rust_browser/tests/js_modules.rs

//! Integration tests for ES module support (Story 3.4).
//!
//! Tests exercise module parsing, inline module execution, module scope
//! isolation, and module deferred execution timing through the WebApiFacade.
//! Additional tests exercise actual module execution via BrowserRuntime.

use browser_runtime::BrowserRuntime;
use dom::Document;
#[allow(clippy::single_component_path_imports)]
use net;
use shared::NodeId;
use web_api::WebApiFacade;

// ---------------------------------------------------------------------------
// Test helper
// ---------------------------------------------------------------------------

fn setup() -> (WebApiFacade, NodeId) {
    let mut facade = WebApiFacade::new_for_testing();
    let doc = facade.document_mut();
    let root = doc.root().unwrap();
    let html = doc.create_element("html");
    doc.append_child(root, html);
    let body = doc.create_element("body");
    doc.append_child(html, body);
    let div = doc.create_element("div");
    doc.set_attribute(div, "id", "out");
    doc.append_child(body, div);
    let text = doc.create_text("initial");
    doc.append_child(div, text);
    facade.bootstrap().unwrap();
    (facade, div)
}

// ---------------------------------------------------------------------------
// 1. Inline module execution — basic const/var in module scope
// ---------------------------------------------------------------------------

#[test]
fn inline_module_executes_basic_code() {
    let (mut facade, div) = setup();
    let network = net::NetworkStack::new();

    // Execute a module that sets textContent via DOM — modules can access
    // globals through the scope chain.
    facade
        .execute_module(
            "file:///inline-test.js",
            r#"
        var el = document.getElementById("out");
        el.textContent = "module_ran";
        "#,
            &network,
        )
        .unwrap();

    assert_eq!(facade.document().text_content(div), "module_ran");
}

// ---------------------------------------------------------------------------
// 2. Module is implicitly strict mode
// ---------------------------------------------------------------------------

#[test]
fn module_parse_is_strict_mode() {
    // Parsing as module enables strict mode — verify by parsing
    let parser = js_parser::JsParser::new();
    let prog = parser.parse_module("var x = 1;").unwrap();
    assert!(prog.strict, "module should be in strict mode");
    assert!(prog.is_module, "module should have is_module flag");
}

// ---------------------------------------------------------------------------
// 3. Import/export declarations parse without error in module mode
// ---------------------------------------------------------------------------

#[test]
fn module_import_export_parses() {
    let parser = js_parser::JsParser::new();
    let prog = parser
        .parse_module("export const x = 42; export default x;")
        .unwrap();
    assert_eq!(prog.body.len(), 2);
}

// ---------------------------------------------------------------------------
// 4. Export const declaration executes in module mode
// ---------------------------------------------------------------------------

#[test]
fn module_export_const_executes() {
    let (mut facade, div) = setup();
    let network = net::NetworkStack::new();

    // Export declarations should compile and execute (inner declaration runs)
    facade
        .execute_module(
            "file:///test-export.js",
            r#"
        export const x = 42;
        var el = document.getElementById("out");
        el.textContent = "exported";
        "#,
            &network,
        )
        .unwrap();

    assert_eq!(facade.document().text_content(div), "exported");
}

// ---------------------------------------------------------------------------
// 5. Dynamic import() parses in both module and classic scripts
// ---------------------------------------------------------------------------

#[test]
fn dynamic_import_parses_in_classic_script() {
    let parser = js_parser::JsParser::new();
    let prog = parser.parse("var p = import('./foo.js');").unwrap();
    assert_eq!(prog.body.len(), 1);
}

#[test]
fn dynamic_import_parses_in_module() {
    let parser = js_parser::JsParser::new();
    let prog = parser.parse_module("var p = import('./foo.js');").unwrap();
    assert_eq!(prog.body.len(), 1);
}

// ---------------------------------------------------------------------------
// 6. Import/export in non-module context produces error
// ---------------------------------------------------------------------------

#[test]
fn import_in_classic_script_is_error() {
    let parser = js_parser::JsParser::new();
    let err = parser.parse("import { foo } from './bar.js';").unwrap_err();
    assert!(
        err.message.contains("import"),
        "error should mention import: {}",
        err.message
    );
}

#[test]
fn export_in_classic_script_is_error() {
    let parser = js_parser::JsParser::new();
    let err = parser.parse("export const x = 1;").unwrap_err();
    assert!(
        err.message.contains("export"),
        "error should mention export: {}",
        err.message
    );
}

// ---------------------------------------------------------------------------
// 7. All import syntax variations parse correctly
// ---------------------------------------------------------------------------

#[test]
fn all_import_forms_parse() {
    let parser = js_parser::JsParser::new();
    let sources = vec![
        "import { a } from './m.js';",
        "import { a as b } from './m.js';",
        "import def from './m.js';",
        "import * as ns from './m.js';",
        "import def, { a } from './m.js';",
        "import def, * as ns from './m.js';",
        "import './m.js';",
    ];
    for src in sources {
        assert!(parser.parse_module(src).is_ok(), "should parse: {}", src);
    }
}

// ---------------------------------------------------------------------------
// 8. All export syntax variations parse correctly
// ---------------------------------------------------------------------------

#[test]
fn all_export_forms_parse() {
    let parser = js_parser::JsParser::new();
    let sources = vec![
        "export default 42;",
        "export default function foo() {}",
        "export default class Foo {}",
        "export const x = 1;",
        "export let y = 2;",
        "export var z = 3;",
        "export function fn1() {}",
        "export class C1 {}",
        "var a = 1; export { a };",
        "var a = 1; export { a as b };",
        "export { a } from './m.js';",
        "export * from './m.js';",
        "export * as ns from './m.js';",
    ];
    for src in sources {
        assert!(parser.parse_module(src).is_ok(), "should parse: {}", src);
    }
}

// ---------------------------------------------------------------------------
// 9. `from` and `as` work as variable names (not keywords)
// ---------------------------------------------------------------------------

#[test]
fn from_and_as_are_valid_identifiers() {
    let parser = js_parser::JsParser::new();
    // In classic scripts
    assert!(parser.parse("var from = 1; var as = 2;").is_ok());
    // In module mode too
    assert!(parser.parse_module("var from = 1; var as = 2;").is_ok());
}

// ---------------------------------------------------------------------------
// Helper: set up a BrowserRuntime with a document ready for module execution.
// ---------------------------------------------------------------------------

fn setup_runtime_with_document() -> BrowserRuntime {
    let mut rt = BrowserRuntime::new();
    rt.prepare_for_navigation().unwrap();

    let mut doc = Document::new();
    let root = doc.root().unwrap();
    let html = doc.create_element("html");
    doc.append_child(root, html);
    let body = doc.create_element("body");
    doc.append_child(html, body);

    rt.set_document(doc);
    rt
}

// ---------------------------------------------------------------------------
// 10. Module execution via execute_module (not execute_script)
// ---------------------------------------------------------------------------

#[test]
fn module_export_const_runs_via_module_path() {
    let mut rt = setup_runtime_with_document();

    // Execute a simple module with an export declaration.
    // This validates the full module execution pipeline: parse as module,
    // compile, and execute via execute_module().
    let result = rt.execute_module("file:///test-module.js", "export const x = 42;");
    assert!(
        result.is_ok(),
        "execute_module should succeed for a simple export const: {result:?}"
    );
}

// ---------------------------------------------------------------------------
// 11. Module execution with DOM mutation
// ---------------------------------------------------------------------------

#[test]
fn module_with_dom_mutation() {
    let mut rt = BrowserRuntime::new();
    rt.prepare_for_navigation().unwrap();

    // Build a document with a target div whose textContent we will mutate.
    let mut doc = Document::new();
    let root = doc.root().unwrap();
    let html = doc.create_element("html");
    doc.append_child(root, html);
    let body = doc.create_element("body");
    doc.append_child(html, body);
    let div = doc.create_element("div");
    doc.set_attribute(div, "id", "target");
    doc.append_child(body, div);
    let text = doc.create_text("original");
    doc.append_child(div, text);

    rt.set_document(doc);

    // Execute a module that mutates the DOM via document.getElementById.
    let result = rt.execute_module(
        "file:///dom-module.js",
        r#"
        var el = document.getElementById('target');
        if (el) { el.textContent = 'module-executed'; }
        "#,
    );
    assert!(
        result.is_ok(),
        "module with DOM mutation should execute without error: {result:?}"
    );

    // Verify the DOM was mutated by the module.
    let doc = rt.take_document();
    assert_eq!(
        doc.text_content(div),
        "module-executed",
        "module should have set textContent on the target div"
    );
}

// ---------------------------------------------------------------------------
// 12. Module strict mode is enforced at execution time
// ---------------------------------------------------------------------------

#[test]
fn module_strict_mode_enforced() {
    let mut rt = setup_runtime_with_document();

    // In strict mode, assigning to an undeclared variable is an error.
    // Modules are always strict, so this should fail.
    let result = rt.execute_module("file:///strict-module.js", "x = 42;");
    assert!(
        result.is_err(),
        "module should enforce strict mode: assigning to undeclared variable must be an error"
    );
}

// ---------------------------------------------------------------------------
// 13. Dynamic import() returns a value (currently a placeholder)
// ---------------------------------------------------------------------------

#[test]
fn dynamic_import_executes_without_crash() {
    let mut rt = setup_runtime_with_document();

    // Dynamic import() is compiled and executed. Currently the opcode handler
    // returns undefined (full Promise-based resolution is deferred).
    // This test verifies it doesn't crash or produce a parse error.
    let result = rt.execute_module(
        "file:///dynamic-import.js",
        "var result = import('./other.js'); export const ok = true;",
    );
    assert!(
        result.is_ok(),
        "dynamic import() should not crash: {result:?}"
    );
}

// ---------------------------------------------------------------------------
// 14. Bare module specifier is rejected
// ---------------------------------------------------------------------------

#[test]
fn bare_specifier_rejected() {
    let mut rt = setup_runtime_with_document();

    // Bare specifiers like 'lodash' should be rejected (no import map support).
    let result = rt.execute_module("file:///main.js", "import 'lodash';");
    assert!(result.is_err(), "bare specifier should be rejected");
    let err_msg = format!("{:?}", result.unwrap_err());
    assert!(
        err_msg.contains("bare module specifier"),
        "error should mention bare specifier: {err_msg}"
    );
}

// ---------------------------------------------------------------------------
// 15. Deferred script and module interleaving in document order
// ---------------------------------------------------------------------------

#[test]
fn deferred_and_module_interleaving_order() {
    use app_browser::pipeline::{DeferredItem, ScheduledScripts};

    // Build ScheduledScripts with interleaved defer + module items.
    // Expected execution order: defer1 → module1 → defer2
    // Ordering correctness is validated by unit tests in script_tests.rs;
    // this integration test verifies the full pipeline executes without error.
    let mut scheduled = ScheduledScripts::default();
    scheduled.deferred_order.push(DeferredItem::Script(
        "var order = []; order.push('defer1');".to_string(),
        "<defer1>".to_string(),
    ));
    scheduled.deferred_order.push(DeferredItem::Module(
        "order.push('module1'); export const ok = true;".to_string(),
        "<module1>".to_string(),
        Some("file:///module1.js".to_string()),
    ));
    scheduled.deferred_order.push(DeferredItem::Script(
        "order.push('defer2');".to_string(),
        "<defer2>".to_string(),
    ));

    let mut rt = setup_runtime_with_document();

    // Execute each item in deferred_order — mirrors event_handler.rs logic
    for item in &scheduled.deferred_order {
        match item {
            DeferredItem::Script(js_text, _label) => {
                rt.execute_script(js_text).unwrap();
            }
            DeferredItem::Module(js_text, _label, module_url) => {
                let url = module_url.as_deref().unwrap_or("inline-module");
                rt.execute_module(url, js_text).unwrap();
            }
        }
    }
}

// ---------------------------------------------------------------------------
// 16. ES Module live bindings (H7)
// ---------------------------------------------------------------------------

// Live bindings are thoroughly tested in crates/js_vm/src/interpreter/tests/module_tests.rs
// (module_live_binding_let_mutation, module_live_binding_multiple_mutations, etc.)
// No duplicate integration test needed — the VM tests already exercise run_module().