Create current environemnt link when --print-deps-only has no env

Fixes https://github.com/fedora-python/tox-current-env/issues/9

src/tox_current_env/hooks.py

@@ -54,6 +54,11 @@ def is_proper_venv(venv):
     return python and activate
 
 
+def is_any_env(venv):
+    python, activate = _python_activate_exists(venv)
+    return python
+
+
 def unsupported_raise(config, venv):
     if config.option.recreate:
         return
@@ -72,10 +77,19 @@ def unsupported_raise(config, venv):
 def tox_testenv_create(venv, action):
     """We create a fake virtualenv with just the symbolic link"""
     config = venv.envconfig.config
+    create_fake_env = check_version = config.option.current_env
     if config.option.print_deps_only:
-        # We don't need anything
-        return True
-    if config.option.current_env:
+        if is_any_env(venv):
+            # We don't need anything
+            return True
+        else:
+            # We need at least some kind of environment,
+            # or tox fails without a python command
+            # We fallback to --current-env behavior,
+            # because it's cheaper, faster and won't install stuff
+            create_fake_env = True
+    if check_version:
+        # With real --current-env, we check this, but not with --print-deps-only only
         version_info = venv.envconfig.python_info.version_info
         if version_info is None:
             raise tox.exception.InterpreterNotFound(venv.envconfig.basepython)
@@ -85,7 +99,7 @@ def tox_testenv_create(venv, action):
                 + f"    in current env: {tuple(sys.version_info)}\n"
                 + f"    requested: {version_info}"
             )
-
+    if create_fake_env:
         # Make sure the `python` command on path is sys.executable.
         # (We might have e.g. /usr/bin/python3, not `python`.)
         # Remove the rest of the virtualenv.

tests/test_integration.py

@@ -195,3 +195,24 @@ def test_regular_after_deps_only():
     result = tox("-e", NATIVE_TOXENV, "--print-deps-only", prune=False)
     assert "bin/python" not in result.stdout
     assert "six" in result.stdout
+
+
+def test_print_deps_without_python_command(tmp_path):
+    bin = tmp_path / "bin"
+    bin.mkdir()
+    tox_link = bin / "tox"
+    tox_path = shutil.which("tox")
+    tox_link.symlink_to(tox_path)
+    env = {**os.environ, "PATH": str(bin)}
+
+    result = tox("-e", NATIVE_TOXENV, "--print-deps-only", env=env)
+    expected = textwrap.dedent(
+        f"""
+        six
+        py
+        ___________________________________ summary ____________________________________
+          {NATIVE_TOXENV}: commands succeeded
+          congratulations :)
+        """
+    ).lstrip()
+    assert result.stdout == expected