Add EnsureHashAlgorithm

changelog.d/20231021_102012_michael.hanke_ensurehash.md

@@ -0,0 +1,6 @@
+### 💫 Enhancements and new features
+
+- New `EnsureHashAlgorithm` constraint to automatically expose
+  and verify algorithm labels from `hashlib.algorithms_guaranteed`
+  Fixes https://github.com/datalad/datalad-next/issues/346 via
+  https://github.com/datalad/datalad-next/pull/492 (by @mslw @adswa)

datalad_next/commands/ls_file_collection.py

@@ -39,6 +39,8 @@
     EnsureChoice,
     EnsurePath,
     EnsureURL,
+    EnsureHashAlgorithm,
+    EnsureListOf,
 )
 from datalad_next.uis import (
     ansi_colors as ac,
@@ -93,9 +95,7 @@ def __init__(self):
             param_constraints=dict(
                 type=self._collection_types,
                 collection=EnsurePath(lexists=True) | EnsureURL(),
-                # TODO EnsureHashAlgorithm
-                # https://github.com/datalad/datalad-next/issues/346
-                #hash=None,
+                hash=EnsureHashAlgorithm() | EnsureListOf(EnsureHashAlgorithm()),
             ),
             joint_constraints={
                 ParameterConstraintContext(('type', 'collection', 'hash'),

datalad_next/constraints/__init__.py

@@ -59,6 +59,7 @@
     EnsureCallable,
     EnsureChoice,
     EnsureFloat,
+    EnsureHashAlgorithm,
     EnsureInt,
     EnsureKeyChoice,
     EnsureNone,

datalad_next/constraints/basic.py

@@ -12,6 +12,7 @@
 
 __docformat__ = 'restructuredtext'
 
+from hashlib import algorithms_guaranteed as hash_algorithms_guaranteed
 from pathlib import Path
 import re
 
@@ -274,6 +275,9 @@ def long_description(self):
     def short_description(self):
         return '{%s}' % ', '.join([repr(c) for c in self._allowed])
 
+    def __str__(self):
+        return f"one of {self.short_description()}"
+
 
 class EnsureKeyChoice(EnsureChoice):
     """Ensure value under a key in an input is in a set of possible values"""
@@ -497,3 +501,12 @@ def short_description(self):
             if self._ref
             else '',
         )
+
+
+class EnsureHashAlgorithm(EnsureChoice):
+    """Ensure an input matches a name of a ``hashlib`` algorithm
+
+    Specifically the item must be in the ``algorithms_guaranteed`` collection.
+    """
+    def __init__(self):
+        super().__init__(*hash_algorithms_guaranteed)

datalad_next/constraints/compound.py

@@ -77,10 +77,12 @@ def __call__(self, value):
             iter = self._iter_type(
                 self._item_constraint(i) for i in value
             )
-        except TypeError as e:
+        except (ConstraintError, TypeError) as e:
             self.raise_for(
                 value,
-                "cannot coerce to target (item) type",
+                "{itertype} item is not {itype}",
+                itertype=self._iter_type.__name__,
+                itype=self._item_constraint,
                 __caused_by__=e,
             )
         if self._min_len is not None or self._max_len is not None:

datalad_next/constraints/tests/test_basic.py

@@ -11,6 +11,7 @@
     EnsureNone,
     EnsureCallable,
     EnsureChoice,
+    EnsureHashAlgorithm,
     EnsureKeyChoice,
     EnsureRange,
     EnsurePath,
@@ -188,6 +189,7 @@ def test_choice():
         assert i in descr
     # short is a "set" or repr()s
     assert c.short_description() == "{'choice1', 'choice2', None}"
+    assert str(c) == "one of {'choice1', 'choice2', None}"
     # this should always work
     assert c('choice1') == 'choice1'
     assert c(None) is None
@@ -317,3 +319,27 @@ def test_EnsurePath_fordataset(existing_dataset):
     # 2. dataset is given as a dataset object
     tc = c.for_dataset(DatasetParameter(ds, ds))
     assert tc('relpath') == (ds.pathobj / 'relpath')
+
+
+def test_EnsureHashAlgorithm():
+    c = EnsureHashAlgorithm()
+    # simple cases that should pass
+    hashes = [
+        'sha3_256', 'shake_256', 'sha3_384', 'md5', 'shake_128', 'sha384',
+        'sha3_224', 'blake2s', 'sha1', 'blake2b', 'sha224', 'sha512', 'sha256',
+        'sha3_512'
+    ]
+    for hash in hashes:
+        c(hash)
+    # a few bogus ones:
+    bad_hashes = [
+        'md17', 'McGyver', 'sha2', 'bogus'
+    ]
+    for baddie in bad_hashes:
+        with pytest.raises(ConstraintError):
+            c(baddie)
+
+    # check messaging
+    for i in ('md5', 'shake_256', 'sha3_512'):
+        assert i in c.short_description()
+        assert i in c.long_description()