Overhaul core Tracker: add units tests to the new `tracker-core` package

[josecelano]

Parent issue: #1181

After extracting the new package I want to review the tests. We had a lot of high-level tests because It was very hard to unit test the old core::Tracker. Now it should be easier to write unit tests for the package.

Sub-tasks

• Overhaul core Tracker: add tests for authentication mod #1231
• Overhaul core Tracker: add tests for whitelist mod #1235
• Overhaul core Tracker: add tests for torrent mod #1240
• Overhaul core Tracker: add tests for announce_handler mod #1247
• Overhaul core Tracker: add tests for scrape_handler mod #1249
• Overhaul core Tracker: add tests for error mod #1250
• Overhaul core Tracker: add tests for databases mod #1251

[josecelano]

The code coverage report for only the bittorrent-tracker-core package:

cargo llvm-cov --package bittorrent-tracker-core

The current state before starting adding tests:

Filename                                                                    Functions  Missed Functions  Executed       Lines      Missed Lines     Cover    Branches   Missed Branches     Cover
---------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------
packages/tracker-core/src/announce_handler.rs                                      32                 2    93.75%         380                15    96.05%           0                 0         -
packages/tracker-core/src/authentication/handler.rs                                28                 1    96.43%         203                35    82.76%           0                 0         -
packages/tracker-core/src/authentication/key/mod.rs                                18                 3    83.33%         124                12    90.32%           0                 0         -
packages/tracker-core/src/authentication/key/repository/in_memory.rs               10                 2    80.00%          25                 5    80.00%           0                 0         -
packages/tracker-core/src/authentication/key/repository/persisted.rs                4                 0   100.00%          17                 0   100.00%           0                 0         -
packages/tracker-core/src/authentication/mod.rs                                    19                 0   100.00%         201                 0   100.00%           0                 0         -
packages/tracker-core/src/authentication/service.rs                                 9                 0   100.00%          53                 2    96.23%           0                 0         -
packages/tracker-core/src/core_tests.rs                                             9                 0   100.00%          62                 0   100.00%           0                 0         -
packages/tracker-core/src/databases/driver.rs                                       1                 0   100.00%           9                 2    77.78%           0                 0         -
packages/tracker-core/src/databases/error.rs                                        4                 4     0.00%          31                31     0.00%           0                 0         -
packages/tracker-core/src/databases/mod.rs                                          2                 0   100.00%           6                 0   100.00%           0                 0         -
packages/tracker-core/src/databases/mysql.rs                                       31                31     0.00%         189               189     0.00%           0                 0         -
packages/tracker-core/src/databases/setup.rs                                        1                 0   100.00%           6                 1    83.33%           0                 0         -
packages/tracker-core/src/databases/sqlite.rs                                      34                18    47.06%         208                81    61.06%           0                 0         -
packages/tracker-core/src/error.rs                                                  1                 1     0.00%           5                 5     0.00%           0                 0         -
packages/tracker-core/src/lib.rs                                                    7                 0   100.00%         120                 0   100.00%           0                 0         -
packages/tracker-core/src/peer_tests.rs                                             1                 0   100.00%          35                 0   100.00%           0                 0         -
packages/tracker-core/src/scrape_handler.rs                                         8                 0   100.00%          83                 0   100.00%           0                 0         -
packages/tracker-core/src/torrent/manager.rs                                        3                 1    66.67%          28                11    60.71%           0                 0         -
packages/tracker-core/src/torrent/repository/in_memory.rs                          27                 2    92.59%         298                 9    96.98%           0                 0         -
packages/tracker-core/src/torrent/repository/persisted.rs                           3                 0   100.00%          11                 0   100.00%           0                 0         -
packages/tracker-core/src/torrent/services.rs                                      20                 2    90.00%         323                14    95.67%           0                 0         -
packages/tracker-core/src/whitelist/authorization.rs                                8                 0   100.00%          46                 0   100.00%           0                 0         -
packages/tracker-core/src/whitelist/manager.rs                                     21                 3    85.71%         113                 7    93.81%           0                 0         -
packages/tracker-core/src/whitelist/mod.rs                                          4                 0   100.00%          33                 0   100.00%           0                 0         -
packages/tracker-core/src/whitelist/repository/in_memory.rs                        16                 0   100.00%          85                 0   100.00%           0                 0         -
packages/tracker-core/src/whitelist/repository/persisted.rs                         4                 0   100.00%          24                 2    91.67%           0                 0         -
packages/tracker-core/src/whitelist/setup.rs                                        1                 0   100.00%           7                 0   100.00%           0                 0         -
packages/tracker-core/src/whitelist/whitelist_tests.rs                              2                 0   100.00%          11                 0   100.00%           0                 0         -

I will add more unit tests to the package.