PersistentHashWalkMapper: doc fixes, add test

pymbolic/mapper/__init__.py

@@ -711,7 +711,7 @@ class WalkMapper(RecursiveMapper):
     visited subexpression.
 
     ``map_...`` methods are required to call :meth:`visit` *before*
-        descending to visit their chidlren.
+        descending to visit their children.
 
     .. method:: visit(expr, *args, **kwargs)
 

pymbolic/mapper/persistent_hash.py

@@ -25,7 +25,7 @@
 
 
 class PersistentHashWalkMapper(WalkMapper):
-    """A subclass of :class:`loopy.symbolic.WalkMapper` for constructing
+    """A subclass of :class:`pymbolic.mapper.WalkMapper` for constructing
     persistent hash keys for use with
     :class:`pytools.persistent_dict.PersistentDict`.
     """

test/test_persistent_hash.py

@@ -0,0 +1,38 @@
+__copyright__ = "Copyright (C) 2023 University of Illinois Board of Trustees"
+
+__license__ = """
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in
+all copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
+THE SOFTWARE.
+"""
+
+
+from pymbolic.mapper.persistent_hash import PersistentHashWalkMapper
+
+
+def test_persistent_hash_simple() -> None:
+    from testlib import generate_random_expression
+    import hashlib
+    expr = generate_random_expression(seed=(333))
+
+    key_hash = hashlib.sha256()
+
+    phwm = PersistentHashWalkMapper(key_hash)
+    phwm(expr)
+
+    assert key_hash.hexdigest() == \
+        "1a1cd91483015333f2a9b06ab049a8edabc72aafc1f9b6d7cd831a39068e50da"