Rename a few things and add error handling to get_environment_specifier_handler

conda/env/specs/__init__.py

@@ -10,7 +10,7 @@
 from ...exceptions import (
     EnvironmentFileExtensionNotValid,
     EnvironmentFileNotFound,
-    EnvSpecPluginNotDetected,
+    EnvironmentSpecPluginNotDetected,
     SpecNotFound,
 )
 from ...gateways.connection.session import CONDA_SESSION_SCHEMES
@@ -26,7 +26,7 @@
 @deprecated(
     "25.9",
     "26.3",
-    addendum="Use conda.base.context.plugin_manager.get_environment_specifer_handler.",
+    addendum="Use conda.base.context.plugin_manager.get_environment_specifiers.",
 )
 def get_spec_class_from_file(filename: str) -> FileSpecTypes:
     """
@@ -50,7 +50,9 @@ def get_spec_class_from_file(filename: str) -> FileSpecTypes:
     )
     if file_exists:
         if ext == "" or ext not in all_valid_exts:
-            raise EnvironmentFileExtensionNotValid(filename)
+            raise EnvironmentFileExtensionNotValid(
+                filename, extensions=list(all_valid_exts)
+            )
         elif ext in YamlFileSpec.extensions:
             return YamlFileSpec
         elif ext in RequirementsSpec.extensions:
@@ -62,19 +64,19 @@ def get_spec_class_from_file(filename: str) -> FileSpecTypes:
 @deprecated.argument(
     "25.9", "26.3", "directory", addendum="Specify the full path in filename"
 )
-def detect(
-    filename: str | None = None,
-) -> SpecTypes:
+def detect(filename: str | None = None) -> SpecTypes:
     """
     Return the appropriate spec type to use.
 
     :raises SpecNotFound: Raised if no suitable spec class could be found given the input
     """
+    if filename is None:
+        raise SpecNotFound("No filename provided")
+
     try:
-        spec_hook = context.plugin_manager.get_environment_specifier_handler(
+        spec_hook = context.plugin_manager.get_environment_specifiers(
             filename=filename,
         )
-    except EnvSpecPluginNotDetected as e:
+        return spec_hook.environment_spec(filename)
+    except EnvironmentSpecPluginNotDetected as e:
         raise SpecNotFound(e.message)
-
-    return spec_hook.environment_spec(filename)

conda/exceptions.py

@@ -1251,8 +1251,13 @@ def __init__(self, filename: os.PathLike, *args, **kwargs):
 
 
 class EnvironmentFileExtensionNotValid(CondaEnvException):
-    def __init__(self, filename: os.PathLike, *args, **kwargs):
-        msg = f"'{filename}' file extension must be one of '.txt', '.yaml' or '.yml'"
+    def __init__(
+        self, filename: os.PathLike, extensions: list | None = None, *args, **kwargs
+    ):
+        if extensions is None:
+            extensions = [".txt", ".yaml", ".yml"]
+        extensions_str = ", ".join(extensions)
+        msg = f"'{filename}' file extension must be one of: {extensions_str}"
         self.filename = filename
         super().__init__(msg, *args, **kwargs)
 
@@ -1272,16 +1277,7 @@ def __init__(self, username: str, packagename: str, *args, **kwargs):
         super().__init__(msg, *args, **kwargs)
 
 
-class SpecNotFound(CondaError):
-    def __init__(self, msg: str, *args, **kwargs):
-        super().__init__(msg, *args, **kwargs)
-
-
-class PluginError(CondaError):
-    pass
-
-
-class EnvSpecPluginNotDetected(CondaError):
+class EnvironmentSpecPluginNotDetected(CondaError):
     def __init__(self, name, plugin_names, *args, **kwargs):
         self.name = name
         msg = dals(
@@ -1295,6 +1291,15 @@ def __init__(self, name, plugin_names, *args, **kwargs):
         super().__init__(msg, *args, **kwargs)
 
 
+class SpecNotFound(CondaError):
+    def __init__(self, msg: str, *args, **kwargs):
+        super().__init__(msg, *args, **kwargs)
+
+
+class PluginError(CondaError):
+    pass
+
+
 def maybe_raise(error: BaseException, context: Context):
     if isinstance(error, CondaMultiError):
         groups = groupby(lambda e: isinstance(e, ClobberError), error.errors)

conda/plugins/manager.py

@@ -12,6 +12,7 @@
 
 import functools
 import logging
+import os
 from importlib.metadata import distributions
 from inspect import getmodule, isclass
 from typing import TYPE_CHECKING, overload
@@ -24,7 +25,8 @@
 from ..deprecations import deprecated
 from ..exceptions import (
     CondaValueError,
-    EnvSpecPluginNotDetected,
+    EnvironmentSpecPluginNotDetected,
+    EnvironmentFileExtensionNotValid,
     PluginError,
 )
 from . import (
@@ -487,17 +489,42 @@ def load_settings(self) -> None:
         for name, (parameter, aliases) in self.get_settings().items():
             add_plugin_setting(name, parameter, aliases)
 
-    def get_environment_specifier_handler(
-        self, filename: str
-    ) -> CondaEnvironmentSpecifier:
+    def get_environment_specifiers(self, filename: str) -> CondaEnvironmentSpecifier:
         hooks = self.get_hook_results("environment_specifiers")
-        for hook in hooks:
-            if hook.environment_spec(filename).can_handle():
-                return hook
+        if filename.startswith("file://"):
+            filename = filename[len("file://") :]
 
-        # raise error if no plugins found that can read the environment file
-        hook_names = [h.name for h in hooks]
-        raise EnvSpecPluginNotDetected(name=filename, plugin_names=hook_names)
+        # Check extensions
+        hook_extensions = set().union(
+            *(hook.environment_spec.extensions for hook in hooks)
+        )
+        _, ext = os.path.splitext(filename)
+        if ext == "" or ext not in hook_extensions:
+            raise EnvironmentFileExtensionNotValid(filename, extensions=hook_extensions)
+
+        # Find a spec that can handle the filename
+        capable_hooks = [
+            hook for hook in hooks if hook.environment_spec(filename).can_handle()
+        ]
+        if len(capable_hooks) == 1:
+            return capable_hooks[0]
+        elif len(capable_hooks) > 1:
+            raise PluginError(
+                dals(
+                    f"""
+                    Multiple plugins found that can handle the environment file '{filename}':
+
+                    {", ".join([hook.name for hook in capable_hooks])}
+
+                    Please make sure that you don't have any incompatible plugins installed.
+                    """
+                )
+            )
+        else:
+            # raise error if no plugins found that can read the environment file
+            raise EnvironmentSpecPluginNotDetected(
+                name=filename, plugin_names=[hook.name for hook in hooks]
+            )
 
 
 @functools.cache

tests/plugins/test_env_specs.py

@@ -4,7 +4,7 @@
 
 from conda import plugins
 from conda.env.env import Environment
-from conda.exceptions import EnvSpecPluginNotDetected
+from conda.exceptions import EnvironmentSpecPluginNotDetected
 from conda.plugins.types import CondaEnvironmentSpecifier, EnvironmentSpecBase
 
 
@@ -57,5 +57,5 @@ def test_raises_an_error_if_file_is_unhandleable(dummy_random_spec_plugin):
     """
     Ensures that our dummy random spec does not recognize non-".random" files
     """
-    with pytest.raises(EnvSpecPluginNotDetected):
+    with pytest.raises(EnvironmentSpecPluginNotDetected):
         dummy_random_spec_plugin.get_environment_specifier_handler("test.random-not")