astral-sh/ruff · error

Expected statement to be embedded in a function definition

Error message

Expected statement to be embedded in a function definition

What it means

An anyhow bail! in the PT018 composite-condition fixer: after re-parsing the reconstructed module, the expected wrapping function definition was not found, so the rewritten assert statement cannot be extracted. The fix is abandoned rather than emitting broken code.

Source

Thrown at crates/ruff_linter/src/rules/flake8_pytest_style/rules/assertion.rs:759

    let module_text = if outer_indent.is_empty() {
        Cow::Borrowed(contents)
    } else {
        Cow::Owned(format!(
            "def f():{}{contents}",
            stylist.line_ending().as_str()
        ))
    };

    // Parse the CST.
    let mut tree = match_module(&module_text)?;

    // Extract the assert statement.
    let statements = if outer_indent.is_empty() {
        &mut tree.body
    } else {
        let [Statement::Compound(CompoundStatement::FunctionDef(embedding))] = &mut *tree.body
        else {
            bail!("Expected statement to be embedded in a function definition")
        };

        let indented_block = match_indented_block(&mut embedding.body)?;
        indented_block.indent = Some(outer_indent);

        &mut indented_block.body
    };

    let [Statement::Simple(simple_statement_line)] = statements.as_slice() else {
        bail!("Expected one simple statement")
    };

    let [SmallStatement::Assert(assert_statement)] = simple_statement_line.body.as_slice() else {
        bail!("Expected simple statement to be an assert")
    };

    // Extract the individual conditions.
    let mut conditions: Vec<Expression> = Vec::with_capacity(2);

View on GitHub (pinned to 26f38c119c)

Solutions

1. Verify the module reconstruction logic that embeds the statement in a function
2. Skip the fix when the re-parsed tree does not have the expected shape

When it happens

Trigger: Thrown at crates/ruff_linter/src/rules/flake8_pytest_style/rules/assertion.rs:759 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/6f047dd8afb4e2ec. Report an issue: GitHub.