hashutil: drop all pre-3.6 blake2 workarounds

blake2s and blake2b have been provided by the stdlib hashlib since
Python 3.6, and we declare 3.7 as minimum Python version supported.

mypy.ini

@@ -22,8 +22,5 @@ ignore_missing_imports = True
 [mypy-pkg_resources.*]
 ignore_missing_imports = True
 
-[mypy-pyblake2.*]
-ignore_missing_imports = True
-
 [mypy-pytest.*]
 ignore_missing_imports = True

setup.py

@@ -35,8 +35,6 @@ def parse_requirements(name=None):
     return requirements
 
 
-blake2_requirements = ['pyblake2;python_version<"3.6"']
-
 setup(
     name="swh.model",
     description="Software Heritage data model",
@@ -49,9 +47,7 @@ setup(
     packages=find_packages(),
     setup_requires=["setuptools-scm"],
     use_scm_version=True,
-    install_requires=(
-        parse_requirements() + parse_requirements("swh") + blake2_requirements
-    ),
+    install_requires=parse_requirements() + parse_requirements("swh"),
     extras_require={
         "cli": parse_requirements("cli"),
         "testing-minimal": parse_requirements("test"),

swh/model/hashutil.py

@@ -183,20 +183,8 @@ def _new_blake2_hash(algo):
                 "Digest size for algorithm %s must be a multiple of 8" % algo
             )
 
-    if lalgo in hashlib.algorithms_available:
-        # Handle the case where OpenSSL ships the given algorithm
-        # (e.g. Python 3.5 on Debian 9 stretch)
-        _blake2_hash_cache[algo] = lambda: hashlib.new(lalgo)
-    else:
-        # Try using the built-in implementation for Python 3.6+
-        if blake_family in hashlib.algorithms_available:
-            blake2 = getattr(hashlib, blake_family)
-        else:
-            import pyblake2
-
-            blake2 = getattr(pyblake2, blake_family)
-
-        _blake2_hash_cache[algo] = lambda: blake2(digest_size=digest_size)
+    blake2 = getattr(hashlib, blake_family)
+    _blake2_hash_cache[algo] = lambda: blake2(digest_size=digest_size)
 
     return _blake2_hash_cache[algo]()
 

swh/model/tests/test_hashutil.py

@@ -213,86 +213,8 @@ def test_new_hash_unsupported_hashing_algorithm():
         hashutil._new_hash("blake2:10")
 
 
-@pytest.mark.skipif(
-    "blake2b512" not in hashlib.algorithms_available, reason="blake2b512 not built-in"
-)
-@patch("hashlib.new")
-def test_new_hash_blake2b_blake2b512_builtin(mock_hashlib_new):
-    mock_hashlib_new.return_value = sentinel = object()
-
-    h = hashutil._new_hash("blake2b512")
-
-    assert h is sentinel
-    mock_hashlib_new.assert_called_with("blake2b512")
-
-
-@pytest.mark.skipif(
-    "blake2s256" not in hashlib.algorithms_available, reason="blake2s256 not built-in"
-)
-@patch("hashlib.new")
-def test_new_hash_blake2s_blake2s256_builtin(mock_hashlib_new):
-    mock_hashlib_new.return_value = sentinel = object()
-
-    h = hashutil._new_hash("blake2s256")
-
-    assert h is sentinel
-    mock_hashlib_new.assert_called_with("blake2s256")
-
-
-@pytest.mark.skipif(
-    "blake2b" not in hashlib.algorithms_available, reason="blake2b not built-in"
-)
 def test_new_hash_blake2b_builtin():
-    removed_hash = False
-
-    try:
-        if "blake2b512" in hashlib.algorithms_available:
-            removed_hash = True
-            hashlib.algorithms_available.remove("blake2b512")
-
-        with patch_blake2("hashlib.blake2b") as mock_blake2b:
-            mock_blake2b.return_value = sentinel = object()
-
-            h = hashutil._new_hash("blake2b512")
-
-            assert h is sentinel
-            mock_blake2b.assert_called_with(digest_size=512 // 8)
-    finally:
-        if removed_hash:
-            hashlib.algorithms_available.add("blake2b512")
-
-
-@pytest.mark.skipif(
-    "blake2s" not in hashlib.algorithms_available, reason="blake2s not built-in"
-)
-def test_new_hash_blake2s_builtin():
-    removed_hash = False
-
-    try:
-        if "blake2s256" in hashlib.algorithms_available:
-            removed_hash = True
-            hashlib.algorithms_available.remove("blake2s256")
-
-        with patch_blake2("hashlib.blake2s") as mock_blake2s:
-            mock_blake2s.return_value = sentinel = object()
-
-            h = hashutil._new_hash("blake2s256")
-
-            assert h is sentinel
-            mock_blake2s.assert_called_with(digest_size=256 // 8)
-    finally:
-        if removed_hash:
-            hashlib.algorithms_available.add("blake2s256")
-
-
-@pytest.mark.skipif(
-    "blake2b512" in hashlib.algorithms_available, reason="blake2b512 built-in"
-)
-@pytest.mark.skipif(
-    "blake2b" in hashlib.algorithms_available, reason="blake2b built-in"
-)
-def test_new_hash_blake2b_pyblake2():
-    with patch_blake2("pyblake2.blake2b") as mock_blake2b:
+    with patch_blake2("hashlib.blake2b") as mock_blake2b:
         mock_blake2b.return_value = sentinel = object()
 
         h = hashutil._new_hash("blake2b512")
@@ -301,14 +223,8 @@ def test_new_hash_blake2b_pyblake2():
         mock_blake2b.assert_called_with(digest_size=512 // 8)
 
 
-@pytest.mark.skipif(
-    "blake2s256" in hashlib.algorithms_available, reason="blake2s256 built-in"
-)
-@pytest.mark.skipif(
-    "blake2s" in hashlib.algorithms_available, reason="blake2s built-in"
-)
-def test_new_hash_blake2s_pyblake2():
-    with patch_blake2("pyblake2.blake2s") as mock_blake2s:
+def test_new_hash_blake2s_builtin():
+    with patch_blake2("hashlib.blake2s") as mock_blake2s:
         mock_blake2s.return_value = sentinel = object()
 
         h = hashutil._new_hash("blake2s256")