mirror of
https://github.com/astral-sh/ruff.git
synced 2025-09-28 04:45:01 +00:00
Allow is and is not for direct type comparisons (#7905)
## Summary This PR updates our E721 implementation and semantics to match the updated `pycodestyle` logic, which I think is an improvement. Specifically, we now allow `type(obj) is int` for exact type comparisons, which were previously impossible. So now, we're largely just linting against code like `type(obj) == int`. This change is gated to preview mode. Closes https://github.com/astral-sh/ruff/issues/7904. ## Test Plan Updated the test fixture and ensured parity with latest Flake8.
This commit is contained in:
Charlie Marsh
GitHub
parent
f6d6200aae
commit
df807ff912
5 changed files with 329 additions and 105 deletions
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@ -16,6 +16,7 @@ mod tests {
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use crate::line_width::LineLength;
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use crate::registry::Rule;
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use crate::settings::types::PreviewMode;
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use crate::test::test_path;
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use crate::{assert_messages, settings};
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@ -61,6 +62,24 @@ mod tests {
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Ok(())
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}
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#[test_case(Rule::TypeComparison, Path::new("E721.py"))]
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fn preview_rules(rule_code: Rule, path: &Path) -> Result<()> {
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let snapshot = format!(
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"preview__{}_{}",
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rule_code.noqa_code(),
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path.to_string_lossy()
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);
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let diagnostics = test_path(
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Path::new("pycodestyle").join(path).as_path(),
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&settings::LinterSettings {
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preview: PreviewMode::Enabled,
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..settings::LinterSettings::for_rule(rule_code)
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},
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)?;
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assert_messages!(snapshot, diagnostics);
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Ok(())
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}
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#[test]
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fn w292_4() -> Result<()> {
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let diagnostics = test_path(
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@ -3,26 +3,31 @@ use ruff_diagnostics::{Diagnostic, Violation};
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use ruff_macros::{derive_message_formats, violation};
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use ruff_python_ast::helpers::is_const_none;
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use ruff_python_ast::{self as ast, CmpOp, Expr};
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use ruff_python_semantic::SemanticModel;
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use ruff_text_size::Ranged;
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use crate::checkers::ast::Checker;
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use crate::settings::types::PreviewMode;
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/// ## What it does
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/// Checks for object type comparisons without using `isinstance()`.
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/// Checks for object type comparisons using `==` and other comparison
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/// operators.
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///
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/// ## Why is this bad?
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/// Do not compare types directly.
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/// Unlike a direct type comparison, `isinstance` will also check if an object
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/// is an instance of a class or a subclass thereof.
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///
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/// When checking if an object is a instance of a certain type, keep in mind
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/// that it might be subclassed. For example, `bool` inherits from `int`, and
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/// `Exception` inherits from `BaseException`.
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/// Under [preview mode](https://docs.astral.sh/ruff/preview), this rule also
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/// allows for direct type comparisons using `is` and `is not`, to check for
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/// exact type equality (while still forbidding comparisons using `==` and
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/// `!=`).
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///
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/// ## Example
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/// ```python
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/// if type(obj) is type(1):
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/// if type(obj) == type(1):
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/// pass
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///
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/// if type(obj) is int:
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/// if type(obj) == int:
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/// pass
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/// ```
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///
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@ -32,17 +37,31 @@ use crate::checkers::ast::Checker;
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/// pass
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/// ```
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#[violation]
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pub struct TypeComparison;
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pub struct TypeComparison {
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preview: PreviewMode,
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}
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impl Violation for TypeComparison {
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#[derive_message_formats]
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fn message(&self) -> String {
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format!("Do not compare types, use `isinstance()`")
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match self.preview {
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PreviewMode::Disabled => format!("Do not compare types, use `isinstance()`"),
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PreviewMode::Enabled => format!(
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"Use `is` and `is not` for type comparisons, or `isinstance()` for isinstance checks"
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),
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}
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}
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}
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/// E721
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pub(crate) fn type_comparison(checker: &mut Checker, compare: &ast::ExprCompare) {
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match checker.settings.preview {
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PreviewMode::Disabled => deprecated_type_comparison(checker, compare),
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PreviewMode::Enabled => preview_type_comparison(checker, compare),
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}
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}
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fn deprecated_type_comparison(checker: &mut Checker, compare: &ast::ExprCompare) {
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for ((left, right), op) in std::iter::once(compare.left.as_ref())
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.chain(compare.comparators.iter())
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.tuple_windows()
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@ -82,9 +101,12 @@ pub(crate) fn type_comparison(checker: &mut Checker, compare: &ast::ExprCompare)
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.first()
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.is_some_and(|arg| !arg.is_name_expr() && !is_const_none(arg))
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{
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checker
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.diagnostics
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.push(Diagnostic::new(TypeComparison, compare.range()));
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checker.diagnostics.push(Diagnostic::new(
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TypeComparison {
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preview: PreviewMode::Disabled,
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},
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compare.range(),
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));
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}
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}
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}
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@ -95,9 +117,12 @@ pub(crate) fn type_comparison(checker: &mut Checker, compare: &ast::ExprCompare)
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.resolve_call_path(value.as_ref())
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.is_some_and(|call_path| matches!(call_path.as_slice(), ["types", ..]))
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{
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checker
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.diagnostics
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.push(Diagnostic::new(TypeComparison, compare.range()));
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checker.diagnostics.push(Diagnostic::new(
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TypeComparison {
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preview: PreviewMode::Disabled,
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},
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compare.range(),
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));
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}
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}
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Expr::Name(ast::ExprName { id, .. }) => {
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@ -115,12 +140,66 @@ pub(crate) fn type_comparison(checker: &mut Checker, compare: &ast::ExprCompare)
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| "set"
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) && checker.semantic().is_builtin(id)
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{
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checker
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.diagnostics
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.push(Diagnostic::new(TypeComparison, compare.range()));
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checker.diagnostics.push(Diagnostic::new(
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TypeComparison {
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preview: PreviewMode::Disabled,
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},
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compare.range(),
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));
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}
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}
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_ => {}
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}
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}
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}
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pub(crate) fn preview_type_comparison(checker: &mut Checker, compare: &ast::ExprCompare) {
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for (left, right) in std::iter::once(compare.left.as_ref())
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.chain(compare.comparators.iter())
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.tuple_windows()
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.zip(compare.ops.iter())
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.filter(|(_, op)| matches!(op, CmpOp::Eq | CmpOp::NotEq))
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.map(|((left, right), _)| (left, right))
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{
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if is_type(left, checker.semantic()) || is_type(right, checker.semantic()) {
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checker.diagnostics.push(Diagnostic::new(
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TypeComparison {
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preview: PreviewMode::Enabled,
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},
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compare.range(),
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));
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}
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}
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}
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/// Returns `true` if the [`Expr`] is known to evaluate to a type (e.g., `int`, or `type(1)`).
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fn is_type(expr: &Expr, semantic: &SemanticModel) -> bool {
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match expr {
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Expr::Call(ast::ExprCall {
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func, arguments, ..
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}) => {
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// Ex) `type(obj) == type(1)`
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let Expr::Name(ast::ExprName { id, .. }) = func.as_ref() else {
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return false;
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};
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if !(id == "type" && semantic.is_builtin("type")) {
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return false;
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};
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// Allow comparison for types which are not obvious.
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arguments
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.args
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.first()
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.is_some_and(|arg| !arg.is_name_expr() && !is_const_none(arg))
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}
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Expr::Name(ast::ExprName { id, .. }) => {
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// Ex) `type(obj) == int`
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matches!(
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id.as_str(),
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"int" | "str" | "float" | "bool" | "complex" | "bytes" | "list" | "dict" | "set"
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) && semantic.is_builtin(id)
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}
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_ => false,
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}
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}
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@ -17,7 +17,7 @@ E721.py:5:4: E721 Do not compare types, use `isinstance()`
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5 | if type(res) != type(""):
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| ^^^^^^^^^^^^^^^^^^^^^ E721
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6 | pass
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7 | #: E721
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7 | #: Okay
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E721.py:15:4: E721 Do not compare types, use `isinstance()`
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@ -34,7 +34,7 @@ E721.py:18:8: E721 Do not compare types, use `isinstance()`
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16 | pass
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17 | #: E721
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18 | assert type(res) == type(False)
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18 | assert type(res) == type(False) or type(res) == type(None)
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| ^^^^^^^^^^^^^^^^^^^^^^^^ E721
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19 | #: E721
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20 | assert type(res) == type([])
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@ -42,7 +42,7 @@ E721.py:18:8: E721 Do not compare types, use `isinstance()`
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E721.py:20:8: E721 Do not compare types, use `isinstance()`
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18 | assert type(res) == type(False)
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18 | assert type(res) == type(False) or type(res) == type(None)
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19 | #: E721
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20 | assert type(res) == type([])
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| ^^^^^^^^^^^^^^^^^^^^^ E721
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@ -77,97 +77,84 @@ E721.py:26:8: E721 Do not compare types, use `isinstance()`
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26 | assert type(res) == type((0))
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| ^^^^^^^^^^^^^^^^^^^^^^ E721
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27 | #: E721
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28 | assert type(res) != type((1,))
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28 | assert type(res) != type((1, ))
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E721.py:28:8: E721 Do not compare types, use `isinstance()`
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26 | assert type(res) == type((0))
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27 | #: E721
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28 | assert type(res) != type((1,))
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| ^^^^^^^^^^^^^^^^^^^^^^^ E721
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29 | #: E721
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30 | assert type(res) is type((1,))
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28 | assert type(res) != type((1, ))
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| ^^^^^^^^^^^^^^^^^^^^^^^^ E721
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29 | #: Okay
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30 | assert type(res) is type((1, ))
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E721.py:30:8: E721 Do not compare types, use `isinstance()`
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28 | assert type(res) != type((1,))
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29 | #: E721
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30 | assert type(res) is type((1,))
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| ^^^^^^^^^^^^^^^^^^^^^^^ E721
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31 | #: E721
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32 | assert type(res) is not type((1,))
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28 | assert type(res) != type((1, ))
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29 | #: Okay
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30 | assert type(res) is type((1, ))
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| ^^^^^^^^^^^^^^^^^^^^^^^^ E721
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31 | #: Okay
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32 | assert type(res) is not type((1, ))
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E721.py:32:8: E721 Do not compare types, use `isinstance()`
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30 | assert type(res) is type((1,))
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31 | #: E721
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32 | assert type(res) is not type((1,))
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^ E721
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30 | assert type(res) is type((1, ))
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31 | #: Okay
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32 | assert type(res) is not type((1, ))
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^^^ E721
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33 | #: E211 E721
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34 | assert type(res) == type(
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34 | assert type(res) == type ([2, ])
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E721.py:34:8: E721 Do not compare types, use `isinstance()`
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32 | assert type(res) is not type((1,))
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33 | #: E211 E721
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34 | assert type(res) == type(
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| ________^
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35 | | [
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36 | | 2,
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37 | | ]
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38 | | )
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| |_^ E721
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39 | #: E201 E201 E202 E721
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40 | assert type(res) == type(())
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32 | assert type(res) is not type((1, ))
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33 | #: E211 E721
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34 | assert type(res) == type ([2, ])
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| ^^^^^^^^^^^^^^^^^^^^^^^^^ E721
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35 | #: E201 E201 E202 E721
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36 | assert type(res) == type( ( ) )
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E721.py:40:8: E721 Do not compare types, use `isinstance()`
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E721.py:36:8: E721 Do not compare types, use `isinstance()`
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|
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38 | )
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39 | #: E201 E201 E202 E721
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40 | assert type(res) == type(())
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| ^^^^^^^^^^^^^^^^^^^^^ E721
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41 | #: E201 E202 E721
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42 | assert type(res) == type((0,))
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34 | assert type(res) == type ([2, ])
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35 | #: E201 E201 E202 E721
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36 | assert type(res) == type( ( ) )
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| ^^^^^^^^^^^^^^^^^^^^^^^^ E721
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37 | #: E201 E202 E721
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38 | assert type(res) == type( (0, ) )
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E721.py:42:8: E721 Do not compare types, use `isinstance()`
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E721.py:38:8: E721 Do not compare types, use `isinstance()`
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40 | assert type(res) == type(())
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41 | #: E201 E202 E721
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42 | assert type(res) == type((0,))
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| ^^^^^^^^^^^^^^^^^^^^^^^ E721
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43 |
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44 | #: Okay
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36 | assert type(res) == type( ( ) )
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37 | #: E201 E202 E721
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38 | assert type(res) == type( (0, ) )
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| ^^^^^^^^^^^^^^^^^^^^^^^^^^ E721
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39 | #:
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|
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E721.py:63:8: E721 Do not compare types, use `isinstance()`
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E721.py:96:12: E721 Do not compare types, use `isinstance()`
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|
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62 | #: E721
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63 | assert type(res) is int
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| ^^^^^^^^^^^^^^^^ E721
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|
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E721.py:69:12: E721 Do not compare types, use `isinstance()`
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|
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67 | def asdf(self, value: str | None):
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68 | #: E721
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69 | if type(value) is str:
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94 | def asdf(self, value: str | None):
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95 | #: E721
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96 | if type(value) is str:
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| ^^^^^^^^^^^^^^^^^^ E721
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70 | ...
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97 | ...
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|
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E721.py:79:12: E721 Do not compare types, use `isinstance()`
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|
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77 | def asdf(self, value: str | None):
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78 | #: E721
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79 | if type(value) is str:
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| ^^^^^^^^^^^^^^^^^^ E721
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80 | ...
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|
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E721.py:106:12: E721 Do not compare types, use `isinstance()`
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|
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104 | def asdf(self, value: str | None):
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105 | #: E721
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106 | if type(value) is str:
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| ^^^^^^^^^^^^^^^^^^ E721
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107 | ...
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|
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|
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@ -0,0 +1,112 @@
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---
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source: crates/ruff_linter/src/rules/pycodestyle/mod.rs
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---
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E721.py:2:4: E721 Use `is` and `is not` for type comparisons, or `isinstance()` for isinstance checks
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|
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1 | #: E721
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2 | if type(res) == type(42):
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| ^^^^^^^^^^^^^^^^^^^^^ E721
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3 | pass
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4 | #: E721
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|
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E721.py:5:4: E721 Use `is` and `is not` for type comparisons, or `isinstance()` for isinstance checks
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|
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3 | pass
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4 | #: E721
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5 | if type(res) != type(""):
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| ^^^^^^^^^^^^^^^^^^^^^ E721
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6 | pass
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7 | #: Okay
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|
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E721.py:18:8: E721 Use `is` and `is not` for type comparisons, or `isinstance()` for isinstance checks
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|
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16 | pass
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17 | #: E721
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18 | assert type(res) == type(False) or type(res) == type(None)
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| ^^^^^^^^^^^^^^^^^^^^^^^^ E721
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19 | #: E721
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20 | assert type(res) == type([])
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|
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E721.py:20:8: E721 Use `is` and `is not` for type comparisons, or `isinstance()` for isinstance checks
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|
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18 | assert type(res) == type(False) or type(res) == type(None)
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19 | #: E721
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20 | assert type(res) == type([])
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| ^^^^^^^^^^^^^^^^^^^^^ E721
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21 | #: E721
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22 | assert type(res) == type(())
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|
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E721.py:22:8: E721 Use `is` and `is not` for type comparisons, or `isinstance()` for isinstance checks
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|
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20 | assert type(res) == type([])
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21 | #: E721
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22 | assert type(res) == type(())
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| ^^^^^^^^^^^^^^^^^^^^^ E721
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23 | #: E721
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24 | assert type(res) == type((0,))
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|
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E721.py:24:8: E721 Use `is` and `is not` for type comparisons, or `isinstance()` for isinstance checks
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|
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22 | assert type(res) == type(())
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23 | #: E721
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24 | assert type(res) == type((0,))
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| ^^^^^^^^^^^^^^^^^^^^^^^ E721
|
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25 | #: E721
|
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26 | assert type(res) == type((0))
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|
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|
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E721.py:26:8: E721 Use `is` and `is not` for type comparisons, or `isinstance()` for isinstance checks
|
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|
|
||||
24 | assert type(res) == type((0,))
|
||||
25 | #: E721
|
||||
26 | assert type(res) == type((0))
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^ E721
|
||||
27 | #: E721
|
||||
28 | assert type(res) != type((1, ))
|
||||
|
|
||||
|
||||
E721.py:28:8: E721 Use `is` and `is not` for type comparisons, or `isinstance()` for isinstance checks
|
||||
|
|
||||
26 | assert type(res) == type((0))
|
||||
27 | #: E721
|
||||
28 | assert type(res) != type((1, ))
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^ E721
|
||||
29 | #: Okay
|
||||
30 | assert type(res) is type((1, ))
|
||||
|
|
||||
|
||||
E721.py:34:8: E721 Use `is` and `is not` for type comparisons, or `isinstance()` for isinstance checks
|
||||
|
|
||||
32 | assert type(res) is not type((1, ))
|
||||
33 | #: E211 E721
|
||||
34 | assert type(res) == type ([2, ])
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^ E721
|
||||
35 | #: E201 E201 E202 E721
|
||||
36 | assert type(res) == type( ( ) )
|
||||
|
|
||||
|
||||
E721.py:36:8: E721 Use `is` and `is not` for type comparisons, or `isinstance()` for isinstance checks
|
||||
|
|
||||
34 | assert type(res) == type ([2, ])
|
||||
35 | #: E201 E201 E202 E721
|
||||
36 | assert type(res) == type( ( ) )
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^ E721
|
||||
37 | #: E201 E202 E721
|
||||
38 | assert type(res) == type( (0, ) )
|
||||
|
|
||||
|
||||
E721.py:38:8: E721 Use `is` and `is not` for type comparisons, or `isinstance()` for isinstance checks
|
||||
|
|
||||
36 | assert type(res) == type( ( ) )
|
||||
37 | #: E201 E202 E721
|
||||
38 | assert type(res) == type( (0, ) )
|
||||
| ^^^^^^^^^^^^^^^^^^^^^^^^^^ E721
|
||||
39 | #:
|
||||
|
|
||||
|
||||
|
||||
Loading…
Add table
Add a link
Reference in a new issue