astral-sh/ruff · error

Expected assert statement to be a composite condition

Error message

Expected assert statement to be a composite condition

What it means

An anyhow bail! in the PT018 composite-condition fixer: the assert statement's test does not decompose into the composite (and/or with not) condition shapes the fixer knows how to split into individual conditions. The fix is aborted rather than producing a wrong rewrite.

Source

Thrown at crates/ruff_linter/src/rules/flake8_pytest_style/rules/assertion.rs:792

    };

    // Extract the individual conditions.
    let mut conditions: Vec<Expression> = Vec::with_capacity(2);
    match &assert_statement.test {
        Expression::UnaryOperation(op) => {
            if matches!(op.operator, libcst_native::UnaryOp::Not { .. }) {
                if let Expression::BooleanOperation(boolean_operation) = &*op.expression {
                    if matches!(boolean_operation.operator, BooleanOp::Or { .. }) {
                        conditions.push(negate(&parenthesize(
                            &boolean_operation.left,
                            &op.expression,
                        )));
                        conditions.push(negate(&parenthesize(
                            &boolean_operation.right,
                            &op.expression,
                        )));
                    } else {
                        bail!("Expected assert statement to be a composite condition");
                    }
                } else {
                    bail!("Expected assert statement to be a composite condition");
                }
            }
        }
        Expression::BooleanOperation(op) => {
            if matches!(op.operator, BooleanOp::And { .. }) {
                conditions.push(parenthesize(&op.left, &assert_statement.test));
                conditions.push(parenthesize(&op.right, &assert_statement.test));
            } else {
                bail!("Expected assert statement to be a composite condition");
            }
        }
        _ => bail!("Expected assert statement to be a composite condition"),
    }

    // For each condition, create an `assert condition` statement.

View on GitHub (pinned to 26f38c119c)

Solutions

1. Extend the condition extraction to cover the encountered expression shape
2. Restrict the rule to condition shapes the fixer can decompose

When it happens

Trigger: Thrown at crates/ruff_linter/src/rules/flake8_pytest_style/rules/assertion.rs:792 when the library encounters an invalid state.

Common situations: See trigger scenarios.

AI-assisted analysis of astral-sh/ruff@26f38c119c (2026-09-05). Data as JSON: /api/errors/f0563e0f08a4ade5. Report an issue: GitHub.