utility for knowing what other branches will be merged if you merge a git branch into another

git-sim-merge

#!/usr/bin/env node

var br1 = process.argv[2];
var br2 = process.argv[3];

var exec = require('child_process').exec;

function setDiff(s1, s2){
  return s1.filter(function(e){
    return s2.indexOf(e) < 0;
  });
}

function parseBranches(stdout){
  return stdout.split(/[\r\n\s\*]+/).filter(function(brName){
    return brName !== '';
  });
}

function p_mergedIn(br){
  return new Promise(function(res, rej){
    exec('git branch --merged ' + br, function(err, stdout, stderr){
      if(err){
        rej(err);
      } else {
        res(stdout);
      }
    });
  }).then(parseBranches);
}

function printSet(s){
  s.sort().forEach(function(e){
    console.log(e);
  })
}

Promise.all([p_mergedIn(br1),p_mergedIn(br2)]).then(function(arr){
  return (function(branches1, branches2){
    return setDiff(branches1, branches2);
  }).apply(null, arr)
}).then(printSet);