Add CannedHttp for testing, HTTP headers in response. (#13)

* Cleanup web socket API, make more idiomatic.

* Export SeltzerWebSocketProvider

* Bump pubspec to 0.1.0-alpha

* Fix.

* Add a CannedHttp implementation for testing.

* Add response headers.

* Fixes.

CHANGELOG.md

@@ -0,0 +1,6 @@
+# Changelog
+
+## 0.2.0-alpha
+
+- Added `CannedHttpResponse` and the `platform/testing.dart` library.
+- Added response headers to `SeltzerHttpResponse`

analysis_options.yaml

@@ -15,7 +15,6 @@ linter:
     - valid_regexps
     - always_declare_return_types
     - annotate_overrides
-    - avoid_as
     - avoid_init_to_null
     - avoid_return_types_on_setters
     - await_only_futures

lib/platform/browser.dart

@@ -46,6 +46,9 @@ class _HtmlSeltzerHttpResponse implements SeltzerHttpResponse {
 
   _HtmlSeltzerHttpResponse(this._request);
 
+  @override
+  Map<String, String> get headers => _request.responseHeaders;
+
   @override
   String get payload => _request.responseText;
 }

lib/platform/server.dart

@@ -37,15 +37,24 @@ class ServerSeltzerHttp extends PlatformSeltzerHttp {
     headers.forEach(request.headers.add);
     var response = await request.close();
     var payload = await UTF8.decodeStream(response);
-    return new _IOSeltzerHttpResponse(payload);
+    var responseHeaders = <String, String>{};
+    response.headers
+        .forEach((name, value) => responseHeaders[name] = value.join(' '));
+    return new _IOSeltzerHttpResponse(
+      payload,
+      new Map<String, String>.unmodifiable(responseHeaders),
+    );
   }
 }
 
 class _IOSeltzerHttpResponse implements SeltzerHttpResponse {
+  @override
+  final Map<String, String> headers;
+
   @override
   final String payload;
 
-  _IOSeltzerHttpResponse(this.payload);
+  _IOSeltzerHttpResponse(this.payload, this.headers);
 }
 
 /// A [SeltzerWebSocket] implementation for the dart vm.

lib/platform/testing.dart

@@ -0,0 +1,65 @@
+import 'dart:async';
+import 'package:seltzer/src/context.dart';
+import 'package:seltzer/src/interface.dart';
+
+/// Initializes `package:seltzer/seltzer.dart` to use an in-memory fake.
+///
+/// In test environments it's useful to have canned responses.
+void useSeltzerForTesting({
+  CannedSeltzerHttp useHttp,
+}) {
+  if (useHttp != null) {
+    setHttpPlatform(useHttp, true);
+  }
+}
+
+/// A fake implementation of [SeltzerHttp].
+///
+/// Use [expect] to add expectations to return canned responses.
+class CannedSeltzerHttp extends PlatformSeltzerHttp {
+  static String _getKey(
+    String method,
+    String url,
+    Map<String, String> headers,
+  ) {
+    return '$method|$url|$headers';
+  }
+
+  final Map<String, _FakeHttpResponse> _expectations =
+      <String, _FakeHttpResponse>{};
+
+  @override
+  Future<SeltzerHttpResponse> execute(
+    String method,
+    String url, {
+    Map<String, String> headers,
+  }) {
+    var response = _expectations.remove(_getKey(method, url, headers));
+    if (response == null) {
+      throw new StateError('No expectation found for $method $url');
+    }
+    return new Future<SeltzerHttpResponse>.value(response);
+  }
+
+  /// Adds an expctation for [method] [url] [requestHeaders].
+  void expect(
+    String method,
+    String url, {
+    Map<String, String> requestHeaders: const {},
+    String response: '',
+    Map<String, String> responseHeaders: const {},
+  }) {
+    _expectations[_getKey(method, url, requestHeaders)] =
+        new _FakeHttpResponse(response, responseHeaders);
+  }
+}
+
+class _FakeHttpResponse implements SeltzerHttpResponse {
+  @override
+  final Map<String, String> headers;
+
+  @override
+  final String payload;
+
+  _FakeHttpResponse(this.payload, this.headers);
+}

lib/src/context.dart

@@ -23,9 +23,9 @@ const _platformAlreadySetError = 'Platform already initialized. In most` '
     'bugs.';
 
 /// Internal method: Initializes the top-level methods to use [platform].
-void setHttpPlatform(SeltzerHttp platform) {
+void setHttpPlatform(SeltzerHttp platform, [bool allowOverride = false]) {
   assert(() {
-    if (_platform != null) {
+    if (!allowOverride && _platform != null) {
       throw new StateError(_platformAlreadySetError);
     }
     return true;

lib/src/interface.dart

@@ -244,6 +244,9 @@ class PlatformSeltzerHttpRequest implements SeltzerHttpRequest {
 
 /// An HTTP response object.
 abstract class SeltzerHttpResponse {
+  /// Response headers.
+  Map<String, String> get headers;
+
   /// Response payload.
   String get payload;
 }

pubspec.yaml

@@ -1,5 +1,5 @@
 name: seltzer
-version: 0.1.0-alpha
+version: 0.2.0-alpha
 description: An elegant and rich cross-platform HTTP library for Dart.
 authors:
   - Matan Lurey <[email protected]>

test/canned_http_test.dart

@@ -0,0 +1,17 @@
+import 'package:seltzer/platform/testing.dart';
+import 'package:test/test.dart';
+
+void main() {
+  test('should fail if an expectation is missing', () {
+    expect(() => new CannedSeltzerHttp().get('/404').send(), throwsStateError);
+  });
+
+  test('should return the canned response', () async {
+    var http = new CannedSeltzerHttp();
+    http.expect('GET', '/fake/url', response: 'Hello World');
+    expect(
+      (await http.get('/fake/url').send().first).payload,
+      'Hello World',
+    );
+  });
+}