();
     });
+
+    it('quits early if there is no config file', async () => {
+      // eslint-disable-next-line @typescript-eslint/no-var-requires
+      const payload = require(resolve(fixturesPath, './pr_event'));
+
+      // probot tries to fetch the org's config too.
+      const requests = nock('https://api.github.com')
+        .get(
+          '/repos/tmatsuo/repo-automation-bots/contents/.github/snippet-bot.yml'
+        )
+        .reply(404, {content: 'Not Found'})
+        .get('/repos/tmatsuo/.github/contents/.github/snippet-bot.yml')
+        .reply(404, {content: 'Not Found'});
+
+      await probot.receive({
+        name: 'pull_request',
+        payload,
+        id: 'abc123',
+      });
+
+      requests.done();
+    });
   });
 });