Update branch protections

Thanks to https://github.com/gr2m/octokit-plugin-rename-branch
for the graphql mutation + code required to do this

Resolves #4

Author: mheap

README.md

@@ -11,6 +11,7 @@ For each repo, this tool will:
 - Update the default branch for the repo
 - Delete the old branch
 - Update [known URL patterns](https://github.com/mheap/github-default-branch/blob/main/src/update-content.js) in source files
+- Update any branch protections for `$old` to `$new`. (This does **not** work with patterns, it has to be an exact match)
 
 ## Installation
 

bin/github-default-branch

@@ -39,6 +39,7 @@
   const createBranch = require("../src/create-branch");
   const removeBranch = require("../src/remove-branch");
   const updateContent = require("../src/update-content");
+  const updateBranchProtection = require("../src/branch-protection");
 
   const old = argv.old || "master";
   const target = argv.new || "main";
@@ -144,6 +145,14 @@
       });
     }
 
+    if (argv.verbose) {
+      console.log(`✏️  Changing branch protections`);
+    }
+
+    if (!isDryRun) {
+      await updateBranchProtection(owner, repo, old, target, octokit);
+    }
+
     if (argv.verbose) {
       console.log(`✏️  Deleting old branch [${old}] in ${repo}`);
     }

src/branch-protection.js

@@ -0,0 +1,35 @@
+module.exports = async function (owner, repo, old, target, octokit) {
+  // Via https://github.com/gr2m/octokit-plugin-rename-branch/blob/5d3c37439515db9f49f049e28510dc596982cb02/src/rename-branch.ts#L56-L90
+  const query = `query($owner: String!, $repo: String!) {
+        repository(owner:$owner,name:$repo) {
+          branchProtectionRules(first:100) {
+            nodes {
+              id
+              pattern
+            }
+          }
+        }
+      }`;
+  const {
+    repository: {
+      branchProtectionRules: { nodes: branchProtectionRules },
+    },
+  } = await octokit.graphql(query, { owner, repo });
+
+  // there can only be one protection per pattern
+  const { id } = branchProtectionRules.find((rule) => rule.pattern === old);
+  await octokit.graphql(
+    `mutation($branchProtectionRuleId:ID!,$pattern:String!) {
+          updateBranchProtectionRule (input:{branchProtectionRuleId:$branchProtectionRuleId,pattern:$pattern}) {
+            branchProtectionRule {
+              id,
+              pattern
+            }
+          }
+        }`,
+    {
+      branchProtectionRuleId: id,
+      pattern: target,
+    }
+  );
+};