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refactor(linter/expect-expect): use visitor pattern to detect expect calls #12906

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Aug 8, 2025
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refactor(linter/expect-expect): use visitor pattern to detect expect calls #12906

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227 changes: 117 additions & 110 deletions crates/oxc_linter/src/rules/jest/expect_expect.rs
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Original file line number Diff line number Diff line change
@@ -1,13 +1,16 @@
use cow_utils::CowUtils;
use lazy_regex::Regex;
use rustc_hash::FxHashSet;

use oxc_ast::{
AstKind,
ast::{CallExpression, Expression, Statement},
ast::{CallExpression, Expression, FormalParameter, Function, Statement},
};
use oxc_ast_visit::{Visit, walk};
use oxc_diagnostics::OxcDiagnostic;
use oxc_macros::declare_oxc_lint;
use oxc_span::{CompactStr, GetSpan, Span};
use rustc_hash::FxHashSet;
use oxc_syntax::scope::ScopeFlags;

use crate::{
ast_util::get_declaration_of_variable,
Expand Down Expand Up @@ -162,141 +165,145 @@ fn run<'a>(
}
}

// Record visited nodes to avoid infinite loop.
let mut visited: FxHashSet<Span> = FxHashSet::default();

let has_assert_function = if ctx.frameworks().is_vitest() {
check_arguments(call_expr, &rule.assert_function_names_vitest, &mut visited, ctx)
let assert_function_names = if ctx.frameworks().is_vitest() {
&rule.assert_function_names_vitest
} else {
check_arguments(call_expr, &rule.assert_function_names_jest, &mut visited, ctx)
&rule.assert_function_names_jest
};

if !has_assert_function {
let mut visitor = AssertionVisitor::new(ctx, assert_function_names);

// Visit each argument of the test call
for argument in &call_expr.arguments {
if let Some(expr) = argument.as_expression() {
visitor.check_expression(expr);
if visitor.found_assertion {
return;
}
}
}

if !visitor.found_assertion {
ctx.diagnostic(expect_expect_diagnostic(call_expr.callee.span()));
}
}
}
}

fn check_arguments<'a>(
call_expr: &'a CallExpression<'a>,
assert_function_names: &[CompactStr],
visited: &mut FxHashSet<Span>,
ctx: &LintContext<'a>,
) -> bool {
for argument in &call_expr.arguments {
if let Some(expr) = argument.as_expression() {
if check_assert_function_used(expr, assert_function_names, visited, ctx) {
return true;
}
}
}
false
struct AssertionVisitor<'a, 'b> {
ctx: &'b LintContext<'a>,
assert_function_names: &'b [CompactStr],
visited: FxHashSet<Span>,
found_assertion: bool,
}

fn check_assert_function_used<'a>(
expr: &'a Expression<'a>,
assert_function_names: &[CompactStr],
visited: &mut FxHashSet<Span>,
ctx: &LintContext<'a>,
) -> bool {
// If we have visited this node before and didn't find any assert function, we can return
// `false` to avoid infinite loop.
//
// ```javascript
// test("should fail", () => {
// function foo() {
// if (condition) {
// foo()
// }
// }
// foo()
// })
// ```
if !visited.insert(expr.span()) {
return false;
impl<'a, 'b> AssertionVisitor<'a, 'b> {
fn new(ctx: &'b LintContext<'a>, assert_function_names: &'b [CompactStr]) -> Self {
Self { ctx, assert_function_names, visited: FxHashSet::default(), found_assertion: false }
}

match expr {
Expression::FunctionExpression(fn_expr) => {
let body = &fn_expr.body;
if let Some(body) = body {
return check_statements(&body.statements, assert_function_names, visited, ctx);
}
}
Expression::ArrowFunctionExpression(arrow_expr) => {
let body = &arrow_expr.body;
return check_statements(&body.statements, assert_function_names, visited, ctx);
fn check_expression(&mut self, expr: &Expression<'a>) {
// Avoid infinite loops by tracking visited expressions
if !self.visited.insert(expr.span()) {
return;
}
Expression::CallExpression(call_expr) => {
let name = get_node_name(&call_expr.callee);
if matches_assert_function_name(&name, assert_function_names) {
return true;
}

// If CallExpression is not an assert function, we need to check its arguments, it may trigger
// another assert function.
// ```javascript
// it('should pass', () => somePromise().then(() => expect(true).toBeDefined()))
// ```
let has_assert_function =
check_arguments(call_expr, assert_function_names, visited, ctx);

return has_assert_function;
}
Expression::Identifier(ident) => {
let Some(node) = get_declaration_of_variable(ident, ctx) else {
return false;
};
let AstKind::Function(function) = node.kind() else {
return false;
};
let Some(body) = &function.body else {
return false;
};
return check_statements(&body.statements, assert_function_names, visited, ctx);
}
Expression::AwaitExpression(expr) => {
return check_assert_function_used(&expr.argument, assert_function_names, visited, ctx);
}
Expression::ArrayExpression(array_expr) => {
for element in &array_expr.elements {
if let Some(element_expr) = element.as_expression() {
if check_assert_function_used(element_expr, assert_function_names, visited, ctx)
{
return true;
match expr {
Expression::FunctionExpression(fn_expr) => {
if let Some(body) = &fn_expr.body {
self.visit_function_body(body);
}
}
Expression::ArrowFunctionExpression(arrow_expr) => {
self.visit_function_body(&arrow_expr.body);
}
Expression::CallExpression(call_expr) => {
self.visit_call_expression(call_expr);
}
Expression::Identifier(ident) => {
self.check_identifier(ident);
}
Expression::AwaitExpression(expr) => {
self.check_expression(&expr.argument);
}
Expression::ArrayExpression(array_expr) => {
for element in &array_expr.elements {
if let Some(element_expr) = element.as_expression() {
self.check_expression(element_expr);
if self.found_assertion {
return;
}
}
}
}
_ => {}
}
_ => {}
}

false
fn check_identifier(&mut self, ident: &oxc_ast::ast::IdentifierReference<'a>) {
let Some(node) = get_declaration_of_variable(ident, self.ctx) else {
return;
};
let AstKind::Function(function) = node.kind() else {
return;
};
if let Some(body) = &function.body {
self.visit_function_body(body);
}
}
}

fn check_statements<'a>(
statements: &'a oxc_allocator::Vec<Statement<'a>>,
assert_function_names: &[CompactStr],
visited: &mut FxHashSet<Span>,
ctx: &LintContext<'a>,
) -> bool {
statements.iter().any(|statement| match statement {
Statement::ExpressionStatement(expr_stmt) => {
check_assert_function_used(&expr_stmt.expression, assert_function_names, visited, ctx)
impl<'a> Visit<'a> for AssertionVisitor<'a, '_> {
fn visit_call_expression(&mut self, call_expr: &CallExpression<'a>) {
let name = get_node_name(&call_expr.callee);
if matches_assert_function_name(&name, self.assert_function_names) {
self.found_assertion = true;
return;
}
Statement::BlockStatement(block_stmt) => {
check_statements(&block_stmt.body, assert_function_names, visited, ctx)

for argument in &call_expr.arguments {
if let Some(expr) = argument.as_expression() {
self.check_expression(expr);
if self.found_assertion {
return;
}
}
}
Statement::IfStatement(if_stmt) => {
if let Statement::BlockStatement(block_stmt) = &if_stmt.consequent {
check_statements(&block_stmt.body, assert_function_names, visited, ctx)
} else {
false

walk::walk_call_expression(self, call_expr);
}

fn visit_expression_statement(&mut self, stmt: &oxc_ast::ast::ExpressionStatement<'a>) {
self.check_expression(&stmt.expression);
if !self.found_assertion {
walk::walk_expression_statement(self, stmt);
}
}

fn visit_block_statement(&mut self, block: &oxc_ast::ast::BlockStatement<'a>) {
for stmt in &block.body {
self.visit_statement(stmt);
if self.found_assertion {
return;
}
}
_ => false,
})
}

fn visit_if_statement(&mut self, if_stmt: &oxc_ast::ast::IfStatement<'a>) {
if let Statement::BlockStatement(block_stmt) = &if_stmt.consequent {
self.visit_block_statement(block_stmt);
}
if self.found_assertion {
return;
}
if let Some(alternate) = &if_stmt.alternate {
self.visit_statement(alternate);
}
}

fn visit_function(&mut self, _func: &Function<'a>, _flags: ScopeFlags) {}

fn visit_formal_parameter(&mut self, _param: &FormalParameter<'a>) {}
}

/// Checks if node names returned by getNodeName matches any of the given star patterns
Expand Down
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