Define exceptions with @attr.s(hash=True)

otherwise they don't work with the Python traceback machinery.

Author: radix

.gitignore

@@ -4,3 +4,4 @@ build/
 effect.egg-info/
 dist/
 *~
+.pytest_cache

Pipfile

@@ -0,0 +1,23 @@
+[[source]]
+
+url = "https://pypi.python.org/simple"
+verify_ssl = true
+name = "pypi"
+
+
+[requires]
+
+python_version = "3.5"
+
+
+[packages]
+
+six = "~=1.11.0"
+attrs = "~=17.4.0"
+
+
+[dev-packages]
+
+pytest = "~=3.4.1"
+testtools = "~=2.3.0"
+"flake8" = "~=3.5.0"

Pipfile.lock

@@ -87,7 +87,7 @@ def parallel_all_errors(effects):
     return Effect(ParallelEffects(list(effects)))
 
 
-@attr.s
+@attr.s(hash=True)
 class FirstError(Exception):
     """
     One of the effects in a :obj:`ParallelEffects` resulted in an error. This

effect/_intents.py

@@ -12,7 +12,7 @@
 from ._test_utils import MatchesReraisedExcInfo, get_exc_info
 
 
-@attr.s
+@attr.s(hash=True)
 class EquitableException(Exception):
     message = attr.ib()