Implement B015 (#587)

README.md

@@ -467,6 +467,7 @@ The 🛠 emoji indicates that a rule is automatically fixable by the `--fix` com
 | B011 | DoNotAssertFalse | Do not `assert False` (`python -O` removes these calls), raise `AssertionError()` | 🛠 |
 | B013 | RedundantTupleInExceptionHandler | A length-one tuple literal is redundant. Write `except ValueError:` instead of `except (ValueError,):`. |  |
 | B014 | DuplicateHandlerException | Exception handler with duplicate exception: `ValueError` | 🛠 |
+| B015 | UselessComparison | Pointless comparison. This comparison does nothing but waste CPU instructions. Either prepend `assert` or remove it. |  |
 | B017 | NoAssertRaisesException | `assertRaises(Exception):` should be considered evil. |  |
 | B018 | UselessExpression | Found useless expression. Either assign it to a variable or remove it. |  |
 | B025 | DuplicateTryBlockException | try-except block with duplicate exception `Exception` |  |

resources/test/fixtures/B015.py

@@ -0,0 +1,24 @@
+assert 1 == 1
+
+1 == 1
+
+assert 1 in (1, 2)
+
+1 in (1, 2)
+
+
+if 1 == 2:
+    pass
+
+
+def test():
+    assert 1 in (1, 2)
+
+    1 in (1, 2)
+
+
+data = [x for x in [1, 2, 3] if x in (1, 2)]
+
+
+class TestClass:
+    1 == 1

src/check_ast.rs

@@ -1326,6 +1326,12 @@ where
                         self.locate_check(Range::from_located(expr)),
                     ));
                 }
+
+                if self.settings.enabled.contains(&CheckCode::B015) {
+                    if let Some(parent) = self.parents.last() {
+                        flake8_bugbear::plugins::useless_comparison(self, left, parent);
+                    }
+                }
             }
             ExprKind::Constant {
                 value: Constant::Str(value),

src/checks.rs

@@ -83,6 +83,7 @@ pub enum CheckCode {
     B011,
     B013,
     B014,
+    B015,
     B017,
     B018,
     B025,
@@ -298,6 +299,7 @@ pub enum CheckKind {
     DoNotAssertFalse,
     RedundantTupleInExceptionHandler(String),
     DuplicateHandlerException(Vec<String>),
+    UselessComparison,
     NoAssertRaisesException,
     UselessExpression,
     DuplicateTryBlockException(String),
@@ -484,6 +486,7 @@ impl CheckCode {
                 CheckKind::RedundantTupleInExceptionHandler("ValueError".to_string())
             }
             CheckCode::B014 => CheckKind::DuplicateHandlerException(vec!["ValueError".to_string()]),
+            CheckCode::B015 => CheckKind::UselessComparison,
             CheckCode::B017 => CheckKind::NoAssertRaisesException,
             CheckCode::B018 => CheckKind::UselessExpression,
             CheckCode::B025 => CheckKind::DuplicateTryBlockException("Exception".to_string()),
@@ -676,6 +679,7 @@ impl CheckCode {
             CheckCode::B011 => CheckCategory::Flake8Bugbear,
             CheckCode::B013 => CheckCategory::Flake8Bugbear,
             CheckCode::B014 => CheckCategory::Flake8Bugbear,
+            CheckCode::B015 => CheckCategory::Flake8Bugbear,
             CheckCode::B017 => CheckCategory::Flake8Bugbear,
             CheckCode::B018 => CheckCategory::Flake8Bugbear,
             CheckCode::B025 => CheckCategory::Flake8Bugbear,
@@ -835,6 +839,7 @@ impl CheckKind {
             CheckKind::DoNotAssertFalse => &CheckCode::B011,
             CheckKind::RedundantTupleInExceptionHandler(_) => &CheckCode::B013,
             CheckKind::DuplicateHandlerException(_) => &CheckCode::B014,
+            CheckKind::UselessComparison => &CheckCode::B015,
             CheckKind::NoAssertRaisesException => &CheckCode::B017,
             CheckKind::UselessExpression => &CheckCode::B018,
             CheckKind::DuplicateTryBlockException(_) => &CheckCode::B025,
@@ -1111,6 +1116,10 @@ impl CheckKind {
                      `except ({name},):`."
                 )
             }
+            CheckKind::UselessComparison => "Pointless comparison. This comparison does nothing \
+                                             but waste CPU instructions. Either prepend `assert` \
+                                             or remove it."
+                .to_string(),
             CheckKind::DuplicateHandlerException(names) => {
                 if names.len() == 1 {
                     let name = &names[0];

src/checks_gen.rs

@@ -23,6 +23,7 @@ pub enum CheckCodePrefix {
     B011,
     B013,
     B014,
+    B015,
     B017,
     B018,
     B02,
@@ -258,6 +259,7 @@ impl CheckCodePrefix {
                 CheckCode::B011,
                 CheckCode::B013,
                 CheckCode::B014,
+                CheckCode::B015,
                 CheckCode::B017,
                 CheckCode::B018,
                 CheckCode::B025,
@@ -277,16 +279,20 @@ impl CheckCodePrefix {
             CheckCodePrefix::B002 => vec![CheckCode::B002],
             CheckCodePrefix::B006 => vec![CheckCode::B006],
             CheckCodePrefix::B007 => vec![CheckCode::B007],
-            CheckCodePrefix::B01 => vec![
+            CheckCodePrefix::B01 => {
+                vec![
                     CheckCode::B011,
                     CheckCode::B013,
                     CheckCode::B014,
+                    CheckCode::B015,
                     CheckCode::B017,
                     CheckCode::B018,
-            ],
+                ]
+            }
             CheckCodePrefix::B011 => vec![CheckCode::B011],
             CheckCodePrefix::B013 => vec![CheckCode::B013],
             CheckCodePrefix::B014 => vec![CheckCode::B014],
+            CheckCodePrefix::B015 => vec![CheckCode::B015],
             CheckCodePrefix::B017 => vec![CheckCode::B017],
             CheckCodePrefix::B018 => vec![CheckCode::B018],
             CheckCodePrefix::B02 => vec![CheckCode::B025],
@@ -910,6 +916,7 @@ impl CheckCodePrefix {
             CheckCodePrefix::B011 => PrefixSpecificity::Explicit,
             CheckCodePrefix::B013 => PrefixSpecificity::Explicit,
             CheckCodePrefix::B014 => PrefixSpecificity::Explicit,
+            CheckCodePrefix::B015 => PrefixSpecificity::Explicit,
             CheckCodePrefix::B017 => PrefixSpecificity::Explicit,
             CheckCodePrefix::B018 => PrefixSpecificity::Explicit,
             CheckCodePrefix::B02 => PrefixSpecificity::Tens,

src/flake8_bugbear/plugins/mod.rs

@@ -5,6 +5,7 @@ pub use mutable_argument_default::mutable_argument_default;
 pub use redundant_tuple_in_exception_handler::redundant_tuple_in_exception_handler;
 pub use unary_prefix_increment::unary_prefix_increment;
 pub use unused_loop_control_variable::unused_loop_control_variable;
+pub use useless_comparison::useless_comparison;
 pub use useless_expression::useless_expression;
 
 mod assert_false;
@@ -14,4 +15,5 @@ mod mutable_argument_default;
 mod redundant_tuple_in_exception_handler;
 mod unary_prefix_increment;
 mod unused_loop_control_variable;
+mod useless_comparison;
 mod useless_expression;

src/flake8_bugbear/plugins/useless_comparison.rs

@@ -0,0 +1,14 @@
+use rustpython_ast::{Expr, Stmt, StmtKind};
+
+use crate::ast::types::{CheckLocator, Range};
+use crate::check_ast::Checker;
+use crate::checks::{Check, CheckKind};
+
+pub fn useless_comparison(checker: &mut Checker, expr: &Expr, parent: &Stmt) {
+    if let StmtKind::Expr { .. } = &parent.node {
+        checker.add_check(Check::new(
+            CheckKind::UselessComparison,
+            checker.locate_check(Range::from_located(expr)),
+        ));
+    }
+}

src/linter.rs

@@ -298,6 +298,7 @@ mod tests {
     #[test_case(CheckCode::B011, Path::new("B011.py"); "B011")]
     #[test_case(CheckCode::B013, Path::new("B013.py"); "B013")]
     #[test_case(CheckCode::B014, Path::new("B014.py"); "B014")]
+    #[test_case(CheckCode::B015, Path::new("B015.py"); "B015")]
     #[test_case(CheckCode::B017, Path::new("B017.py"); "B017")]
     #[test_case(CheckCode::B018, Path::new("B018.py"); "B018")]
     #[test_case(CheckCode::B025, Path::new("B025.py"); "B025")]

src/snapshots/ruff__linter__tests__B015_B015.py.snap

@@ -0,0 +1,37 @@
+---
+source: src/linter.rs
+expression: checks
+---
+- kind: UselessComparison
+  location:
+    row: 3
+    column: 0
+  end_location:
+    row: 3
+    column: 1
+  fix: ~
+- kind: UselessComparison
+  location:
+    row: 7
+    column: 0
+  end_location:
+    row: 7
+    column: 1
+  fix: ~
+- kind: UselessComparison
+  location:
+    row: 17
+    column: 4
+  end_location:
+    row: 17
+    column: 5
+  fix: ~
+- kind: UselessComparison
+  location:
+    row: 24
+    column: 4
+  end_location:
+    row: 24
+    column: 5
+  fix: ~
+