ci: prioritize labelling pull requests based on their title rather than their commits

dangerfile.ts

@@ -6,16 +6,20 @@ if (danger.github.pr.body.length === 0) {
   fail('Please include a body for your PR');
 }
 
-const createOrAddLabelSafely = async (name: string, color: string) => {
+const createOrAddLabelSafely = async (name: string, color: string): boolean => {
   try {
     await danger.github.utils.createOrAddLabel({
       name,
       color: color.replace('#', ''),
       description: '',
     });
+
+    return true;
   } catch (error) {
     console.warn(error);
     warn(`Was unable to create or add label "${name}"`);
+
+    return false;
   }
 };
 
@@ -39,6 +43,18 @@ const labelBasedOnRules = async () => {
   );
 };
 
+const labelBasedOnTitle = async (): Promise<boolean> => {
+  if (danger.github.pr.title.startsWith('feat')) {
+    return createOrAddLabelSafely('enhancement', '#84b6eb');
+  }
+
+  if (danger.github.pr.title.startsWith('fix')) {
+    return createOrAddLabelSafely('bug', '#ee0701');
+  }
+
+  return false;
+};
+
 const labelBasedOnCommits = async () => {
   const commits = danger.github.commits.map(commits => commits.commit.message);
 
@@ -51,7 +67,20 @@ const labelBasedOnCommits = async () => {
   }
 };
 
-Promise.all([labelBasedOnRules(), labelBasedOnCommits()]).catch(error => {
-  console.error(error);
-  fail(`Something went very wrong: ${error}`);
-});
+const labelBasedOnTitleOrCommits = async () => {
+  // prioritize labeling based on the title since most pull requests will get
+  // squashed into a single commit with the title as the subject, but fallback
+  // to looking through the commits if we can't determine a label from the title
+  if (await labelBasedOnTitle()) {
+    return;
+  }
+
+  await labelBasedOnCommits();
+};
+
+Promise.all([labelBasedOnRules(), labelBasedOnTitleOrCommits()]).catch(
+  error => {
+    console.error(error);
+    fail(`Something went very wrong: ${error}`);
+  },
+);