Feature request: add limit on persistent coverage information

We’re running OpenCover and ReportGenerator on each PR and the amount of data is growing to a point it takes a minute plus to parse historical coverage info supplied via -historydir argument.

I propose a set of new arguments that limits how may items are loaded: -historymax:<maximum items to read> -prunehistory:<true|false> – if true, limit file count in historydir to historymax, keep newest

I can write the code change and PR back to this repository but would love to get some information on whether this makes sense or any alternative approach that I should write instead.

[danielpalme]

@jatouma: The setting only applies to the number of files that get parsed. When generating the HTML report always a maximum of 100 points in the chart gets rendered.

Why does this make sense?! There are two reasons:

• A chart with (many) more points in not readable any more, that’s why a fixed limit exists here
• Parsing more files can make sense if you perform many build with little changes. The charts only contain points when there was a change in:
  • number of covered/total lines
  • number of covered/total branches

[jatouma]

I have not been able to increase the 100 files limit. I have tried changing the value in the config file to 300, but my history report still shows 100 only. Does ReportGenerator not support increasing that maximum value? From skimming through the code, seems like this should work.