Very rough implementation

src/tox_current_env/hooks.py

@@ -1,6 +1,66 @@
+import os
+import shutil
+import sys
 import tox
 
 
+@tox.hookimpl
+def tox_addoption(parser):
+    parser.add_argument(
+        "--current-env",
+        action="store_true",
+        dest="current_env",
+        default=False,
+        help="Run tests in current environment, not creating any virtual environment",
+    )
+    parser.add_argument(
+        "--print-deps-only",
+        action="store_true",
+        dest="print_deps_only",
+        default=False,
+        help="Don't run tests, only print the dependencies",
+    )
+
+
+@tox.hookimpl
+def tox_configure(config):
+    """Stores a global varibale with current_env option.
+    Makes all commands external"""
+    if config.option.print_deps_only:
+        config.skipsdist = True
+    elif config.option.current_env:
+        config.option.recreate = True
+        config.skipsdist = True
+        for testenv in config.envconfigs:
+            config.envconfigs[testenv].whitelist_externals = "*"
+
+    return config
+
+
 @tox.hookimpl
 def tox_testenv_create(venv, action):
-    ...
+    """We don't create anything"""
+    config = venv.envconfig.config
+    if config.option.current_env or config.option.print_deps_only:
+        link = venv.envconfig.get_envpython()
+        target = sys.executable
+        shutil.rmtree(os.path.dirname(link), ignore_errors=True)
+        os.makedirs(os.path.dirname(link))
+        os.symlink(target, link)
+        return True
+
+
+@tox.hookimpl
+def tox_testenv_install_deps(venv, action):
+    """We don't install anything"""
+    config = venv.envconfig.config
+    if config.option.current_env or config.option.print_deps_only:
+        return True
+
+
+@tox.hookimpl
+def tox_runtest(venv, redirect):
+    if venv.envconfig.config.option.print_deps_only:
+        for depndency in venv.get_resolved_dependencies():
+            print(depndency)
+        return True