Add a custom exception class for invalid alias names

hab/errors.py

@@ -22,6 +22,24 @@ class MaxRedirectError(RequirementError):
     """The maximum number of redirects was reached without resolving successfully."""
 
 
+class InvalidAliasError(HabError):
+    """Raised the requested alias was not found.
+
+    Args:
+        alias (str): The requested alias name.
+        cfg (hab.parser.Config): The hab config used to launch the alias.
+        msg (str, optional): The error message. `str.format` is called on this
+            passing the kwargs `alias` and `uri`.
+    """
+
+    def __init__(self, alias, cfg, msg=None):
+        self.alias = alias
+        self.cfg = cfg
+        if msg is None:
+            msg = 'The alias "{alias}" is not found for URI "{uri}".'
+        super().__init__(msg.format(alias=alias, uri=cfg.uri))
+
+
 class InvalidRequirementError(RequirementError):
     """Raised if unable to resolve a given requirement."""
 

hab/parsers/config.py

@@ -2,7 +2,7 @@
 import os
 
 from .. import NotSet, utils
-from ..errors import HabError
+from ..errors import HabError, InvalidAliasError
 from .hab_base import HabBase
 from .meta import hab_property
 
@@ -71,7 +71,7 @@ def launch(self, alias_name, args=None, blocking=False, cls=None, **kwargs):
         """
         # Construct the command line arguments to execute
         if alias_name not in self.aliases:
-            raise HabError(f'"{alias_name}" is not a valid alias name')
+            raise InvalidAliasError(alias_name, self)
         alias = self.aliases[alias_name]
 
         # Get the subprocess.Popen like class to use to launch the alias

hab/parsers/hab_base.py

@@ -9,7 +9,12 @@
 from packaging.version import Version
 
 from .. import NotSet, utils
-from ..errors import DuplicateJsonError, HabError, ReservedVariableNameError
+from ..errors import (
+    DuplicateJsonError,
+    HabError,
+    InvalidAliasError,
+    ReservedVariableNameError,
+)
 from ..formatter import Formatter
 from ..site import MergeDict
 from ..solvers import Solver
@@ -809,7 +814,7 @@ def generate_config_script(
 
             # Get the cmd to launch, raising useful errors if invalid
             if launch not in self.aliases:
-                raise HabError(f'"{launch}" is not a valid alias name')
+                raise InvalidAliasError(launch, self)
             alias = self.aliases.get(launch, {})
 
             try:

tests/test_launch.py

@@ -8,7 +8,7 @@
 import pytest
 
 from hab import Resolver, Site, utils
-from hab.errors import HabError
+from hab.errors import HabError, InvalidAliasError
 
 
 class Topen(subprocess.Popen):
@@ -115,7 +115,10 @@ def test_pythonw(monkeypatch, resolver):
 
 def test_invalid_alias(resolver):
     cfg = resolver.resolve("app/aliased/mod")
-    with pytest.raises(HabError, match='"not-a-alias" is not a valid alias name'):
+    with pytest.raises(
+        InvalidAliasError,
+        match='The alias "not-a-alias" is not found for URI "app/aliased/mod".',
+    ):
         cfg.launch("not-a-alias")
 
     # Remove the "cmd" value to test an invalid configuration

tests/test_scripts.py

@@ -291,7 +291,10 @@ def test_invalid_alias(uncached_resolver, tmpdir, ext):
 
     # Check that calling a bad alias name raises a useful error message
     cfg = uncached_resolver.resolve("not_set/child")
-    with pytest.raises(errors.HabError, match=r'"bad-alias" is not a valid alias name'):
+    with pytest.raises(
+        errors.InvalidAliasError,
+        match=r'The alias "bad-alias" is not found for URI "not_set/child".',
+    ):
         cfg.write_script(str(tmpdir), launch="bad-alias", **kwargs)
 
     # Remove the "cmd" value to test an invalid configuration