Add very basic integration tests

.gitignore

@@ -1,3 +1,8 @@
 __pycache__/
-/build/
-/dist/
+build/
+dist/
+.tox/
+*.tar.gz
+*.zip
+*.egg-info
+*.dist-info

tests/setup.py

@@ -0,0 +1,3 @@
+from setuptools import setup
+
+setup(name="test")

tests/test_integration.py

@@ -0,0 +1,77 @@
+import os
+import pathlib
+import shutil
+import subprocess
+import sys
+
+import pytest
+
+
+NATIVE_TOXENV = f"py{sys.version_info[0]}{sys.version_info[1]}"
+NATIVE_EXECUTABLE = str(pathlib.Path(sys.executable).resolve())
+TOX_INI = pathlib.Path(__file__).parent / "tox.ini"
+DOT_TOX = pathlib.Path(__file__).parent / ".tox"
+
+
+def tox(*args, prune=True, **kwargs):
+    if prune:
+        shutil.rmtree(DOT_TOX, ignore_errors=True)
+    kwargs.setdefault("encoding", "utf-8")
+    kwargs.setdefault("stdout", subprocess.PIPE)
+    kwargs.setdefault("stderr", subprocess.PIPE)
+    kwargs.setdefault("check", True)
+    cp = subprocess.run((sys.executable, "-m", "tox", "-qc", TOX_INI) + args, **kwargs)
+    print(cp.stdout, file=sys.stdout)
+    print(cp.stderr, file=sys.stderr)
+    return cp
+
+
+def test_native_toxenv_current_env():
+    result = tox("-e", NATIVE_TOXENV, "--current-env")
+    assert result.stdout.splitlines()[0] == NATIVE_EXECUTABLE
+
+
+def test_all_toxenv_current_env():
+    result = tox("--current-env", check=False)
+    assert NATIVE_EXECUTABLE in result.stdout.splitlines()
+    assert result.stdout.count("InterpreterMismatch:") >= 2
+    assert result.returncode > 0
+
+
+def test_all_toxenv_current_env_skip_missing():
+    result = tox("--current-env", "--skip-missing-interpreters", check=False)
+    assert "InterpreterMismatch:" in result.stdout
+    assert "congratulations" in result.stdout
+    assert result.returncode == 0
+
+
+def test_native_toxenv_print_deps_only():
+    result = tox("-e", NATIVE_TOXENV, "--print-deps-only")
+    assert result.stdout.splitlines()[0] == "six"
+    assert result.stdout.splitlines()[1] == "py"
+
+
+def test_regular_run():
+    result = tox()
+    lines = sorted(result.stdout.splitlines()[:3])
+    assert "/.tox/py36/bin/python" in lines[0]
+    assert "/.tox/py37/bin/python" in lines[1]
+    assert "/.tox/py38/bin/python" in lines[2]
+    assert "congratulations" in result.stdout
+
+
+def test_regular_after_current():
+    tox("-e", NATIVE_TOXENV, "--current-env")
+    result = tox("-e", NATIVE_TOXENV, prune=False)
+    assert f"/.tox/{NATIVE_TOXENV}/bin/python" in result.stdout.splitlines()[0]
+
+
+@pytest.mark.xfail(reason="Regular tox refuses to remove our fake virtualenv")
+def test_regular_recreate_after_current():
+    tox("-e", NATIVE_TOXENV, "--current-env")
+    tox("-re", NATIVE_TOXENV, prune=False)
+
+
+def test_current_after_regular():
+    tox("-e", NATIVE_TOXENV)
+    tox("-e", NATIVE_TOXENV, "--current-env", prune=False)

tests/tox.ini

@@ -0,0 +1,9 @@
+[tox]
+envlist = py36,py37,py38
+
+[testenv]
+deps =
+    six
+    py
+commands =
+    python -c 'import os, sys; print(os.path.realpath(sys.executable))'

tox.ini

@@ -0,0 +1,7 @@
+[tox]
+envlist = py36,py37,py38
+
+[testenv]
+deps = pytest
+commands =
+    pytest tests -v