python

The atago project wrote these specs on its own initiative and runs them in its own CI, to exercise atago against a real program. They are not python’s official test suite, and the python project is not affiliated with atago.

Summary #

2 suites · 8 scenarios

Contents #

python3 + changes (bytecode cache footprint) #

Running a Python script quietly writes files you did not ask for: importing a local module leaves a compiled .pyc behind in __pycache__, while the entry script itself is never cached. That asymmetry surprises people, so it is pinned here exactly.

The paired scenario pins the escape hatch: with PYTHONDONTWRITEBYTECODE set, the same run creates nothing at all — an empty delta, which is the strongest form this assertion can take.

Source: test/e2e/thirdparty/python/changes.atago.yaml

Scenario: importing a local module writes exactly one .pyc #

only when python3 --version succeeds

Given #

  • Fixture file mymod.py is created.
  • Fixture file main.py is created.

Inputs #

Fixture mymod.py:

def val():
    return 42

Fixture main.py:

import mymod
print(mymod.val())

When #

python3 main.py

Then #

  • exit code is 0
  • stdout equals an exact value
  • the step changed exactly created __pycache__/*.pyc, modified nothing, deleted nothing

Scenario: PYTHONDONTWRITEBYTECODE suppresses the cache entirely #

only when python3 --version succeeds

Given #

  • Fixture file mymod.py is created.
  • Fixture file main.py is created.
  • Environment variables are set: PYTHONDONTWRITEBYTECODE.

Inputs #

Fixture mymod.py:

def val():
    return 42

Fixture main.py:

import mymod
print(mymod.val())

When #

python3 main.py

Then #

  • exit code is 0
  • stdout equals an exact value
  • the step changed exactly created nothing, modified nothing, deleted nothing

python3 REPL (interactive pty testbed) #

The Python REPL is the canonical long-lived interactive session: it prints a prompt, waits, answers, and prompts again, for as many exchanges as you want.

That conversational shape is what this suite pins — recognizing the >>> prompt, carrying on a multi-step exchange where each answer depends on the last, getting a traceback back for bad input without the session dying, and exiting cleanly on end-of-input. Python also behaves differently when it detects a terminal, so that branch is exercised too.

Python is on every CI image, which makes this the most portable worked example here of testing an interactive program — and a template to copy for your own REPL.

Source: test/e2e/thirdparty/python/python.atago.yaml

Scenario: version and -c contracts (non-interactive) #

only when python3 --version succeeds

When #

python3 --version
python3 -c "print('hello from python')"

Then #

  • after python3 --version:
    • exit code is 0
    • stdout matches /^Python 3\./
  • after python3 -c "print('hello from python')":
    • exit code is 0
    • stdout equals an exact value

Scenario: a missing script exits 2 with a can’t-open-file error #

only when python3 --version succeeds

When #

python3 no_such_script.py

Then #

  • exit code is 2
  • stderr contains can't open file

Scenario: stdout is a pipe under run but a tty under pty #

only when python3 --version succeeds · skipped on Windows

When #

python3 -c "import sys; print(sys.stdout.isatty())"
# interactive (pty): python3 -c "import sys; print(sys.stdout.isatty())"

Then #

  • exit code is 0
  • stdout equals an exact value
  • exit code is 0
  • stdout contains True

Scenario: an interactive session drives the REPL across exchanges #

only when python3 --version succeeds · skipped on Windows

When #

# interactive (pty): python3 -q

Then #

  • exit code is 0
  • stdout contains 2, 120

Scenario: EOF (ctrl-d) ends the session cleanly #

only when python3 --version succeeds · skipped on Windows

When #

# interactive (pty): python3 -q

Then #

  • exit code is 0

Scenario: a traceback is reported and the REPL recovers #

only when python3 --version succeeds · skipped on Windows

When #

# interactive (pty): python3 -q

Then #

  • exit code is 0
  • stdout contains ZeroDivisionError, recovered