Avoid B015,B018 for last expression in a cell (#8815)

## Summary

This PR updates `B015` and `B018` to ignore last top-level expressions
in each cell of a Jupyter Notebook.

Part of #8669

## Test Plan

Add test cases for both rules and update the snapshots.
This commit is contained in:
Dhruv Manilawala 2023-11-22 09:33:23 -06:00 committed by GitHub
parent 727e389cac
commit 5b726f70f4
No known key found for this signature in database
GPG key ID: 4AEE18F83AFDEB23
11 changed files with 454 additions and 1 deletions

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@ -0,0 +1,149 @@
{
"cells": [
{
"cell_type": "code",
"execution_count": 1,
"id": "33faf7ad-a3fd-4ac4-a0c3-52e507ed49df",
"metadata": {},
"outputs": [],
"source": [
"x = 1"
]
},
{
"cell_type": "code",
"execution_count": 2,
"id": "481fb4bf-c1b9-47da-927f-3cfdfe4b49ec",
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"True"
]
},
"execution_count": 2,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"# Simple case\n",
"x == 1"
]
},
{
"cell_type": "code",
"execution_count": 3,
"id": "2f0c65a5-0a0e-4080-afce-5a8ed0d706df",
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"True"
]
},
"execution_count": 3,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"# Only skip the last expression\n",
"x == 1 # B018\n",
"x == 1"
]
},
{
"cell_type": "code",
"execution_count": 4,
"id": "5a3fd75d-26d9-44f7-b013-1684aabfd0ae",
"metadata": {},
"outputs": [],
"source": [
"# Nested expressions isn't relevant\n",
"if True:\n",
" x == 1"
]
},
{
"cell_type": "code",
"execution_count": 5,
"id": "e00e1afa-b76c-4774-be2a-7223641579e4",
"metadata": {},
"outputs": [],
"source": [
"# Semicolons shouldn't affect the output\n",
"x == 1;"
]
},
{
"cell_type": "code",
"execution_count": 6,
"id": "05eab5b9-e2ba-4954-8ef3-b035a79573fe",
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"True"
]
},
"execution_count": 6,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"# Semicolons with multiple expressions\n",
"x == 1; x == 1"
]
},
{
"cell_type": "code",
"execution_count": 7,
"id": "9cbbddc5-83fc-4fdb-81ab-53a3912ae898",
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"True"
]
},
"execution_count": 7,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"# Comments, newlines and whitespace\n",
"x == 1 # comment\n",
"\n",
"# another comment"
]
}
],
"metadata": {
"kernelspec": {
"display_name": "Python (ruff-playground)",
"language": "python",
"name": "ruff-playground"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 3
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
"version": "3.11.3"
}
},
"nbformat": 4,
"nbformat_minor": 5
}

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@ -0,0 +1,149 @@
{
"cells": [
{
"cell_type": "code",
"execution_count": 1,
"id": "33faf7ad-a3fd-4ac4-a0c3-52e507ed49df",
"metadata": {},
"outputs": [],
"source": [
"x = 1"
]
},
{
"cell_type": "code",
"execution_count": 2,
"id": "481fb4bf-c1b9-47da-927f-3cfdfe4b49ec",
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"1"
]
},
"execution_count": 2,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"# Simple case\n",
"x"
]
},
{
"cell_type": "code",
"execution_count": 3,
"id": "2f0c65a5-0a0e-4080-afce-5a8ed0d706df",
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"1"
]
},
"execution_count": 3,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"# Only skip the last expression\n",
"x # B018\n",
"x"
]
},
{
"cell_type": "code",
"execution_count": 4,
"id": "5a3fd75d-26d9-44f7-b013-1684aabfd0ae",
"metadata": {},
"outputs": [],
"source": [
"# Nested expressions isn't relevant\n",
"if True:\n",
" x"
]
},
{
"cell_type": "code",
"execution_count": 5,
"id": "e00e1afa-b76c-4774-be2a-7223641579e4",
"metadata": {},
"outputs": [],
"source": [
"# Semicolons shouldn't affect the output\n",
"x;"
]
},
{
"cell_type": "code",
"execution_count": 6,
"id": "05eab5b9-e2ba-4954-8ef3-b035a79573fe",
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"1"
]
},
"execution_count": 6,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"# Semicolons with multiple expressions\n",
"x; x"
]
},
{
"cell_type": "code",
"execution_count": 7,
"id": "9cbbddc5-83fc-4fdb-81ab-53a3912ae898",
"metadata": {},
"outputs": [
{
"data": {
"text/plain": [
"1"
]
},
"execution_count": 7,
"metadata": {},
"output_type": "execute_result"
}
],
"source": [
"# Comments, newlines and whitespace\n",
"x # comment\n",
"\n",
"# another comment"
]
}
],
"metadata": {
"kernelspec": {
"display_name": "Python (ruff-playground)",
"language": "python",
"name": "ruff-playground"
},
"language_info": {
"codemirror_mode": {
"name": "ipython",
"version": 3
},
"file_extension": ".py",
"mimetype": "text/x-python",
"name": "python",
"nbconvert_exporter": "python",
"pygments_lexer": "ipython3",
"version": "3.11.3"
}
},
"nbformat": 4,
"nbformat_minor": 5
}

View file

@ -37,6 +37,7 @@ use ruff_python_ast::{
use ruff_text_size::{Ranged, TextRange, TextSize}; use ruff_text_size::{Ranged, TextRange, TextSize};
use ruff_diagnostics::{Diagnostic, IsolationLevel}; use ruff_diagnostics::{Diagnostic, IsolationLevel};
use ruff_notebook::CellOffsets;
use ruff_python_ast::all::{extract_all_names, DunderAllFlags}; use ruff_python_ast::all::{extract_all_names, DunderAllFlags};
use ruff_python_ast::helpers::{ use ruff_python_ast::helpers::{
collect_import_from_member, extract_handled_exceptions, to_module_path, collect_import_from_member, extract_handled_exceptions, to_module_path,
@ -78,6 +79,8 @@ pub(crate) struct Checker<'a> {
module_path: Option<&'a [String]>, module_path: Option<&'a [String]>,
/// The [`PySourceType`] of the current file. /// The [`PySourceType`] of the current file.
pub(crate) source_type: PySourceType, pub(crate) source_type: PySourceType,
/// The [`CellOffsets`] for the current file, if it's a Jupyter notebook.
cell_offsets: Option<&'a CellOffsets>,
/// The [`flags::Noqa`] for the current analysis (i.e., whether to respect suppression /// The [`flags::Noqa`] for the current analysis (i.e., whether to respect suppression
/// comments). /// comments).
noqa: flags::Noqa, noqa: flags::Noqa,
@ -120,6 +123,7 @@ impl<'a> Checker<'a> {
indexer: &'a Indexer, indexer: &'a Indexer,
importer: Importer<'a>, importer: Importer<'a>,
source_type: PySourceType, source_type: PySourceType,
cell_offsets: Option<&'a CellOffsets>,
) -> Checker<'a> { ) -> Checker<'a> {
Checker { Checker {
settings, settings,
@ -137,6 +141,7 @@ impl<'a> Checker<'a> {
deferred: Deferred::default(), deferred: Deferred::default(),
diagnostics: Vec::default(), diagnostics: Vec::default(),
flake8_bugbear_seen: Vec::default(), flake8_bugbear_seen: Vec::default(),
cell_offsets,
} }
} }
} }
@ -225,6 +230,11 @@ impl<'a> Checker<'a> {
self.package self.package
} }
/// The [`CellOffsets`] for the current file, if it's a Jupyter notebook.
pub(crate) const fn cell_offsets(&self) -> Option<&'a CellOffsets> {
self.cell_offsets
}
/// Returns whether the given rule should be checked. /// Returns whether the given rule should be checked.
#[inline] #[inline]
pub(crate) const fn enabled(&self, rule: Rule) -> bool { pub(crate) const fn enabled(&self, rule: Rule) -> bool {
@ -1942,6 +1952,7 @@ pub(crate) fn check_ast(
path: &Path, path: &Path,
package: Option<&Path>, package: Option<&Path>,
source_type: PySourceType, source_type: PySourceType,
cell_offsets: Option<&CellOffsets>,
) -> Vec<Diagnostic> { ) -> Vec<Diagnostic> {
let module_path = package.and_then(|package| to_module_path(package, path)); let module_path = package.and_then(|package| to_module_path(package, path));
let module = Module { let module = Module {
@ -1970,6 +1981,7 @@ pub(crate) fn check_ast(
indexer, indexer,
Importer::new(python_ast, locator, stylist), Importer::new(python_ast, locator, stylist),
source_type, source_type,
cell_offsets,
); );
checker.bind_builtins(); checker.bind_builtins();

View file

@ -163,6 +163,7 @@ pub fn check_path(
path, path,
package, package,
source_type, source_type,
cell_offsets,
)); ));
} }
if use_imports { if use_imports {

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@ -0,0 +1,28 @@
use ruff_notebook::CellOffsets;
use ruff_python_semantic::SemanticModel;
use ruff_python_trivia::{SimpleTokenKind, SimpleTokenizer};
use ruff_source_file::Locator;
use ruff_text_size::{Ranged, TextRange};
/// Return `true` if the statement containing the current expression is the last
/// top-level expression in the cell. This assumes that the source is a Jupyter
/// Notebook.
pub(super) fn at_last_top_level_expression_in_cell(
semantic: &SemanticModel,
locator: &Locator,
cell_offsets: Option<&CellOffsets>,
) -> bool {
if !semantic.at_top_level() {
return false;
}
let current_statement_end = semantic.current_statement().end();
cell_offsets
.and_then(|cell_offsets| cell_offsets.containing_range(current_statement_end))
.is_some_and(|cell_range| {
SimpleTokenizer::new(
locator.contents(),
TextRange::new(current_statement_end, cell_range.end()),
)
.all(|token| token.kind() == SimpleTokenKind::Semi || token.kind().is_trivia())
})
}

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@ -1,4 +1,5 @@
//! Rules from [flake8-bugbear](https://pypi.org/project/flake8-bugbear/). //! Rules from [flake8-bugbear](https://pypi.org/project/flake8-bugbear/).
pub(crate) mod helpers;
pub(crate) mod rules; pub(crate) mod rules;
pub mod settings; pub mod settings;
@ -54,8 +55,10 @@ mod tests {
#[test_case(Rule::UnreliableCallableCheck, Path::new("B004.py"))] #[test_case(Rule::UnreliableCallableCheck, Path::new("B004.py"))]
#[test_case(Rule::UnusedLoopControlVariable, Path::new("B007.py"))] #[test_case(Rule::UnusedLoopControlVariable, Path::new("B007.py"))]
#[test_case(Rule::UselessComparison, Path::new("B015.py"))] #[test_case(Rule::UselessComparison, Path::new("B015.py"))]
#[test_case(Rule::UselessComparison, Path::new("B015.ipynb"))]
#[test_case(Rule::UselessContextlibSuppress, Path::new("B022.py"))] #[test_case(Rule::UselessContextlibSuppress, Path::new("B022.py"))]
#[test_case(Rule::UselessExpression, Path::new("B018.py"))] #[test_case(Rule::UselessExpression, Path::new("B018.py"))]
#[test_case(Rule::UselessExpression, Path::new("B018.ipynb"))]
fn rules(rule_code: Rule, path: &Path) -> Result<()> { fn rules(rule_code: Rule, path: &Path) -> Result<()> {
let snapshot = format!("{}_{}", rule_code.noqa_code(), path.to_string_lossy()); let snapshot = format!("{}_{}", rule_code.noqa_code(), path.to_string_lossy());
let diagnostics = test_path( let diagnostics = test_path(

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@ -5,6 +5,8 @@ use ruff_text_size::Ranged;
use crate::checkers::ast::Checker; use crate::checkers::ast::Checker;
use super::super::helpers::at_last_top_level_expression_in_cell;
/// ## What it does /// ## What it does
/// Checks for useless comparisons. /// Checks for useless comparisons.
/// ///
@ -41,6 +43,19 @@ impl Violation for UselessComparison {
/// B015 /// B015
pub(crate) fn useless_comparison(checker: &mut Checker, expr: &Expr) { pub(crate) fn useless_comparison(checker: &mut Checker, expr: &Expr) {
if expr.is_compare_expr() { if expr.is_compare_expr() {
// For Jupyter Notebooks, ignore the last top-level expression for each cell.
// This is because it's common to have a cell that ends with an expression
// to display it's value.
if checker.source_type.is_ipynb()
&& at_last_top_level_expression_in_cell(
checker.semantic(),
checker.locator(),
checker.cell_offsets(),
)
{
return;
}
checker checker
.diagnostics .diagnostics
.push(Diagnostic::new(UselessComparison, expr.range())); .push(Diagnostic::new(UselessComparison, expr.range()));

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@ -6,6 +6,8 @@ use ruff_text_size::Ranged;
use crate::checkers::ast::Checker; use crate::checkers::ast::Checker;
use super::super::helpers::at_last_top_level_expression_in_cell;
/// ## What it does /// ## What it does
/// Checks for useless expressions. /// Checks for useless expressions.
/// ///
@ -59,6 +61,19 @@ pub(crate) fn useless_expression(checker: &mut Checker, value: &Expr) {
return; return;
} }
// For Jupyter Notebooks, ignore the last top-level expression for each cell.
// This is because it's common to have a cell that ends with an expression
// to display it's value.
if checker.source_type.is_ipynb()
&& at_last_top_level_expression_in_cell(
checker.semantic(),
checker.locator(),
checker.cell_offsets(),
)
{
return;
}
// Ignore statements that have side effects. // Ignore statements that have side effects.
if contains_effect(value, |id| checker.semantic().is_builtin(id)) { if contains_effect(value, |id| checker.semantic().is_builtin(id)) {
// Flag attributes as useless expressions, even if they're attached to calls or other // Flag attributes as useless expressions, even if they're attached to calls or other

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@ -0,0 +1,34 @@
---
source: crates/ruff_linter/src/rules/flake8_bugbear/mod.rs
---
B015.ipynb:5:1: B015 Pointless comparison. Did you mean to assign a value? Otherwise, prepend `assert` or remove it.
|
3 | x == 1
4 | # Only skip the last expression
5 | x == 1 # B018
| ^^^^^^ B015
6 | x == 1
7 | # Nested expressions isn't relevant
|
B015.ipynb:9:5: B015 Pointless comparison. Did you mean to assign a value? Otherwise, prepend `assert` or remove it.
|
7 | # Nested expressions isn't relevant
8 | if True:
9 | x == 1
| ^^^^^^ B015
10 | # Semicolons shouldn't affect the output
11 | x == 1;
|
B015.ipynb:13:1: B015 Pointless comparison. Did you mean to assign a value? Otherwise, prepend `assert` or remove it.
|
11 | x == 1;
12 | # Semicolons with multiple expressions
13 | x == 1; x == 1
| ^^^^^^ B015
14 | # Comments, newlines and whitespace
15 | x == 1 # comment
|

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@ -0,0 +1,34 @@
---
source: crates/ruff_linter/src/rules/flake8_bugbear/mod.rs
---
B018.ipynb:5:1: B018 Found useless expression. Either assign it to a variable or remove it.
|
3 | x
4 | # Only skip the last expression
5 | x # B018
| ^ B018
6 | x
7 | # Nested expressions isn't relevant
|
B018.ipynb:9:5: B018 Found useless expression. Either assign it to a variable or remove it.
|
7 | # Nested expressions isn't relevant
8 | if True:
9 | x
| ^ B018
10 | # Semicolons shouldn't affect the output
11 | x;
|
B018.ipynb:13:1: B018 Found useless expression. Either assign it to a variable or remove it.
|
11 | x;
12 | # Semicolons with multiple expressions
13 | x; x
| ^ B018
14 | # Comments, newlines and whitespace
15 | x # comment
|

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@ -1,7 +1,9 @@
use std::fmt; use std::fmt;
use std::ops::{Deref, DerefMut}; use std::ops::{Deref, DerefMut};
use ruff_text_size::TextSize; use itertools::Itertools;
use ruff_text_size::{TextRange, TextSize};
use crate::schema::{Cell, SourceValue}; use crate::schema::{Cell, SourceValue};
@ -187,6 +189,17 @@ impl CellOffsets {
pub(crate) fn push(&mut self, offset: TextSize) { pub(crate) fn push(&mut self, offset: TextSize) {
self.0.push(offset); self.0.push(offset);
} }
/// Returns the range of the cell containing the given offset, if any.
pub fn containing_range(&self, offset: TextSize) -> Option<TextRange> {
self.iter().tuple_windows().find_map(|(start, end)| {
if *start <= offset && offset < *end {
Some(TextRange::new(*start, *end))
} else {
None
}
})
}
} }
impl Deref for CellOffsets { impl Deref for CellOffsets {