Pytest supports running tests in parallel using the `xdist` plugin. In
order to support it in Picodata, one should avoid ports collision. It
assigns each worker a dedicated IP address `127.7.n.1`, where
`n = xdist_worker_number`. Unfortunately, it doesn't work on MacOS,
because Mac doesn't provide any loopback aliases except `127.0.0.1`
by default.

This patch provides another address generation logics. The `subnet`
parameter is superseeded with a `base_port`, that is `3300 + n * 100`.
In this way, every pytest (xdist) worker gets a dedicated port range
`[3301, 3399]`, `[3401, 3499]` and so on.

Close https://git.picodata.io/picodata/picodata/picodata/-/issues/65

Before this patch, pytest used to launch all instances in a clean
environment. It prevented running with `PICODATA_LOG_LEVEL=verbose`.

Yaroslav Dynnikov authored 2 years ago and Yaroslav Dynnikov committed 2 years ago

This patch covers one more case when discovery request is handled
by an instance that has the discovery module unitialized.

Commit 1a3b5233 missed a bug. Iteration over instances could be aborted
by an exception during teardown. It resulted in garbage process
remaining alive after pytest termination.

Waiting for a valid `leader_id` on a node isn't enough. It may already
have one, but still be a Learner. Instead, the fixture should wait until
the node is promoted to voter.

The assertion `status == "Leader"` was in the first place, and
`raft_timeout_now` call was unreachable.

1. Print logs to the stderr so that they interleave with tarantool logs.
2. Fix `cluster.__repr__()`.

In `conftest.py`:

  - *Add* function `xdist_worker_number`. It converts `str(worker_id)` into `int`.
    It serves as a substitute for `session_data_mutex` for parallel test runs.

  - *Change* `normalize_net_box_result`. Replace a function with a decorator. Also,
    handle typical kinds of picodata responses. Extensively test it in
    `test_basics.py::test_eval/call_normalization`.

  - *Add* dataclass `RaftStatus`. It shouldn't be used outside `conftest.py`. It only makes
    assertions more brief in logs and understndable in code.

  - *Add* all raft stuff into the `Instance` class. This implies `raft_propose_eval`,
    `assert_raft_status` all `promote_or_fail` moved from `util.py`.

  - *Change* fixture `compile`. No need in extra logics since commit 59c31cb8.

  - *Preserve* fixture `binary_path`.

  - *Remove* fixtures `session_data_mutex` and `run_id`. Superseded with `xdist_worker_number`.

  - *Remove* fixtures `run_cluster` and `run_instance`. Superseded with `cluster.deploy(...)`.

  - *Remove* function `wait_tcp_port`. It's never enough to check raw socket. Superseded with
    `instance.wait_ready()`.

  - Give the instances clean names `i1, i2, ...`, and simple addresses `127.7.0.1:3301`.
    For the parallel test run use different IPs `127.7.N.1` etc.

In `test_basics.py`:

  - *Add* `test_xdist_worker_number`.

  - *Add* `test_call_normalization` and `test_eval_normalization`.

  - *Add* `test_process_management`. It's brand new, never implemented in luatest before.

  - *Rename* `test_single_instance_raft_eval` to `test_propose_eval` and extend it with additional
    assertion from `single_test.lua`.

  - *Remove* `test_instance`. A part of its logics is moved to `test_call/eval_normalization`. The
    other part is rewritten and extended in `test_process_management`.

  - *Remove* `test_cluster`. It was completely useless because of inappropriate synchronization and
    no valuable assertions.

  - *Remove* `test_propose_eval`. It wasn't that useful, but failed because of inappropriate
    synchronization.

In `test_couple.py`:

  - *Preserve* `test_follower_proposal` and `test_failover`. Just slightly refactor according to the
    new `conftest.py` API.

In `util.py` (completely removed):

  - *Remove* decorator `retry`. Needless.

  - *Remove* decorator `retry_on_network_errors`. Inappropriate predicate didn't catch Lua errors.

  - *Remove* everything related to raft. Move it into `conftest.py`.

Part of https://git.picodata.io/picodata/picodata/picodata/-/issues/59