Quick Greasemonkey/Tampermonkey script for GitHub PRs: disable merge button until certain checks are met. Looks at branch naming pattern, tags, automatic tests. Highlights what it found.

Github PR Merge - checks and highlights.js

// ==UserScript==
// @name        GitHub disable merge button until certain checks are met
// @description Looks at branch naming pattern, tags, automatic tests. Highlights what it found.
// @author      github/tdbe
// @version     1
// @match       *github.com/*/pull/*
// @run-at      document-idle
// @connect     github.com
// @connect     githubusercontent.com
// @grant       GM_notification
// @grant       GM_setValue
// @grant       GM_getValue
// @grant       GM_addStyle
// ==/UserScript==

(function() {
    'use strict';

    function doChecks(mergeButtons){
		for (let i = 0; i < mergeButtons.length; i++) {
			mergeButtons[i].style.backgroundColor = "yellow";// set all merge buttons to magenta so we know the greasemonkey is active on this page
			mergeButtons[i].disabled = true;// disable just for safety
		}


		//checks:
		var passed = true;

		// check title:
		// <bdi class="js-issue-title markdown-title">
		var elems = document.getElementsByClassName("js-issue-title");
		for (var i=0; i<elems.length; ++i) {
			if(elems[i].classList.contains("markdown-title")){
				// check if title starts with correct prefix:
				if(!elems[i].innerHTML.includes("[")){
					passed = false;
                    elems[i].style.outline = "red dashed 3px";
				}
                else{
                    elems[i].style.outline = "#d35ed3 dashed 3px";
                }
			}
		}

		// check tags:
		// <a id="label-209d8e" href="..../QA%20OK" data-name="QA OK"
		// <a id="label-f89fb1" href="..../Review%20OK" data-name="Review OK"
		//elems = document.getElementsByTagName("a");
		elems = document.getElementsByClassName("IssueLabel");
		for (i=0; i<elems.length; ++i) {
				// check for blocking tags:
				var attr = elems[i].getAttribute("data-name");
				if(attr == "Needs QA" || attr == "QA WIP" || attr == "Needs Review"){
					passed = false;
                    elems[i].style.fontSize = "2em";
                    elems[i].style.outline = "red dashed 3px";
				}
		}

        // check if status says "All checks have pased"
		elems = document.getElementsByClassName("status-heading");
		var found = false;
		for (i=0; i<elems.length; ++i) {
			if(elems[i].innerHTML.startsWith("All checks have passed")){
				found = true;
			}
		}
		if(found == false){
			passed = false;
            for (i=0; i<elems.length; ++i) {
			    elems[i].style.fontSize = "3em";
                elems[i].style.outline = "red dashed 3px";
		    }
		}
        else{
            for (i=0; i<elems.length; ++i) {
			    elems[i].style.fontSize = "3em";
                elems[i].style.outline = "#d35ed3 dashed 3px";
		    }
        }

		if(!passed){
			for (let i = 0; i < mergeButtons.length; i++) {
				mergeButtons[i].style.backgroundColor = "#b53131";// set all merge buttons to red so we know the greasemonkey is active on this page
                mergeButtons[i].style.outline = "red dashed 3px";
				mergeButtons[i].disabled = true;
			}
		}
		else{// PASSED, or, error conditions not found, so set it to magenta.
			for (let i = 0; i < mergeButtons.length; i++) {
				mergeButtons[i].style.backgroundColor = "#d35ed3";// set all merge buttons to magenta so we know the greasemonkey is active on this page
				mergeButtons[i].style.outline = "#d35ed3 dashed 3px";
                mergeButtons[i].disabled = false;
			}
		}
    }

    function run(withRetries){
		var states = document.getElementsByClassName("State--open");
		if(states.length == 0){
			return;
		}

		// also mark the "Wants to merge" line to check source branch and dest branch
		var srcDest = document.getElementsByClassName("commit-ref-dropdown")[0].parentNode;
		srcDest.style.outline = "yellow dashed 8px";


		var mergeButtons = document.getElementsByClassName("merge-box-button");

        if(withRetries){
		    var i = 0;
		    var intr = setInterval(function() {
			    mergeButtons = document.getElementsByClassName("merge-box-button");
			    if (++i == 10 || mergeButtons.length!= 0) clearInterval(intr);

		    	//if(mergeButtons.length == 0){
		    	//	alert("Could not find mergeButtons: "+mergeButtons.length);
		    	//}

			    doChecks(mergeButtons);

		    }, 1000)
        }
        else{
            doChecks(mergeButtons);
        }
    }

    run(true);

    let prevScrollPos = 0;
    let scrollPos = 0;
    let delta = 100;
    let ticking = false;

    function doSomething(scrollPos) {
        if(scrollPos-prevScrollPos>delta){
            run(false);
            prevScrollPos = scrollPos;
        }
    }

    document.addEventListener("scroll", (event) => {
      scrollPos = window.scrollY;

      if (!ticking) {
          window.requestAnimationFrame(() => {
          doSomething(scrollPos);
          ticking = false;
        });

        ticking = true;
      }
    });
})();