Migrate treegen module and adapt it

[ochaplashkin]

Introduce preloaded hooks

Preloaded hooks extend base hooks. They behave like the pytest fixture with the autouse parameter. This is useful when writing a module and using it with "auto" before/after hooks.

The following functions have been "preloaded" into hooks.lua module:

• before_suite_preloaded(func)
• after_suite_preloaded(func)
• before_all_preloaded(func)
• after_all_preloaded(func)
• before_each_preloaded(func)
• after_each_preloaded(func)

Closes #380

Migrate treegen module and adapt it

The original treegen module (path: tarantool/test/treegen.lua) has been moved to the current project with the following changes:

• refactoring;
• updated documentation.

Closes #364

[ochaplashkin]

Hmm

1) treegen.test_init_without_explicit_hooks
/home/runner/work/luatest/luatest/test/treegen_test.lua:10: expected: {}
actual: nil

It's very strange, because everything is ok on my host:

$ ./bin/luatest -c -v ./test/treegen_test.lua 
Tarantool version is 2.11.0-0-g247a9a418
Started on Thu Jun  6 00:18:01 2024
    treegen.test_init_without_explicit_hooks ... 
    treegen.test_init_without_explicit_hooks ... (0.000s) Ok
    treegen.test_add_template ... 
    treegen.test_add_template ... (0.000s) Ok
    treegen.test_prepare_directory ... 
    treegen.test_prepare_directory ... (0.001s) Ok
    treegen.test_clean_keep_data ... 
    treegen.test_clean_keep_data ... (0.001s) Ok
=========================================================
Ran 4 tests in 0.003 seconds, 4 succeeded, 0 failed

[Totktonada]

@ochaplashkin I see two facts that may be useful for debugging.

1. The test cases order is randomized in CI. It is likely the root of the difference with your local run.

2. There is another error in CI before the quoted one:

   <...>/luatest/treegen.lua:132: bad argument #1 to 'insert' (table expected, got nil)

[ochaplashkin]

Ldoc render (screenshots)

treegen module:

and

[Totktonada]

No objections from my side.