Truncation of full web results makes them less useful

[curiouskiwi]

For example, in the Filter problem, the full results web page always showed the entire results

This allows the student to see all the values and get a better grasp of where their program may be failing (which pixel, location, etc).

The new v4 truncates the full results, which then takes away any advantage of actually loading the full results page.

Can we continue to show the full results on the web page? Or, perhaps have a setting that can be set in the particular checks for a problem for those that need this extra info?

[rongxin-liu]

There are cases where a student’s output is considerably large due to a bug, which would crash check50 at rendering time. How can we account for those scenarios?

Perhaps we should impose a maximum truncation length for that.

The new truncation approach always shows the first diff it finds.

[curiouskiwi]

Could the max truncation simply be the length of the expected output? The log itself is showing the entire expected output, but the student never sees their actual output in order to match it up. This may only affect this particular problem, which is why I thought a "per problem" override truncation setting may be the best way to approach it.

[bolt-blue]

Setting some acceptable limit (max output before truncation occurs) is totally reasonable.
At this moment, I'd say whatever is simplest to implement that also gives the user more information.
Even if it was e.g. 30 lines (any value that is a little larger than actual output of any of the check50 tests), that would also immediately communicate when there's a bug that's causing more output than expected.

[Makaze]

I agree with bolt.

A truncation limit of, say, 30 lines or 500 characters seems reasonable.

Here are some examples where the new output format is near useless (Various bugs in pizza.py exercise):

https://submit.cs50.io/check50/531ca1e0cfcc6b403c5df47827fba169271c5a26
https://submit.cs50.io/check50/00db57bec59ec17a29330164f746b97cd5f83a2c

[ivanharvard]

You can use the check50.config class to modify this.

If you want to turn off dynamic truncation for this specific check file, the checkwriter can write:

import check50

check50.config.set_dynamic_truncate(False)

This is the default truncation behavior of v3.4.0.

Otherwise, you can just set the truncation length (in num. of chars) to be whatever integer value that you'd like (default is 30).

import check50

check50.config.set_truncate_len(9999)

The only issue with this is that as you increase the truncate_len, you increase the console output. Perhaps we can modify truncate_len to take in a dictionary like this instead:

check50.config.set_truncate_len({"ansi": 30, "html": 999})

Or make a new variable for each one:

check50.config.set_ansi_truncate_len(30)
check50.config.set_html_truncate_len(999)

Or we can leave it as it is now.

Semi-related, we might also want to add an escape_control_chars config setting, so \n shows up as actual newlines, as opposed to \\n.