checkregression.py

#!/usr/bin/env python
# -*- coding: utf-8 -*-

## This script has two purposes: detect any tool that *regressed*, which is used
## during the week before the beta branches to reject PRs; and detect any tool
## that *changed* to see if we need to update the toolstate repo.

import sys
import json

# Regressions for these tools during the beta cutoff week do not cause failure.
# See `status_check` in `checktools.sh` for tools that have to pass on the
# beta/stable branches.
REGRESSION_OK = ["rustc-guide", "miri", "embedded-book"]

if __name__ == '__main__':
    os_name = sys.argv[1]
    toolstate_file = sys.argv[2]
    current_state = sys.argv[3]
    verb = sys.argv[4] # 'regressed' or 'changed'

    with open(toolstate_file, 'r') as f:
        toolstate = json.load(f)
    with open(current_state, 'r') as f:
        current = json.load(f)

    regressed = False
    for cur in current:
        tool = cur['tool']
        state = cur[os_name]
        new_state = toolstate.get(tool, '')
        if verb == 'regressed':
            updated = new_state < state
        elif verb == 'changed':
            updated = new_state != state
        else:
            print('Unknown verb {}'.format(updated))
            sys.exit(2)
        if updated:
            print(
                'The state of "{}" has {} from "{}" to "{}"'
                .format(tool, verb, state, new_state)
            )
            if not (verb == 'regressed' and tool in REGRESSION_OK):
                regressed = True

    if regressed:
        sys.exit(1)