Add better type deduction to no-bool-literal-compare and `use-str-m…

…ethod` checks

refurb/checks/common.py

@@ -532,6 +532,9 @@ def get_mypy_type(node: Node) -> Type | None:
         case FloatExpr():
             return _get_builtin_mypy_type("float")
 
+        case NameExpr(fullname="builtins.True" | "builtins.False"):
+            return _get_builtin_mypy_type("bool")
+
         case DictExpr():
             return _get_builtin_mypy_type("dict")
 

refurb/checks/readability/no_is_bool_compare.py

@@ -1,8 +1,9 @@
 from dataclasses import dataclass
+from typing import TypeGuard
 
-from mypy.nodes import ComparisonExpr, Expression, NameExpr, Var
+from mypy.nodes import ComparisonExpr, Expression, NameExpr
 
-from refurb.checks.common import is_same_type, stringify
+from refurb.checks.common import get_mypy_type, is_same_type, stringify
 from refurb.error import Error
 
 
@@ -36,7 +37,7 @@ class ErrorInfo(Error):
     categories = ("logical", "readability", "truthy")
 
 
-def is_bool_literal(expr: Expression) -> bool:
+def is_bool_literal(expr: Expression) -> TypeGuard[NameExpr]:
     match expr:
         case NameExpr(fullname="builtins.True" | "builtins.False"):
             return True
@@ -45,11 +46,7 @@ def is_bool_literal(expr: Expression) -> bool:
 
 
 def is_bool_variable(expr: Expression) -> bool:
-    match expr:
-        case NameExpr(node=Var(type=ty)) if is_same_type(ty, bool):
-            return True
-
-    return False
+    return is_same_type(get_mypy_type(expr), bool)
 
 
 def is_truthy(oper: str, name: str) -> bool:
@@ -62,7 +59,7 @@ def check(node: ComparisonExpr, errors: list[Error]) -> None:
     match node:
         case ComparisonExpr(
             operators=["is" | "is not" | "==" | "!=" as oper],
-            operands=[NameExpr() as lhs, NameExpr() as rhs],
+            operands=[lhs, rhs],
         ):
             if is_bool_literal(lhs) and is_bool_variable(rhs):
                 expr = stringify(rhs)

refurb/checks/readability/use_str_method.py

@@ -1,9 +1,9 @@
 from dataclasses import dataclass
 from typing import Any
 
-from mypy.nodes import ArgKind, Block, CallExpr, LambdaExpr, MemberExpr, NameExpr, ReturnStmt, Var
+from mypy.nodes import ArgKind, Block, CallExpr, LambdaExpr, MemberExpr, NameExpr, ReturnStmt
 
-from refurb.checks.common import is_same_type, stringify
+from refurb.checks.common import get_mypy_type, is_same_type, stringify
 from refurb.error import Error
 
 
@@ -78,7 +78,7 @@ def check(node: LambdaExpr, errors: list[Error]) -> None:
                     ReturnStmt(
                         expr=CallExpr(
                             callee=MemberExpr(
-                                expr=NameExpr(name=member_base_name, node=Var(type=ty)),
+                                expr=NameExpr(name=member_base_name) as member_base,
                                 name=str_func_name,
                             ),
                             args=[],
@@ -89,7 +89,7 @@ def check(node: LambdaExpr, errors: list[Error]) -> None:
         ) if (
             arg_name == member_base_name
             and str_func_name in STR_FUNCS
-            and is_same_type(ty, str, None, Any)
+            and is_same_type(get_mypy_type(member_base), str, None, Any)
         ):
             msg = f"Replace `{stringify(node)}` with `str.{str_func_name}`"
 

test/data/err_149.py

@@ -16,6 +16,11 @@
 _ = True == b
 _ = False == b
 
+class Wrapper:
+    b: bool
+
+_ = Wrapper().b == True
+
 
 # these should not
 

test/data/err_149.txt

@@ -10,3 +10,4 @@ test/data/err_149.py:14:5 [FURB149]: Replace `b != True` with `not b`
 test/data/err_149.py:15:5 [FURB149]: Replace `b != False` with `b`
 test/data/err_149.py:16:5 [FURB149]: Replace `True == b` with `b`
 test/data/err_149.py:17:5 [FURB149]: Replace `False == b` with `not b`
+test/data/err_149.py:22:5 [FURB149]: Replace `Wrapper().b == True` with `Wrapper().b`