Add tests for #8192, #8893, #9642, #9689, #9815, #9941 (#9981)

Author: nickdrozd

tests/functional/u/unnecessary/unnecessary_lambda.py

@@ -1,4 +1,4 @@
-# pylint: disable=undefined-variable, use-list-literal, unnecessary-lambda-assignment, use-dict-literal
+# pylint: disable=undefined-variable, use-list-literal, unnecessary-lambda-assignment, use-dict-literal, disallowed-name
 """test suspicious lambda expressions
 """
 
@@ -65,3 +65,23 @@ def f(d):
 _ = lambda x: x(x)
 _ = lambda x, y: x(x, y)
 _ = lambda x: z(lambda y: x + y)(x)
+
+
+# https://github.com/pylint-dev/pylint/issues/8192
+
+# foo does not yet exist, so replacing lambda x: foo.get(x) with
+# foo.get will raise NameError
+g = lambda x: foo.get(x)  # [unnecessary-lambda]  FALSE POSITIVE
+
+# an object is created and given the name 'foo'
+foo = {1: 2}
+assert g(1) == 2
+
+# a new object is created and given the name 'foo'; first object is lost
+foo = {1: 3}
+assert g(1) == 3
+
+# the name 'foo' is deleted; second object is lost; there is no foo
+del foo
+
+assert g(1) == 3  # NameError: name 'foo' is not defined

tests/functional/u/unnecessary/unnecessary_lambda.txt

@@ -7,3 +7,4 @@ unnecessary-lambda:23:4:23:53:<lambda>:Lambda may not be necessary:UNDEFINED
 unnecessary-lambda:25:4:25:71:<lambda>:Lambda may not be necessary:UNDEFINED
 unnecessary-lambda:29:4:29:31:<lambda>:Lambda may not be necessary:UNDEFINED
 unnecessary-lambda:31:4:31:44:<lambda>:Lambda may not be necessary:UNDEFINED
+unnecessary-lambda:74:4:74:24:<lambda>:Lambda may not be necessary:UNDEFINED

tests/functional/u/used/used_before_assignment.py

@@ -1,5 +1,5 @@
 """Miscellaneous used-before-assignment cases"""
-# pylint: disable=consider-using-f-string, missing-function-docstring
+# pylint: disable=consider-using-f-string, missing-function-docstring, bare-except
 import datetime
 import sys
 from typing import NoReturn
@@ -222,3 +222,62 @@ def print_platform_specific_command(self):
             self.skip("only runs on Linux/Windows")
 
         print(cmd)
+
+
+# https://github.com/pylint-dev/pylint/issues/9941
+try:
+    x = 1 / 0
+except ZeroDivisionError:
+    print(x)  # [used-before-assignment]
+
+try:
+    y = 1 / 0
+    print(y)
+except ZeroDivisionError:
+    print(y)  # FALSE NEGATIVE
+
+
+# https://github.com/pylint-dev/pylint/issues/9642
+def __():
+    for i in []:
+        if i:
+            fail1 = 42
+    print(fail1)  # [possibly-used-before-assignment]
+
+    for i in []:
+        fail2 = 42
+    print(fail2)  # FALSE NEGATIVE
+
+
+# https://github.com/pylint-dev/pylint/issues/9689
+def outer_():
+    a = 1
+
+    def inner_try():
+        try:
+            nonlocal a
+            print(a)  # [used-before-assignment] FALSE POSITIVE
+            a = 2
+            print(a)
+        except:
+            pass
+
+    def inner_while():
+        i = 0
+        while i < 2:
+            i += 1
+            nonlocal a
+            print(a)  # [used-before-assignment] FALSE POSITIVE
+            a = 2
+            print(a)
+
+    def inner_for():
+        for _ in range(2):
+            nonlocal a
+            print(a)
+            a = 2
+            print(a)
+
+    inner_try()
+    inner_while()
+    inner_for()

tests/functional/u/used/used_before_assignment.txt

@@ -13,3 +13,7 @@ possibly-used-before-assignment:121:6:121:11::Possibly using variable 'VAR12' be
 used-before-assignment:152:10:152:14::Using variable 'SALE' before assignment:INFERENCE
 used-before-assignment:184:10:184:18::Using variable 'ALL_DONE' before assignment:INFERENCE
 used-before-assignment:195:6:195:24::Using variable 'NOT_ALWAYS_DEFINED' before assignment:INFERENCE
+used-before-assignment:231:10:231:11::Using variable 'x' before assignment:CONTROL_FLOW
+possibly-used-before-assignment:245:10:245:15:__:Possibly using variable 'fail1' before assignment:CONTROL_FLOW
+used-before-assignment:259:18:259:19:outer_.inner_try:Using variable 'a' before assignment:HIGH
+used-before-assignment:270:18:270:19:outer_.inner_while:Using variable 'a' before assignment:HIGH

tests/functional/u/used/used_before_assignment_postponed_evaluation.py

@@ -1,5 +1,5 @@
 """Tests for used-before-assignment when postponed evaluation of annotations is enabled"""
-# pylint: disable=missing-function-docstring, invalid-name
+# pylint: disable=missing-function-docstring, invalid-name, missing-class-docstring, too-few-public-methods
 from __future__ import annotations
 from typing import TYPE_CHECKING
 
@@ -11,3 +11,29 @@
 
 def function_one(m: math):  # no error for annotations
     return m
+
+# https://github.com/pylint-dev/pylint/issues/8893
+if TYPE_CHECKING:
+    import datetime
+
+def f():
+    return datetime.datetime.now()  # [used-before-assignment]
+
+def g() -> datetime.datetime:
+    return datetime.datetime.now()  # FALSE NEGATIVE
+
+if TYPE_CHECKING:
+    class X:
+        pass
+
+def h():
+    return X()  # FALSE NEGATIVE
+
+def i() -> X:
+    return X()  # FALSE NEGATIVE
+
+if TYPE_CHECKING:
+    from mod import Y
+
+def j():
+    return {Y() for _ in range(1)}  # FALSE NEGATIVE

tests/functional/u/used/used_before_assignment_postponed_evaluation.txt

@@ -1 +1,2 @@
 used-before-assignment:10:6:10:9::Using variable 'var' before assignment:INFERENCE
+used-before-assignment:20:11:20:19:f:Using variable 'datetime' before assignment:INFERENCE

tests/functional/u/used/used_before_assignment_py310.py

@@ -5,3 +5,72 @@
         print("x used to cause used-before-assignment!")
     case _:
         print("good thing it doesn't now!")
+
+
+# pylint: disable = missing-function-docstring, redefined-outer-name, missing-class-docstring
+
+# https://github.com/pylint-dev/pylint/issues/9668
+from enum import Enum
+from pylint.constants import PY311_PLUS
+if PY311_PLUS:
+    from typing import assert_never  # pylint: disable=no-name-in-module
+else:
+    from typing_extensions import assert_never
+
+class Example(Enum):
+    FOO = 1
+    BAR = 2
+
+def check_value_if_then_match_return(example: Example, should_check: bool) -> str | None:
+    if should_check:
+        result = None
+    else:
+        match example:
+            case Example.FOO:
+                result = "foo"
+            case Example.BAR:
+                result = "bar"
+            case _:
+                return None
+
+    return result  # [possibly-used-before-assignment] FALSE POSITIVE
+
+def check_value_if_then_match_raise(example: Example, should_check: bool) -> str | None:
+    if should_check:
+        result = None
+    else:
+        match example:
+            case Example.FOO:
+                result = "foo"
+            case Example.BAR:
+                result = "bar"
+            case _:
+                raise ValueError("Not a valid enum")
+
+    return result  # [possibly-used-before-assignment] FALSE POSITIVE
+
+def check_value_if_then_match_assert_never(example: Example, should_check: bool) -> str | None:
+    if should_check:
+        result = None
+    else:
+        match example:
+            case Example.FOO:
+                result = "foo"
+            case Example.BAR:
+                result = "bar"
+            case _:
+                assert_never(example)
+
+    return result  # [possibly-used-before-assignment] FALSE POSITIVE
+
+def g(x):
+    if x is None:
+        y = 0
+    else:
+        match x:
+            case int():
+                y = x
+            case _:
+                raise TypeError(type(x))
+
+    return y  # [possibly-used-before-assignment] FALSE POSITIVE

tests/functional/u/used/used_before_assignment_py310.txt

@@ -0,0 +1,4 @@
+possibly-used-before-assignment:36:11:36:17:check_value_if_then_match_return:Possibly using variable 'result' before assignment:CONTROL_FLOW
+possibly-used-before-assignment:50:11:50:17:check_value_if_then_match_raise:Possibly using variable 'result' before assignment:CONTROL_FLOW
+possibly-used-before-assignment:64:11:64:17:check_value_if_then_match_assert_never:Possibly using variable 'result' before assignment:CONTROL_FLOW
+possibly-used-before-assignment:76:11:76:12:g:Possibly using variable 'y' before assignment:CONTROL_FLOW

tests/functional/u/used/used_before_assignment_py312.py

@@ -4,3 +4,11 @@
 type Point[T] = tuple[T, ...]
 type Alias[*Ts] = tuple[*Ts]
 type Alias[**P] = Callable[P]
+
+# pylint: disable = invalid-name, missing-class-docstring, too-few-public-methods
+
+# https://github.com/pylint-dev/pylint/issues/9815
+type IntOrX = int | X  # [used-before-assignment] FALSE POSITIVE
+
+class X:
+    pass

tests/functional/u/used/used_before_assignment_py312.txt

@@ -0,0 +1 @@
+used-before-assignment:11:20:11:21::Using variable 'X' before assignment:HIGH