Roadmap: Version 1.0

[b0g3r]

• [ ] perseus works exactly as snapshottest, but with interactive mode while updating
• [x] perseus is autotested
• [ ] perseus mentions shapshottest in README
• [ ] perseus has cool GIF in README
• [ ] perseus used in one OS project or more
• [ ] repo has working CI/CD
• [ ] perseus has CLI for replacing current snapshottest

[Bobronium]

For test writing we could use semething similar to pydantic.tests.conftest.create_module paired with pytest invoking, like so:

def test_perseus_ok(create_test):
    @create_test  # will create test_module.py and return some special object
    def test_module():
        def test_foo(snapshot):
            assert snapshot.match('foo')
     result = pytest.main([test_module.path])  # or test_module.run()
     ...

I'll try to dig into this on the next weekend.

[b0g3r]

Also check https://github.com/syrusakbary/snapshottest/blob/master/tests/test_pytest.py

[b0g3r]

How to test pytest plugins https://docs.pytest.org/en/stable/writing_plugins.html#testing-plugins

[b0g3r]

PoC with pytester looks like:

from _pytest.pytester import Testdir

def test_1(testdir: Testdir):
    testdir.makepyfile(
        '''
        def test_1(snapshot):
            snapshot.assert_match('test sstring')
        '''
    )
    snapshot_file = testdir.mkpydir('snapshots').ensure('snap_test_1.py')
    snapshot_file.write_text(
        '''
# -*- coding: utf-8 -*-
# snapshottest: v1 - https://goo.gl/zC4yUc
from __future__ import unicode_literals

from perseus._vendor.snapshottest import Snapshot

snapshots = Snapshot()

snapshots['test_1 1'] = 'test string'
        ''',
        encoding='utf-8'
    )
    result = testdir.runpytest()
    assert result

The next steps:

• try to use stdin: https://github.com/pytest-dev/pytest/pull/5059
• try to use "copy_example"

[b0g3r]

Yep, it's working. Unfortunately runpytest() doesn't pass stdin kwargs to popen, so I manually copied the method and add stdin 🤦 :

    p = make_numbered_dir(root=Path(str(testdir.tmpdir)), prefix="runpytest-")
    args = ("--basetemp=%s" % p,)
    plugins = [x for x in testdir.plugins if isinstance(x, str)]
    if plugins:
        args = ("-p", plugins[0]) + args
    args = testdir._getpytestargs() + args
    result = testdir.run(*args, stdin=b'y')

It's working 🎉

I'll try to write a convenient wrapper around it with (test, snapshot) -> (pytest_runner, snapshot_file), maybe with copy_example

[b0g3r]

Sorry, I pushed it into the master branch, but I did it. Can you check it? 8de5070e75f887691ff61b688e15c19033258a8d

[Bobronium]

Running subprocess for each test might be really slow. Maybe there is a way to stick to "inprocess" method?

I almost got it to work (with testdir), but had troubles with input suppressing. I'd preferred faster method, if that's doable.

What do you think?

Upd. BTW, maybe we should create separate issue for this discussion?