Warn when an non-existent prefix path is specified for rename (cond…

…a#13387)

* Disallow protected directory paths from being able to be specified as a new conda environment prefix

* Update check_prefix function, add tests

* Relax dir pattern matching in install.py and update failing test

* Update install.py check_prefix function to check for protected dirs and provide a warning vs prevent the env from being created

* Add helpful error message to main_rename.py for nonexistent prefix

* Revert changes to install.py and main_create.py

* Add news file

conda/cli/main_rename.py

@@ -79,16 +79,20 @@ def configure_parser(sub_parsers: _SubParsersAction, **kwargs) -> ArgumentParser
 @deprecated.argument("24.3", "24.9", "prefix")
 def validate_src() -> str:
     """
-    Validate that we are receiving at least one value for --name or --prefix
-    and ensure that the "base" environment is not being renamed
+    Validate that we are receiving at least one valid value for --name or
+    --prefix and ensure that the "base" environment is not being renamed
     """
     from ..base.context import context
     from ..exceptions import CondaEnvException
 
-    if Path(context.target_prefix).samefile(context.root_prefix):
+    prefix = Path(context.target_prefix)
+    if not prefix.exists():
+        raise CondaEnvException(
+            "The environment you are trying to rename does not exist."
+        )
+    if prefix.samefile(context.root_prefix):
         raise CondaEnvException("The 'base' environment cannot be renamed")
-
-    if Path(context.target_prefix).samefile(context.active_prefix):
+    if prefix.samefile(context.active_prefix):
         raise CondaEnvException("Cannot rename the active environment")
 
     return context.target_prefix

news/13387-warn-when-renaming-nonexistent-prefix

@@ -0,0 +1,19 @@
+### Enhancements
+
+* Provide a more useful warning when attempting to rename a non-existent prefix. (#13387)
+
+### Bug fixes
+
+* <news item>
+
+### Deprecations
+
+* <news item>
+
+### Docs
+
+* <news item>
+
+### Other
+
+* <news item>

tests/cli/test_main_rename.py

@@ -155,6 +155,20 @@ def test_cannot_rename_active_env_by_name(
         locate_prefix_by_name(env_rename)
 
 
+def test_cannot_rename_nonexistent_env(conda_cli: CondaCLIFixture, env_rename: str):
+    """Show a useful error message when trying to rename a non-existing env"""
+    with pytest.raises(
+        CondaEnvException,
+        match="The environment you are trying to rename does not exist",
+    ):
+        env_dir = Path(context.root_prefix) / "foo"
+        conda_cli("rename", "--prefix", env_dir, env_rename)
+
+    assert Path(env_dir).exists() is False
+    with pytest.raises(EnvironmentNameNotFound):
+        locate_prefix_by_name(env_rename)
+
+
 def test_rename_with_force(conda_cli: CondaCLIFixture, env_one: str, env_two: str):
     """
     Runs a test where we specify the --force flag to remove an existing directory.