chore: Add reviewable config; rename release workflow to draft.

Author: iphydf

.github/workflows/release.yml .github/workflows/draft.yml

@@ -1,4 +1,4 @@
-name: release
+name: draft
 
 on:
   push:
@@ -7,6 +7,11 @@ on:
     branches: [master]
     types: [opened, reopened, synchronize]
 
+# Cancel old builds when pushing new commits.
+concurrency:
+  group: draft-${{ github.event.pull_request.number || github.ref }}
+  cancel-in-progress: true
+
 jobs:
   release:
     uses: TokTok/ci-tools/.github/workflows/release-drafter.yml@master

.reviewable/completion.js

@@ -0,0 +1,76 @@
+// jshint esversion: 6
+
+// This code will check that the pull request has been approved via GitHub
+// review approval by a minimum number of reviewers and by all assignees, and
+// that no changes were requested by any reviewers.  Only reviewers with write
+// access to the repository are considered.
+//
+// This is very similar to GitHub's built-in branch protection option to require
+// pull request reviews before merging, but allows for much more flexibility and
+// customization.
+
+// dependencies: lodash4
+
+// Helper function to check if a user is a bot.
+function isBotAuthor(author) {
+  return (
+    author.username.endsWith("[bot]") || author.username.startsWith("toktok-")
+  );
+}
+
+function equals(a) {
+  return (b) => a === b;
+}
+
+// The number of approvals required to merge: at least 2 humans must approve the
+// code. If the author is a bot, then 2 approvals are required; otherwise, only
+// 1 approval is required (because 1 human wrote the code, so they approve).
+let numApprovalsRequired = isBotAuthor(review.pullRequest.author) ? 2 : 1;
+
+const approvals = review.pullRequest.approvals;
+
+let numApprovals = _.filter(approvals, equals("approved")).length;
+const numRejections = _.filter(approvals, equals("changes_requested")).length;
+
+const discussionBlockers = _(review.discussions)
+  .filter((x) => !x.resolved)
+  .flatMap("participants")
+  .filter((x) => !x.resolved)
+  .map((user) => _.pick(user, "username"))
+  .value();
+
+let pendingReviewers = _(discussionBlockers)
+  .map((user) => _.pick(user, "username"))
+  .concat(review.pullRequest.requestedReviewers)
+  .value();
+
+const required = _.map(review.pullRequest.assignees, "username");
+_.pull(required, review.pullRequest.author.username);
+if (required.length) {
+  numApprovalsRequired = _.max([required.length, numApprovalsRequired]);
+  numApprovals =
+    _(approvals).pick(required).filter(equals("approved")).size() +
+    _.min([numApprovals, numApprovalsRequired - required.length]);
+  pendingReviewers = _(required)
+    .reject((username) => approvals[username] === "approved")
+    .reject((username) => pendingReviewers.length && approvals[username])
+    .map((username) => ({ username }))
+    .concat(pendingReviewers)
+    .value();
+}
+
+pendingReviewers = _.uniqBy(pendingReviewers, "username");
+
+const description =
+  (numRejections ? `${numRejections} change requests, ` : "") +
+  `${numApprovals} of ${numApprovalsRequired} approvals obtained`;
+const shortDescription =
+  (numRejections ? `${numRejections} ✗, ` : "") +
+  `${numApprovals} of ${numApprovalsRequired} ✓`;
+
+return {
+  completed: numApprovals >= numApprovalsRequired,
+  description,
+  shortDescription,
+  pendingReviewers,
+};

.reviewable/settings.yaml

@@ -0,0 +1,4 @@
+# Reviewable settings file. Read the docs at https://docs.reviewable.io/repositories.html#store-repository-settings-using-the-reviewable-directory
+approval-text: ":lgtm_strong:"
+github-status:
+  updates: always