feat: add Danger-JS (#625)

* Add DANGER!

Co-authored-by: Bruno Garcia <[email protected]>

Author: lucas-zimerman

.github/workflows/changelog.yaml

@@ -0,0 +1,15 @@
+name: "Danger"
+on:
+  pull_request:
+    types: [opened, synchronize, reopened, edited, ready_for_review]
+
+jobs:
+  build:
+    name: Changelogs
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v2
+      - uses: actions/setup-node@v1
+      - run: npx [email protected] ci
+        env:
+          GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}

.github/workflows/danger.yml

@@ -0,0 +1,73 @@
+const PR_NUMBER = danger.github.pr.number;
+const PR_URL = danger.github.pr.html_url;
+const PR_LINK = `[#${PR_NUMBER}](${PR_URL})`;
+
+function getCleanTitle() {
+  const title = danger.github.pr.title;
+  return title.split(": ").slice(-1)[0].trim().replace(/\.+$/, "");
+}
+
+function getChangelogDetails() {
+  return `
+<details>
+<summary><b>Instructions and example for changelog</b></summary>
+
+Please add an entry to \`CHANGELOG.md\` to the "Unreleased" section under the following heading:
+ 1. **Feat**: For new user-visible functionality.
+ 2. **Fix**: For user-visible bug fixes.
+ 3. **Ref**: For features, refactory and bug fixes in internal operation.
+
+To the changelog entry, please add a link to this PR (consider a more descriptive message):
+
+\`\`\`md
+- ${getCleanTitle()}. (${PR_LINK})
+\`\`\`
+
+If none of the above apply, you can opt out by adding _#skip-changelog_ to the PR description.
+
+</details>
+`;
+}
+
+async function containsChangelog(path) {
+  const contents = await danger.github.utils.fileContents(path);
+  return contents.includes(PR_LINK);
+}
+
+async function checkChangelog() {
+  const skipChangelog =
+    danger.github && (danger.github.pr.body + "").includes("#skip-changelog");
+
+  if (skipChangelog) {
+    return;
+  }
+
+  const hasChangelog = await containsChangelog("CHANGELOG.md");
+
+  if (!hasChangelog) {
+    fail("Please consider adding a changelog entry for the next release.");
+    markdown(getChangelogDetails());
+  }
+}
+
+async function checkIfFeature() {
+   const title = danger.github.pr.title;
+   if(title.startsWith('feat:')){
+     message('Do not forget to update <a href="https://github.com/getsentry/sentry-docs">Sentry-docs</a> with your feature once the pull request gets approved.');
+   }
+  
+}
+
+async function checkAll() {
+  // See: https://spectrum.chat/danger/javascript/support-for-github-draft-prs~82948576-ce84-40e7-a043-7675e5bf5690
+  const isDraft = danger.github.pr.mergeable_state === "draft";
+
+  if (isDraft) {
+    return;
+  }
+
+  await checkIfFeature();
+  await checkChangelog();
+}
+
+schedule(checkAll);