Add simplify-hashlib-ctor check:

Also bump version for new release.

docs/checks.md

@@ -2124,11 +2124,39 @@ Use `.hexdigest()` to get a hex digest from a hash.
 Bad:
 
 ```python
+from hashlib import sha512
+
 hashed = sha512(b"some data").digest().hex()
 ```
 
 Good:
 
 ```python
+from hashlib import sha512
+
 hashed = sha512(b"some data").hexdigest()
+```
+
+## FURB182: `simplify-hashlib-ctor`
+
+Categories: `hashlib` `readability`
+
+You can pass data into `hashlib` constructors, so instead of creating a
+hash object and immediately updating it, pass the data directly.
+
+Bad:
+
+```python
+from hashlib import sha512
+
+h = sha512()
+h.update(b"data)
+```
+
+Good:
+
+```python
+from hashlib import sha512
+
+h = sha512(b"data")
 ```

pyproject.toml

@@ -1,6 +1,6 @@
 [tool.poetry]
 name = "refurb"
-version = "1.23.0"
+version = "1.24.0"
 description = "A tool for refurbish and modernize Python codebases"
 authors = ["dosisod"]
 license = "GPL-3.0-only"

refurb/checks/hashlib/simplify_ctor.py

@@ -0,0 +1,88 @@
+from dataclasses import dataclass
+from typing import cast
+
+from mypy.nodes import (
+    AssignmentStmt,
+    Block,
+    CallExpr,
+    ExpressionStmt,
+    MemberExpr,
+    MypyFile,
+    NameExpr,
+    RefExpr,
+    Statement,
+)
+
+from refurb.checks.common import check_block_like, stringify
+from refurb.checks.hashlib.use_hexdigest import HASHLIB_ALGOS
+from refurb.error import Error
+
+
+@dataclass
+class ErrorInfo(Error):
+    """
+    You can pass data into `hashlib` constructors, so instead of creating a
+    hash object and immediately updating it, pass the data directly.
+
+    Bad:
+
+    ```
+    from hashlib import sha512
+
+    h = sha512()
+    h.update(b"data)
+    ```
+
+    Good:
+
+    ```
+    from hashlib import sha512
+
+    h = sha512(b"data")
+    ```
+    """
+
+    name = "simplify-hashlib-ctor"
+    categories = ("hashlib", "readability")
+    code = 182
+
+
+def check(node: Block | MypyFile, errors: list[Error]) -> None:
+    check_block_like(check_stmts, node, errors)
+
+
+def check_stmts(stmts: list[Statement], errors: list[Error]) -> None:
+    assignment: AssignmentStmt | None = None
+    var: RefExpr | None = None
+
+    for stmt in stmts:
+        match stmt:
+            case AssignmentStmt(
+                lvalues=[NameExpr() as lhs],
+                rvalue=CallExpr(callee=RefExpr(fullname=fn), args=[]),
+            ) if fn in HASHLIB_ALGOS:
+                assignment = stmt
+                var = lhs
+
+            case ExpressionStmt(
+                expr=CallExpr(
+                    callee=MemberExpr(
+                        expr=RefExpr(fullname=fullname, name=lhs),  # type: ignore
+                        name="update",
+                    ),
+                    args=[arg],
+                )
+            ) if assignment and var and var.fullname == fullname:
+                func_name = stringify(cast(CallExpr, assignment.rvalue).callee)
+
+                data = stringify(arg)
+
+                old = f"{lhs} = {func_name}(); {lhs}.update({data})"
+                new = f"{lhs} = {func_name}({data})"
+
+                msg = f"Replace `{old}` with `{new}`"
+
+                errors.append(ErrorInfo.from_node(assignment, msg))
+
+            case _:
+                assignment = None

refurb/checks/hashlib/use_hexdigest.py

@@ -14,12 +14,16 @@ class ErrorInfo(Error):
     Bad:
 
     ```
+    from hashlib import sha512
+
     hashed = sha512(b"some data").digest().hex()
     ```
 
     Good:
 
     ```
+    from hashlib import sha512
+
     hashed = sha512(b"some data").hexdigest()
     ```
     """

test/data/err_182.py

@@ -0,0 +1,87 @@
+import hashlib
+from hashlib import (
+    blake2b,
+    blake2s,
+    md5,
+    sha1,
+    sha3_224,
+    sha3_256,
+    sha3_384,
+    sha3_512,
+    sha224,
+)
+from hashlib import sha256
+from hashlib import sha256 as hash_algo
+from hashlib import sha384, sha512, shake_128, shake_256
+
+# these will match
+
+h1 = blake2b()
+h1.update(b"data")
+
+h2 = blake2s()
+h2.update(b"data")
+
+h3 = md5()
+h3.update(b"data")
+
+h4 = sha1()
+h4.update(b"data")
+
+h5 = sha224()
+h5.update(b"data")
+
+h6 = sha256()
+h6.update(b"data")
+
+h7 = sha384()
+h7.update(b"data")
+
+h8 = sha3_224()
+h8.update(b"data")
+
+h9 = sha3_256()
+h9.update(b"data")
+
+h10 = sha3_384()
+h10.update(b"data")
+
+h11 = sha3_512()
+h11.update(b"data")
+
+h12 = sha512()
+h12.update(b"data")
+
+h13 = shake_128()
+h13.update(b"data")
+
+h14 = shake_256()
+h14.update(b"data")
+
+h15 = hashlib.sha256()
+h15.update(b"data")
+
+h16 = hash_algo()
+h16.update(b"data")
+
+
+# these will not
+
+h17 = sha256()
+h17.digest()
+
+h18 = sha256(b"data")
+h18.update(b"more data")
+h18.digest()
+
+h19 = sha256()
+pass
+h19.digest()
+
+class Hash:
+    def update(self, data: bytes) -> None:
+        return None
+
+
+h20 = Hash()
+h20.update(b"data")

test/data/err_182.txt

@@ -0,0 +1,16 @@
+test/data/err_182.py:19:1 [FURB182]: Replace `h1 = blake2b(); h1.update(b'data')` with `h1 = blake2b(b'data')`
+test/data/err_182.py:22:1 [FURB182]: Replace `h2 = blake2s(); h2.update(b'data')` with `h2 = blake2s(b'data')`
+test/data/err_182.py:25:1 [FURB182]: Replace `h3 = md5(); h3.update(b'data')` with `h3 = md5(b'data')`
+test/data/err_182.py:28:1 [FURB182]: Replace `h4 = sha1(); h4.update(b'data')` with `h4 = sha1(b'data')`
+test/data/err_182.py:31:1 [FURB182]: Replace `h5 = sha224(); h5.update(b'data')` with `h5 = sha224(b'data')`
+test/data/err_182.py:34:1 [FURB182]: Replace `h6 = sha256(); h6.update(b'data')` with `h6 = sha256(b'data')`
+test/data/err_182.py:37:1 [FURB182]: Replace `h7 = sha384(); h7.update(b'data')` with `h7 = sha384(b'data')`
+test/data/err_182.py:40:1 [FURB182]: Replace `h8 = sha3_224(); h8.update(b'data')` with `h8 = sha3_224(b'data')`
+test/data/err_182.py:43:1 [FURB182]: Replace `h9 = sha3_256(); h9.update(b'data')` with `h9 = sha3_256(b'data')`
+test/data/err_182.py:46:1 [FURB182]: Replace `h10 = sha3_384(); h10.update(b'data')` with `h10 = sha3_384(b'data')`
+test/data/err_182.py:49:1 [FURB182]: Replace `h11 = sha3_512(); h11.update(b'data')` with `h11 = sha3_512(b'data')`
+test/data/err_182.py:52:1 [FURB182]: Replace `h12 = sha512(); h12.update(b'data')` with `h12 = sha512(b'data')`
+test/data/err_182.py:55:1 [FURB182]: Replace `h13 = shake_128(); h13.update(b'data')` with `h13 = shake_128(b'data')`
+test/data/err_182.py:58:1 [FURB182]: Replace `h14 = shake_256(); h14.update(b'data')` with `h14 = shake_256(b'data')`
+test/data/err_182.py:61:1 [FURB182]: Replace `h15 = hashlib.sha256(); h15.update(b'data')` with `h15 = hashlib.sha256(b'data')`
+test/data/err_182.py:64:1 [FURB182]: Replace `h16 = hash_algo(); h16.update(b'data')` with `h16 = hash_algo(b'data')`