In a way I'm honestly surprised we've gotten that high, but on the other hand maybe it's not too crazy either: Kiesel engine (written in Zig) is at 75% and is pretty much the same age as Nova, and I believe has a similar sized "development team" (one person doing a lot of the work, LinusG for them and me on Nova's side, and then a smattering of other people with a bit less free time on their hands).
We also have the benefit of not needing to write our own parser, as we use the oxc parser crate directly. That has given us a huge leg up in getting up and running.
That being said, our own tests show 70.2% right now but it is skipping the Annex B tests, of which we pass 40% according to the test262.fyi website. And on test262.fyi we currently pass only 58.7%: this number is in error I believe. We've already passed 60% on test262.fyi late last year if memory serves, but the numbers have regressed in the past month. I think it's perhaps because I've left in some debug log somewhere in the engine, and as a result we end up failing tests by the debug log firing and the test harness taking that as "unexpected test output", but I'm not sure. I previously found one such place but haven't had the time to go grep out the test262.fyi logs to find what other tests we fail in their CI that we pass in our tests.
But, an apology is also in order: the 70% number on our website is more misleading than I thought it is. Our test runner skips entirely Annex B[1] _and_ Intl tests; one could perhaps view the 70% number then as "percentage of ECMA262 specification done". The 58% value reported by test262.fyi is probably the correct value (unless we have a bug with debug prints that causes spurious failures there).
[1]: I remembered that we skip Annex B tests; those are fairly few in number and we pass 40% of them anyway, so their effect isn't large. Didn't remember the other category we skip, and absolutely didn't remember that it's a major one like Intl.
In a way I'm honestly surprised we've gotten that high, but on the other hand maybe it's not too crazy either: Kiesel engine (written in Zig) is at 75% and is pretty much the same age as Nova, and I believe has a similar sized "development team" (one person doing a lot of the work, LinusG for them and me on Nova's side, and then a smattering of other people with a bit less free time on their hands).
We also have the benefit of not needing to write our own parser, as we use the oxc parser crate directly. That has given us a huge leg up in getting up and running.
That being said, our own tests show 70.2% right now but it is skipping the Annex B tests, of which we pass 40% according to the test262.fyi website. And on test262.fyi we currently pass only 58.7%: this number is in error I believe. We've already passed 60% on test262.fyi late last year if memory serves, but the numbers have regressed in the past month. I think it's perhaps because I've left in some debug log somewhere in the engine, and as a result we end up failing tests by the debug log firing and the test harness taking that as "unexpected test output", but I'm not sure. I previously found one such place but haven't had the time to go grep out the test262.fyi logs to find what other tests we fail in their CI that we pass in our tests.