alef_e2e/codegen/

dart.rs

//! Dart e2e test generator using package:test and package:http.
//!
//! Generates `e2e/dart/test/<category>_test.dart` files from JSON fixtures.
//! HTTP fixtures hit the mock server at `MOCK_SERVER_URL/fixtures/<id>`.
//! Non-HTTP fixtures without a dart-specific call override emit a skip stub.

use crate::config::E2eConfig;
use crate::escape::sanitize_filename;
use crate::fixture::{Fixture, FixtureGroup, HttpFixture, ValidationErrorExpectation};
use alef_core::backend::GeneratedFile;
use alef_core::config::ResolvedCrateConfig;
use alef_core::hash::{self, CommentStyle};
use alef_core::template_versions::pub_dev;
use anyhow::Result;
use std::cell::Cell;
use std::fmt::Write as FmtWrite;
use std::path::PathBuf;

use super::E2eCodegen;
use super::client;

/// Dart e2e code generator.
pub struct DartE2eCodegen;

impl E2eCodegen for DartE2eCodegen {
    fn generate(
        &self,
        groups: &[FixtureGroup],
        e2e_config: &E2eConfig,
        config: &ResolvedCrateConfig,
    ) -> Result<Vec<GeneratedFile>> {
        let lang = self.language_name();
        let output_base = PathBuf::from(e2e_config.effective_output()).join(lang);

        let mut files = Vec::new();

        // Resolve package config.
        let dart_pkg = e2e_config.resolve_package("dart");
        let pkg_name = dart_pkg
            .as_ref()
            .and_then(|p| p.name.as_ref())
            .cloned()
            .unwrap_or_else(|| config.dart_pubspec_name());
        let pkg_path = dart_pkg
            .as_ref()
            .and_then(|p| p.path.as_ref())
            .cloned()
            .unwrap_or_else(|| "../../packages/dart".to_string());
        let pkg_version = dart_pkg
            .as_ref()
            .and_then(|p| p.version.as_ref())
            .cloned()
            .or_else(|| config.resolved_version())
            .unwrap_or_else(|| "0.1.0".to_string());

        // Generate pubspec.yaml with http dependency for HTTP client tests.
        files.push(GeneratedFile {
            path: output_base.join("pubspec.yaml"),
            content: render_pubspec(&pkg_name, &pkg_path, &pkg_version, e2e_config.dep_mode),
            generated_header: false,
        });

        // Generate dart_test.yaml to limit parallelism — the mock server uses keep-alive
        // connections and gets overwhelmed when test files run in parallel.
        files.push(GeneratedFile {
            path: output_base.join("dart_test.yaml"),
            content: concat!(
                "# Generated by alef — DO NOT EDIT.\n",
                "# Run test files sequentially to avoid overwhelming the mock server with\n",
                "# concurrent keep-alive connections.\n",
                "concurrency: 1\n",
            )
            .to_string(),
            generated_header: false,
        });

        let test_base = output_base.join("test");

        // One test file per fixture group.
        for group in groups {
            let active: Vec<&Fixture> = group
                .fixtures
                .iter()
                .filter(|f| super::should_include_fixture(f, lang, e2e_config))
                .collect();

            if active.is_empty() {
                continue;
            }

            let filename = format!("{}_test.dart", sanitize_filename(&group.category));
            let content = render_test_file(&group.category, &active, e2e_config, lang);
            files.push(GeneratedFile {
                path: test_base.join(filename),
                content,
                generated_header: true,
            });
        }

        Ok(files)
    }

    fn language_name(&self) -> &'static str {
        "dart"
    }
}

// ---------------------------------------------------------------------------
// Rendering
// ---------------------------------------------------------------------------

fn render_pubspec(
    pkg_name: &str,
    pkg_path: &str,
    pkg_version: &str,
    dep_mode: crate::config::DependencyMode,
) -> String {
    let test_ver = pub_dev::TEST_PACKAGE;
    let http_ver = pub_dev::HTTP_PACKAGE;

    let dep_block = match dep_mode {
        crate::config::DependencyMode::Registry => {
            format!("  {pkg_name}: ^{pkg_version}")
        }
        crate::config::DependencyMode::Local => {
            format!("  {pkg_name}:\n    path: {pkg_path}")
        }
    };

    format!(
        r#"name: e2e_dart
version: 0.1.0
publish_to: none

environment:
  sdk: ">=3.0.0 <4.0.0"

dependencies:
{dep_block}

dev_dependencies:
  test: {test_ver}
  http: {http_ver}
"#
    )
}

fn render_test_file(category: &str, fixtures: &[&Fixture], e2e_config: &E2eConfig, lang: &str) -> String {
    let mut out = String::new();
    out.push_str(&hash::header(CommentStyle::DoubleSlash));

    // Check if any fixture needs the http package (HTTP server tests).
    let has_http_fixtures = fixtures.iter().any(|f| f.is_http_test());

    let _ = writeln!(out, "import 'package:test/test.dart';");
    let _ = writeln!(out, "import 'dart:io';");
    if has_http_fixtures {
        let _ = writeln!(out, "import 'dart:async';");
        let _ = writeln!(out, "import 'dart:convert';");
    }
    let _ = writeln!(out);

    // Emit file-level HTTP client and serialization mutex.
    //
    // The shared HttpClient reuses keep-alive connections to minimize TCP overhead.
    // The mutex (_lock) ensures requests are serialized within the file so the
    // connection pool is not exercised concurrently by dart:test's async runner.
    //
    // _withRetry wraps the entire request closure with one automatic retry on
    // transient connection errors (keep-alive connections can be silently closed
    // by the server just as the client tries to reuse them).
    if has_http_fixtures {
        let _ = writeln!(out, "HttpClient _httpClient = HttpClient()..maxConnectionsPerHost = 1;");
        let _ = writeln!(out);
        let _ = writeln!(out, "var _lock = Future<void>.value();");
        let _ = writeln!(out);
        let _ = writeln!(out, "Future<T> _serialized<T>(Future<T> Function() fn) async {{");
        let _ = writeln!(out, "  final current = _lock;");
        let _ = writeln!(out, "  final next = Completer<void>();");
        let _ = writeln!(out, "  _lock = next.future;");
        let _ = writeln!(out, "  try {{");
        let _ = writeln!(out, "    await current;");
        let _ = writeln!(out, "    return await fn();");
        let _ = writeln!(out, "  }} finally {{");
        let _ = writeln!(out, "    next.complete();");
        let _ = writeln!(out, "  }}");
        let _ = writeln!(out, "}}");
        let _ = writeln!(out);
        // The `fn` here should be the full request closure — on socket failure we
        // recreate the HttpClient (drops old pooled connections) and retry once.
        let _ = writeln!(out, "Future<T> _withRetry<T>(Future<T> Function() fn) async {{");
        let _ = writeln!(out, "  try {{");
        let _ = writeln!(out, "    return await fn();");
        let _ = writeln!(out, "  }} on SocketException {{");
        let _ = writeln!(out, "    _httpClient.close(force: true);");
        let _ = writeln!(out, "    _httpClient = HttpClient()..maxConnectionsPerHost = 1;");
        let _ = writeln!(out, "    return fn();");
        let _ = writeln!(out, "  }} on HttpException {{");
        let _ = writeln!(out, "    _httpClient.close(force: true);");
        let _ = writeln!(out, "    _httpClient = HttpClient()..maxConnectionsPerHost = 1;");
        let _ = writeln!(out, "    return fn();");
        let _ = writeln!(out, "  }}");
        let _ = writeln!(out, "}}");
        let _ = writeln!(out);
    }

    let _ = writeln!(out, "// E2e tests for category: {category}");
    let _ = writeln!(out, "void main() {{");

    // Close the shared client after all tests in this file complete.
    if has_http_fixtures {
        let _ = writeln!(out, "  tearDownAll(() => _httpClient.close());");
        let _ = writeln!(out);
    }

    for fixture in fixtures {
        render_test_case(&mut out, fixture, e2e_config, lang);
    }

    let _ = writeln!(out, "}}");
    out
}

fn render_test_case(out: &mut String, fixture: &Fixture, e2e_config: &E2eConfig, lang: &str) {
    // HTTP fixtures: hit the mock server.
    if let Some(http) = &fixture.http {
        render_http_test_case(out, fixture, http);
        return;
    }

    // Non-HTTP fixtures: check if there is a dart-specific call override.
    let call_config = e2e_config.resolve_call(fixture.call.as_deref());
    let call_overrides = call_config.overrides.get(lang);

    if call_overrides.is_none() {
        // No dart-specific call override — emit a skip stub.
        render_skip_stub(out, fixture);
        return;
    }

    // Has a dart call override — render a call-based test.
    let function_name = call_overrides
        .and_then(|o| o.function.as_ref())
        .cloned()
        .unwrap_or_else(|| call_config.function.clone());
    let result_var = &call_config.result_var;
    let description = escape_dart(&fixture.description);
    let is_async = call_config.r#async;

    if is_async {
        let _ = writeln!(out, "  test('{description}', () async {{");
    } else {
        let _ = writeln!(out, "  test('{description}', () {{");
    }

    if is_async {
        let _ = writeln!(out, "    final {result_var} = await {function_name}();");
    } else {
        let _ = writeln!(out, "    final {result_var} = {function_name}();");
    }

    let _ = writeln!(out, "  }});");
    let _ = writeln!(out);
}

// ---------------------------------------------------------------------------
// HTTP server test rendering — DartTestClientRenderer impl + thin driver wrapper
// ---------------------------------------------------------------------------

/// Renderer that emits `package:test` `test(...)` blocks using `dart:io HttpClient`
/// against the mock server (`Platform.environment['MOCK_SERVER_URL']`).
///
/// Skipped tests are emitted as self-contained stubs (complete test block with
/// `markTestSkipped`) entirely inside `render_test_open`. `render_test_close` uses
/// `in_skip` to emit the right closing token: nothing extra for skip stubs (already
/// closed) vs. `})));` for regular tests.
///
/// `is_redirect` must be set to `true` before invoking the shared driver for 3xx
/// fixtures so that `render_call` can inject `ioReq.followRedirects = false` after
/// the `openUrl` call.
struct DartTestClientRenderer {
    /// Set to `true` when `render_test_open` is called with a skip reason so that
    /// `render_test_close` can match the opening shape.
    in_skip: Cell<bool>,
    /// Pre-set to `true` by the thin wrapper when the fixture expects a 3xx response.
    /// `render_call` injects `ioReq.followRedirects = false` when this is `true`.
    is_redirect: Cell<bool>,
}

impl DartTestClientRenderer {
    fn new(is_redirect: bool) -> Self {
        Self {
            in_skip: Cell::new(false),
            is_redirect: Cell::new(is_redirect),
        }
    }
}

impl client::TestClientRenderer for DartTestClientRenderer {
    fn language_name(&self) -> &'static str {
        "dart"
    }

    /// Emit the test opening.
    ///
    /// For skipped fixtures: emit the entire self-contained stub (open + body +
    /// close + blank line) and set `in_skip = true` so `render_test_close` is a
    /// no-op.
    ///
    /// For active fixtures: emit `test('desc', () => _serialized(() => _withRetry(() async {`
    /// leaving the block open for the assertion primitives.
    fn render_test_open(&self, out: &mut String, _fn_name: &str, description: &str, skip_reason: Option<&str>) {
        let escaped_desc = escape_dart(description);
        if let Some(reason) = skip_reason {
            let escaped_reason = escape_dart(reason);
            let _ = writeln!(out, "  test('{escaped_desc}', () {{");
            let _ = writeln!(out, "    markTestSkipped('{escaped_reason}');");
            let _ = writeln!(out, "  }});");
            let _ = writeln!(out);
            self.in_skip.set(true);
        } else {
            let _ = writeln!(
                out,
                "  test('{escaped_desc}', () => _serialized(() => _withRetry(() async {{"
            );
            self.in_skip.set(false);
        }
    }

    /// Emit the test closing token.
    ///
    /// No-op for skip stubs (the stub was fully closed in `render_test_open`).
    /// Emits `})));` followed by a blank line for regular tests.
    fn render_test_close(&self, out: &mut String) {
        if self.in_skip.get() {
            // Stub was already closed in render_test_open.
            return;
        }
        let _ = writeln!(out, "  }})));");
        let _ = writeln!(out);
    }

    /// Emit the full `dart:io HttpClient` request scaffolding.
    ///
    /// Emits:
    /// - URL construction from `MOCK_SERVER_URL`.
    /// - `_httpClient.openUrl(method, uri)`.
    /// - `followRedirects = false` when `is_redirect` is pre-set on the renderer.
    /// - Content-Type header, request headers, cookies, optional body bytes.
    /// - `ioReq.close()` → `ioResp`.
    /// - Response-body drain into `bodyStr` (skipped for redirect responses).
    fn render_call(&self, out: &mut String, ctx: &client::CallCtx<'_>) {
        // dart:io restricted headers (handled automatically by the HTTP stack).
        const DART_RESTRICTED_HEADERS: &[&str] = &["content-length", "host", "transfer-encoding"];

        let method = ctx.method.to_uppercase();
        let escaped_method = escape_dart(&method);

        // Fixture path is `/fixtures/<id>` — extract the id portion for URL construction.
        let fixture_path = escape_dart(ctx.path);

        // Determine effective content-type.
        let has_explicit_content_type = ctx.headers.keys().any(|k| k.to_lowercase() == "content-type");
        let effective_content_type = if has_explicit_content_type {
            ctx.headers
                .iter()
                .find(|(k, _)| k.to_lowercase() == "content-type")
                .map(|(_, v)| v.as_str())
                .unwrap_or("application/json")
        } else if ctx.body.is_some() {
            ctx.content_type.unwrap_or("application/json")
        } else {
            ""
        };

        let _ = writeln!(
            out,
            "    final baseUrl = Platform.environment['MOCK_SERVER_URL'] ?? 'http://localhost:8080';"
        );
        let _ = writeln!(out, "    final uri = Uri.parse('$baseUrl{fixture_path}');");
        let _ = writeln!(
            out,
            "    final ioReq = await _httpClient.openUrl('{escaped_method}', uri);"
        );

        // Disable automatic redirect following for 3xx fixtures so the test can
        // assert on the redirect status code itself.
        if self.is_redirect.get() {
            let _ = writeln!(out, "    ioReq.followRedirects = false;");
        }

        // Set content-type header.
        if !effective_content_type.is_empty() {
            let escaped_ct = escape_dart(effective_content_type);
            let _ = writeln!(out, "    ioReq.headers.set('content-type', '{escaped_ct}');");
        }

        // Set request headers (skip dart:io restricted headers and content-type, already handled).
        let mut header_pairs: Vec<(&String, &String)> = ctx.headers.iter().collect();
        header_pairs.sort_by_key(|(k, _)| k.as_str());
        for (name, value) in &header_pairs {
            if DART_RESTRICTED_HEADERS.contains(&name.to_lowercase().as_str()) {
                continue;
            }
            if name.to_lowercase() == "content-type" {
                continue; // Already handled above.
            }
            let escaped_name = escape_dart(&name.to_lowercase());
            let escaped_value = escape_dart(value);
            let _ = writeln!(out, "    ioReq.headers.set('{escaped_name}', '{escaped_value}');");
        }

        // Add cookies.
        if !ctx.cookies.is_empty() {
            let mut cookie_pairs: Vec<(&String, &String)> = ctx.cookies.iter().collect();
            cookie_pairs.sort_by_key(|(k, _)| k.as_str());
            let cookie_str: Vec<String> = cookie_pairs.iter().map(|(k, v)| format!("{k}={v}")).collect();
            let cookie_header = escape_dart(&cookie_str.join("; "));
            let _ = writeln!(out, "    ioReq.headers.set('cookie', '{cookie_header}');");
        }

        // Write body bytes if present (bypass charset-based encoding issues).
        if let Some(body) = ctx.body {
            let json_str = serde_json::to_string(body).unwrap_or_default();
            let escaped = escape_dart(&json_str);
            let _ = writeln!(out, "    final bodyBytes = utf8.encode('{escaped}');");
            let _ = writeln!(out, "    ioReq.add(bodyBytes);");
        }

        let _ = writeln!(out, "    final ioResp = await ioReq.close();");
        // Drain the response body to bind `bodyStr` for assertion primitives and to
        // allow the server to cleanly close the connection (prevents RST packets).
        // Redirect responses have no body to drain — skip to avoid a potential hang.
        if !self.is_redirect.get() {
            let _ = writeln!(out, "    final bodyStr = await ioResp.transform(utf8.decoder).join();");
        };
    }

    fn render_assert_status(&self, out: &mut String, _response_var: &str, status: u16) {
        let _ = writeln!(
            out,
            "    expect(ioResp.statusCode, equals({status}), reason: 'status code mismatch');"
        );
    }

    /// Emit a single header assertion, handling special tokens `<<present>>`,
    /// `<<absent>>`, and `<<uuid>>`.
    fn render_assert_header(&self, out: &mut String, _response_var: &str, name: &str, expected: &str) {
        let escaped_name = escape_dart(&name.to_lowercase());
        match expected {
            "<<present>>" => {
                let _ = writeln!(
                    out,
                    "    expect(ioResp.headers.value('{escaped_name}'), isNotNull, reason: 'header {escaped_name} should be present');"
                );
            }
            "<<absent>>" => {
                let _ = writeln!(
                    out,
                    "    expect(ioResp.headers.value('{escaped_name}'), isNull, reason: 'header {escaped_name} should be absent');"
                );
            }
            "<<uuid>>" => {
                let _ = writeln!(
                    out,
                    "    expect(ioResp.headers.value('{escaped_name}'), matches(RegExp(r'^[0-9a-f]{{8}}-[0-9a-f]{{4}}-[0-9a-f]{{4}}-[0-9a-f]{{4}}-[0-9a-f]{{12}}$')), reason: 'header {escaped_name} should be a UUID');"
                );
            }
            exact => {
                let escaped_value = escape_dart(exact);
                let _ = writeln!(
                    out,
                    "    expect(ioResp.headers.value('{escaped_name}'), contains('{escaped_value}'), reason: 'header {escaped_name} mismatch');"
                );
            }
        }
    }

    /// Emit an exact-equality body assertion.
    ///
    /// String bodies are compared as decoded text; structured JSON bodies are
    /// compared via `jsonDecode`.
    fn render_assert_json_body(&self, out: &mut String, _response_var: &str, expected: &serde_json::Value) {
        match expected {
            serde_json::Value::Object(_) | serde_json::Value::Array(_) => {
                let json_str = serde_json::to_string(expected).unwrap_or_default();
                let escaped = escape_dart(&json_str);
                let _ = writeln!(out, "    final bodyJson = jsonDecode(bodyStr);");
                let _ = writeln!(out, "    final expectedJson = jsonDecode('{escaped}');");
                let _ = writeln!(
                    out,
                    "    expect(bodyJson, equals(expectedJson), reason: 'body mismatch');"
                );
            }
            serde_json::Value::String(s) => {
                let escaped = escape_dart(s);
                let _ = writeln!(
                    out,
                    "    expect(bodyStr.trim(), equals('{escaped}'), reason: 'body mismatch');"
                );
            }
            other => {
                let escaped = escape_dart(&other.to_string());
                let _ = writeln!(
                    out,
                    "    expect(bodyStr.trim(), equals('{escaped}'), reason: 'body mismatch');"
                );
            }
        }
    }

    /// Emit partial-body assertions — every key in `expected` must match the
    /// corresponding field in the parsed JSON response.
    fn render_assert_partial_body(&self, out: &mut String, _response_var: &str, expected: &serde_json::Value) {
        let _ = writeln!(
            out,
            "    final partialJson = jsonDecode(bodyStr) as Map<String, dynamic>;"
        );
        if let Some(obj) = expected.as_object() {
            for (idx, (key, val)) in obj.iter().enumerate() {
                let escaped_key = escape_dart(key);
                let json_val = serde_json::to_string(val).unwrap_or_default();
                let escaped_val = escape_dart(&json_val);
                // Use an index-based variable name so keys with special characters
                // don't produce invalid Dart identifiers.
                let _ = writeln!(out, "    final _expectedField{idx} = jsonDecode('{escaped_val}');");
                let _ = writeln!(
                    out,
                    "    expect(partialJson['{escaped_key}'], equals(_expectedField{idx}), reason: 'partial body field \\'{escaped_key}\\' mismatch');"
                );
            }
        }
    }

    /// Emit validation-error assertions for 422 responses.
    fn render_assert_validation_errors(
        &self,
        out: &mut String,
        _response_var: &str,
        errors: &[ValidationErrorExpectation],
    ) {
        let _ = writeln!(out, "    final errBody = jsonDecode(bodyStr) as Map<String, dynamic>;");
        let _ = writeln!(out, "    final errList = (errBody['errors'] ?? []) as List<dynamic>;");
        for ve in errors {
            let loc_dart: Vec<String> = ve.loc.iter().map(|s| format!("'{}'", escape_dart(s))).collect();
            let loc_str = loc_dart.join(", ");
            let escaped_msg = escape_dart(&ve.msg);
            let _ = writeln!(
                out,
                "    expect(errList.any((e) => e is Map && (e['loc'] as List?)?.join(',') == [{loc_str}].join(',') && (e['msg'] as String? ?? '').contains('{escaped_msg}')), isTrue, reason: 'validation error not found: {escaped_msg}');"
            );
        }
    }
}

/// Render a `package:test` `test(...)` block for an HTTP server fixture.
///
/// Delegates to the shared [`client::http_call::render_http_test`] driver via
/// [`DartTestClientRenderer`]. HTTP 101 (WebSocket upgrade) fixtures are emitted
/// as skip stubs before reaching the driver because `dart:io HttpClient` cannot
/// handle protocol-switch responses.
fn render_http_test_case(out: &mut String, fixture: &Fixture, http: &HttpFixture) {
    // HTTP 101 (WebSocket upgrade) — dart:io HttpClient cannot handle upgrade responses.
    if http.expected_response.status_code == 101 {
        let description = escape_dart(&fixture.description);
        let _ = writeln!(out, "  test('{description}', () {{");
        let _ = writeln!(
            out,
            "    markTestSkipped('Skipped: Dart HttpClient cannot handle 101 Switching Protocols responses');"
        );
        let _ = writeln!(out, "  }});");
        let _ = writeln!(out);
        return;
    }

    // Pre-set `is_redirect` on the renderer so `render_call` can inject
    // `ioReq.followRedirects = false` for 3xx fixtures. The shared driver has no
    // concept of expected status code so we thread it through renderer state.
    let is_redirect = http.expected_response.status_code / 100 == 3;
    client::http_call::render_http_test(out, &DartTestClientRenderer::new(is_redirect), fixture);
}

/// Emit a compilable skip stub for non-HTTP fixtures without a dart call override.
fn render_skip_stub(out: &mut String, fixture: &Fixture) {
    let description = escape_dart(&fixture.description);
    let fixture_id = &fixture.id;
    let _ = writeln!(out, "  test('{description}', () {{");
    let _ = writeln!(
        out,
        "    markTestSkipped('TODO: implement Dart e2e test for fixture \\'{fixture_id}\\'');"
    );
    let _ = writeln!(out, "  }});");
    let _ = writeln!(out);
}

/// Escape a string for embedding in a Dart single-quoted string literal.
fn escape_dart(s: &str) -> String {
    s.replace('\\', "\\\\")
        .replace('\'', "\\'")
        .replace('\n', "\\n")
        .replace('\r', "\\r")
        .replace('\t', "\\t")
        .replace('$', "\\$")
}