Allow --rm to remove a virtualenv by its dependencies

README.rst

@@ -438,6 +438,12 @@ virtual environment matching the provided UUID if such environment exists (one e
 way to find out the environment's UUID is calling *fades* with the
 ``--where`` option).
 
+Alternatively, you can pass ``--rm`` without a UUID and indicate the dependencies
+instead; *fades* will then remove the virtual environment that matches those
+dependencies, just like it would select it to run something::
+
+    fades --rm -d django
+
 Another way to clean up the cache is to remove all venvs that haven't been used for some time.
 In order to do this you need to call *fades* with ``--clean-unused-venvs``.
 When fades it's called with this option, it runs in mantain mode, this means that fades will exit
@@ -487,6 +493,10 @@ Remove a virtual environment matching the given uuid from disk and cache index::
 
     fades --rm 89a2bf83-c280-4918-a78d-c35506efd69d
 
+Remove the virtual environment matching the indicated dependencies from disk and cache index::
+
+    fades --rm -d django
+
 Download the script from the given pastebin and executes it (previously building a virtual environment for the dependencies indicated in that pastebin, of course)::
 
     fades http://linkode.org/#4QI4TrPlGf1gK2V7jPBC47

fades/main.py

@@ -45,6 +45,10 @@
 # the rest of the module just fine
 logger = logging.getLogger('fades')
 
+# sentinel used as the '--rm' value when it's given as a bare flag (no UUID), meaning
+# "remove the virtualenv that matches the indicated dependencies"
+REMOVE_BY_DEPS = object()
+
 # the signals to redirect to the child process (note: only these are
 # allowed in Windows, see 'signal' doc).
 REDIRECTED_SIGNALS = [
@@ -260,8 +264,10 @@ def go():
         '--python-options', action='append', default=[],
         help="extra options to be supplied to python (this option can be used multiple times)")
     parser.add_argument(
-        '--rm', dest='remove', metavar='UUID',
-        help="remove a virtualenv by UUID; see --where option to easily find out the UUID")
+        '--rm', dest='remove', metavar='UUID', nargs='?', const=REMOVE_BY_DEPS, default=None,
+        help="remove a virtualenv: by UUID if one is given (see --where to easily find out the "
+             "UUID), or by the indicated dependencies if no UUID is passed "
+             "(e.g. 'fades --rm -d django')")
     parser.add_argument(
         '--clean-unused-venvs', action='store',
         help="remove venvs that haven't been used for more than the indicated days and compact "
@@ -360,22 +366,6 @@ def go():
         usage_manager.clean_unused_venvs(max_days_to_keep)
         return 0
 
-    uuid = args.remove
-    if uuid:
-        venv_data = venvscache.get_venv(uuid=uuid)
-        if venv_data:
-            # remove this venv from the cache
-            env_path = venv_data.get('env_path')
-            if env_path:
-                envbuilder.destroy_venv(env_path, venvscache)
-            else:
-                logger.warning(
-                    "Invalid 'env_path' found in virtualenv metadata: %r. "
-                    "Not removing virtualenv.", env_path)
-        else:
-            logger.warning('No virtualenv found with uuid: %s.', uuid)
-        return 0
-
     # decided which the child program really is
     analyzable_child_program, child_program = decide_child_program(
         args.executable, args.module, args.child_program)
@@ -384,10 +374,6 @@ def go():
     indicated_deps = consolidate_dependencies(
         args.ipython, analyzable_child_program, args.requirement, args.dependency)
 
-    # Check for packages updates
-    if args.check_updates:
-        helpers.check_pypi_updates(indicated_deps)
-
     # get the interpreter version requested for the child_program
     interpreter, is_current = helpers.get_interpreter_version(args.python)
 
@@ -399,8 +385,33 @@ def go():
     if args.system_site_packages:
         options['venv_options'].append("--system-site-packages")
 
+    # remove a virtualenv, either by the given UUID or by the indicated dependencies
+    if args.remove is not None:
+        if args.remove is REMOVE_BY_DEPS:
+            venv_data = venvscache.get_venv(indicated_deps, interpreter, options=options)
+            descriptor = "the indicated dependencies"
+        else:
+            venv_data = venvscache.get_venv(uuid=args.remove)
+            descriptor = "uuid: {}".format(args.remove)
+        if venv_data:
+            # remove this venv from the cache
+            env_path = venv_data.get('env_path')
+            if env_path:
+                envbuilder.destroy_venv(env_path, venvscache)
+            else:
+                logger.warning(
+                    "Invalid 'env_path' found in virtualenv metadata: %r. "
+                    "Not removing virtualenv.", env_path)
+        else:
+            logger.warning('No virtualenv found with %s.', descriptor)
+        return 0
+
+    # Check for packages updates
+    if args.check_updates:
+        helpers.check_pypi_updates(indicated_deps)
+
     create_venv = False
-    venv_data = venvscache.get_venv(indicated_deps, interpreter, uuid, options)
+    venv_data = venvscache.get_venv(indicated_deps, interpreter, options=options)
     if venv_data:
         env_path = venv_data['env_path']
         # A venv was found in the cache check if its valid or re-generate it.

man/fades.1

@@ -14,7 +14,7 @@ fades - A system that automatically handles the virtualenvs in the cases normall
 [\fB-r\fR][\fB--requirement\fR]
 [\fB-x\fR][\fB--exec\fR]
 [\fB-p\fR \fIversion\fR][\fB--python\fR=\fIversion\fR]
-[\fB--rm\fR=\fIUUID\fR]
+[\fB--rm\fR[=\fIUUID\fR]]
 [\fB--system-site-packages\fR]
 [\fB--venv-options\fR=\fIoptions\fR]
 [\fB--pip-options\fR=\fIoptions\fR]
@@ -91,8 +91,8 @@ The dependencies can be indicated in multiple places (in the Python source file,
 Execute the \fIchild_program\fR in the context of the virtual environment. The child_program, which in this case becomes a mandatory parameter, can be just the executable name (relative to the venv's bin directory) or an absolute path.
 
 .TP
-.BR --rm " " \fIUUID\fR
-Remove a virtual environment by UUID.  See \fB--get-venv-dir\fR option to easily find out the UUID.
+.BR --rm " " [\fIUUID\fR]
+Remove a virtual environment.  If a UUID is given, the environment with that UUID is removed (see \fB--get-venv-dir\fR option to easily find out the UUID); if no UUID is given, the environment matching the indicated dependencies is removed (e.g. \fBfades --rm -d django\fR).
 
 .TP
 .BR --system-site-packages ""

tests/test_main.py

@@ -19,7 +19,7 @@
 import os
 import unittest
 from pathlib import Path
-from unittest.mock import patch
+from unittest.mock import MagicMock, patch
 
 from packaging.requirements import Requirement
 
@@ -233,6 +233,57 @@ def test_module(self):
         self.assertEqual(child, child_path)
 
 
+class RemoveVenvTestCase(unittest.TestCase):
+    """Check the '--rm' option, removing by uuid or by the indicated dependencies."""
+
+    def _run(self, cmdline_args, found_venv):
+        """Run go() with the given cli args, mocking the cache and the venv destruction.
+
+        'found_venv' is the metadata returned by the cache lookup (or None when nothing matches).
+        Returns the mocked cache and destroy_venv so the test can check how they were called.
+        """
+        venvscache = MagicMock()
+        venvscache.get_venv.return_value = found_venv
+        with patch('sys.argv', ['fades'] + cmdline_args), \
+                patch('fades.main.detect_inside_virtualenv', return_value=False), \
+                patch('fades.cache.VEnvsCache', return_value=venvscache), \
+                patch('fades.envbuilder.UsageManager'), \
+                patch('fades.helpers.get_basedir', return_value=Path('/tmp/fades-test')), \
+                patch('fades.envbuilder.destroy_venv') as destroy_venv:
+            result = main.go()
+        self.assertEqual(result, 0)
+        return venvscache, destroy_venv
+
+    def test_by_uuid_found(self):
+        venvscache, destroy_venv = self._run(
+            ['--rm', 'some-uuid'], found_venv={'env_path': '/path/to/venv'})
+        venvscache.get_venv.assert_called_once_with(uuid='some-uuid')
+        destroy_venv.assert_called_once_with('/path/to/venv', venvscache)
+
+    def test_by_uuid_not_found(self):
+        venvscache, destroy_venv = self._run(['--rm', 'some-uuid'], found_venv=None)
+        venvscache.get_venv.assert_called_once_with(uuid='some-uuid')
+        destroy_venv.assert_not_called()
+
+    def test_by_uuid_invalid_env_path(self):
+        _, destroy_venv = self._run(['--rm', 'some-uuid'], found_venv={'env_path': None})
+        destroy_venv.assert_not_called()
+
+    def test_by_dependencies_found(self):
+        venvscache, destroy_venv = self._run(
+            ['--rm', '-d', 'foo'], found_venv={'env_path': '/path/to/venv'})
+        # the lookup is done by the indicated dependencies, not by uuid
+        (_, kwargs) = venvscache.get_venv.call_args
+        self.assertNotIn('uuid', kwargs)
+        deps = venvscache.get_venv.call_args[0][0]
+        self.assertIn('foo', [req.name for req in deps[REPO_PYPI]])
+        destroy_venv.assert_called_once_with('/path/to/venv', venvscache)
+
+    def test_by_dependencies_not_found(self):
+        venvscache, destroy_venv = self._run(['--rm', '-d', 'foo'], found_venv=None)
+        destroy_venv.assert_not_called()
+
+
 # ---------------------------------------
 # autoimport tests