weird warning on unused package

[bobzhang]

git/toml-parser$moon clean
git/toml-parser$moon test 
Warning: [0029]
   ╭─[ /Users/hongbozhang/git/toml-parser/cmd/main/moon.pkg.json:4:5 ]
   │
 4 │     "bobzhang/toml"
   │     ───────┬───────  
   │            ╰───────── Warning: Unused package 'bobzhang/toml'
───╯

There are multiple bugs I found:

1. when I removed cmd/main_test.mbt, the warning is still there, a close look shows that the blackbox test is always there even there is no blackbox test
2. It seems the warning does not follow the running command, I could not reproduce the behavior when I ran moon test --verbose

[lynzrand]

1. We have no reliable way to detect doctests (which are also bb tests) beforehand, thus bb test is built at all times. Duplicate of moon check does not report unused wbtest-import while test-import is reported moonbitlang/moon#1086, I think the unused import warning should be emitted regardless of whether related tests exist.

2. If such behavior only occurs in check but not in test, this is a bug. They should occur both in check and test.

[bobzhang]

there are several issues involved:

1. here whitebox test is generated despite of no whitebox test
2. the whitebox test dropped fn main which used @toml
3. the build system prints out the command first (concurrency involved) and warnings later,
   this can be work around using moon test -j1 xx

The solution maybe not dropping the main function, but rename it to another one.
Note this also explains the inconsistency between moon check and moon test, the former is optimized for speed.