FileTarget - Archive should not fail when ArchiveFileName matches FileName

[snakefoot]

Attempt to fix the following build error, and also resolve this issue #1707

https://ci.appveyor.com/project/nlog/nlog/build/4.4.4171

Was able to reproduce the bug locally, and it seems the following happens:

The test uses ArchiveEvery = FileArchivePeriod.Minute and FileName = ${date:format=yyyyMMddHHmmssfff}.txt. It sleeps 50 ms between each LogEvent to ensure that each LogEvent get their own file.

If the test is executed at exact 12:59:59.999 then it will trigger an extra unexpected archive operation. As one of LogEvent timestamps will then be one-minute older than the creation-time of the previous log-file.

The archive operation fails because the log-filename (based on current-time) and the generated archive-filename (based on file-write-time) becomes the same. Because the archive-filename already exists then it attempts to append the contents of the log-filename to the archive-filename and it of course fails.

We could change the ArchiveEvery to Year for the test DeleteArchiveFilesByDateWithDateName, and then it would only fail at new years eve.

We could also consider to change FileTarget.ArchiveFile() to check if fileName and archiveFileName is the same, and if so then just do nothing but doing a InternalLogger.Info()

---

This change is 

[304NotModified]

Great work! \o/

[304NotModified]

Is this change of test still needed?

[snakefoot]

Well the test is not depending on FileArchivePeriod.Minutes, so no need to introduce more random behavior than needed.

Added a new test that exercises the new code.

[codecov-io]

Current coverage is 81% (diff: 100%)

Merging #1886 into master will decrease coverage by <1%

@@             master      #1886   diff @@
==========================================
  Files           276        276          
  Lines         18636      18640     +4   
  Methods        2861       2861          
  Messages          0          0          
  Branches       2139       2140     +1   
==========================================
- Hits          15160      15157     -3   
- Misses         2971       2978     +7   
  Partials        505        505          

Powered by Codecov. Last update f3f9643...5fdc97e

[304NotModified]

Reviewed 2 of 2 files at r1.
Review status: all files reviewed at latest revision, all discussions resolved.

---

Comments from Reviewable

[304NotModified]

merged :)

[owerkop]

So is the warning still valid:
"Warning: when deleting archives files is enabled (e.g. maxArchiveFiles ), the folder of the archives should different than the log files. Otherwise, all content, not just logs, in the folder that is not log archives from the target will be deleted."
(https://github.com/nlog/NLog/wiki/File-target )
?

[snakefoot]

No this was fixed with NLog 4.5, but for NLog 4.4.13 (or older) then the advice is still valid.

[snakefoot]

@owerkop Have updated the Wiki for FileTarget about warning only being relevant for NLog 4.4.13 (and older)

[304NotModified]

Looks great @snakefoot , thanks! (And valid question @owerkop. Also thanks for that!)