feat(land): avoid landing on the wrong default branch (#586)

Fail if the user is trying to land a commit on "master" or "main", and
the default branch name doesn't match.

components/git/land.js

@@ -1,5 +1,6 @@
 'use strict';
 
+const auth = require('../../lib/auth');
 const { parsePRFromURL } = require('../../lib/links');
 const { getMetadata } = require('../metadata');
 const CLI = require('../../lib/cli');
@@ -144,10 +145,9 @@ function land(state, argv) {
   if (argv.yes) {
     cli.setAssumeYes();
   }
-  const req = new Request();
   const dir = process.cwd();
 
-  return runPromise(main(state, argv, cli, req, dir)).catch((err) => {
+  return runPromise(main(state, argv, cli, dir)).catch((err) => {
     if (cli.spinner.enabled) {
       cli.spinner.fail();
     }
@@ -163,10 +163,16 @@ module.exports = {
   handler
 };
 
-async function main(state, argv, cli, req, dir) {
+async function main(state, argv, cli, dir) {
+  const credentials = await auth({
+    github: true
+  });
+  const req = new Request(credentials);
   let session = new LandingSession(cli, req, dir);
 
-  if (state !== AMEND && state !== CONTINUE && session.warnForWrongBranch()) {
+  if (state !== AMEND &&
+      state !== CONTINUE &&
+      await session.warnForWrongBranch()) {
     return;
   }
 

lib/landing_session.js

@@ -456,6 +456,22 @@ class LandingSession extends Session {
   async status() {
     // TODO
   }
+
+  async warnForWrongBranch() {
+    if (super.warnForWrongBranch()) {
+      return true;
+    }
+    const rev = this.getCurrentBranch();
+    const { repository: { defaultBranchRef } } = await this.req.gql(
+      'DefaultBranchRef',
+      { owner: this.owner, repo: this.repo });
+    if ((rev === 'master' || rev === 'main') && defaultBranchRef.name !== rev) {
+      this.cli.warn(`You are running git-node-land on \`${rev}\`,` +
+                    ` but the default branch is \`${defaultBranchRef.name}\`.`);
+      this.cli.setExitCode(1);
+      return true;
+    }
+  }
 }
 
 module.exports = LandingSession;

lib/queries/DefaultBranchRef.gql

@@ -0,0 +1,8 @@
+query DefaultBranchRef($owner: String!, $repo: String!) {
+  repository(owner: $owner, name: $repo) {
+    defaultBranchRef {
+      name
+    }
+  }
+}
+