endSuite hook is called without matching startSuite hook

[RedX2501]

I'm creating this ticket due to ticket webdriverio/webdriverio#13013

The summary of the linked issue is that endSuite might be called without a matching startSuite if a describe is used that has no tests. This can happen when dynamically generating its.

I'm not sure if it is strictly necessary for hooks to always be called pairwise (start + end) but it makes coding any state dependent hooks much easier.

Here is the diff that solved my problem:

diff --git a/node_modules/mocha/lib/runner.js b/node_modules/mocha/lib/runner.js
index 60a19f0..9103d9b 100644
--- a/node_modules/mocha/lib/runner.js
+++ b/node_modules/mocha/lib/runner.js
@@ -854,14 +854,13 @@ Runner.prototype.runSuite = function (suite, fn) {
   var total = this.grepTotal(suite);
 
   debug('runSuite(): running %s', suite.fullTitle());
+  this.emit(constants.EVENT_SUITE_BEGIN, (this.suite = suite));
 
   if (!total || (self.failures && suite._bail)) {
     debug('runSuite(): bailing');
     return fn();
   }
 
-  this.emit(constants.EVENT_SUITE_BEGIN, (this.suite = suite));
-
   function next(errSuite) {
     if (errSuite) {
       // current suite failed on a hook from errSuite
@@ -903,6 +902,7 @@ Runner.prototype.runSuite = function (suite, fn) {
     // remove reference to test
     delete self.test;
 
+    debug('done(): ending %s', suite.fullTitle());
     self.hook(HOOK_TYPE_AFTER_ALL, function () {
       self.emit(constants.EVENT_SUITE_END, suite);
       fn(errSuite);

This issue body was partially generated by patch-package.

[JoshuaKGoldberg]

Interesting find! Could you / someone please post an isolated reproduction we can take a look at here? One that doesn't require knowing other downstream tools like webdriverio. Thanks!

https://antfu.me/posts/why-reproductions-are-required

[JoshuaKGoldberg]

Ping @RedX2501 - any chance you could post an isolated reproduction please?