Fixed bugs and added tests for FlutterMapNetworkImageProvider

lib/src/layer/tile_layer/tile_provider/network_image_provider.dart

@@ -86,8 +86,13 @@ class FlutterMapNetworkImageProvider
             headers: headers,
           ),
         ),
-      );
+      ).catchError((dynamic e) {
+        // ignore: only_throw_errors
+        if (useFallback || fallbackUrl == null) throw e as Object;
+        return _loadAsync(key, chunkEvents, decode, useFallback: true);
+      });
     } catch (_) {
+      // This redundancy necessary, do not remove
       if (useFallback || fallbackUrl == null) rethrow;
       return _loadAsync(key, chunkEvents, decode, useFallback: true);
     }

pubspec.yaml

@@ -38,7 +38,7 @@ dev_dependencies:
   flutter_lints: ^2.0.1
   flutter_test:
     sdk: flutter
-  mocktail: ^0.3.0
+  mocktail: ^1.0.0
   test: ^1.21.4
 
 flutter:

test/layer/tile_layer/tile_provider/network_image_provider_test.dart

@@ -0,0 +1,231 @@
+// ignore_for_file: avoid_print
+
+import 'dart:async';
+import 'dart:convert';
+import 'dart:typed_data';
+
+import 'package:flutter/painting.dart';
+import 'package:flutter/widgets.dart';
+import 'package:flutter_map/src/layer/tile_layer/tile_provider/network_image_provider.dart';
+import 'package:flutter_test/flutter_test.dart';
+import 'package:http/http.dart';
+import 'package:mocktail/mocktail.dart';
+
+import '../../../test_utils/test_tile_image.dart';
+
+class MockHttpClient extends Mock implements BaseClient {}
+
+// Helper function to resolve the ImageInfo from the ImageProvider.
+Future<ImageInfo> getImageInfo(ImageProvider provider) {
+  final completer = Completer<ImageInfo>();
+
+  final ImageStream stream = provider.resolve(ImageConfiguration.empty);
+  stream.addListener(
+    ImageStreamListener(
+      (imageInfo, _) {
+        print('completer.complete($imageInfo)');
+        return completer.complete(imageInfo);
+      },
+      onError: (exception, stackTrace) {
+        print('completer.completeError($exception)');
+        return completer.completeError(exception, stackTrace);
+      },
+    ),
+  );
+
+  return completer.future;
+}
+
+/// Returns a random URL to use for testing. Due to Flutter caching images
+/// we need to use a different URL each time.
+int _urlId = 0;
+Uri randomUrl({bool fallback = false}) {
+  _urlId++;
+  if (fallback) {
+    return Uri.parse('https://example.net/fallback/$_urlId.png');
+  } else {
+    return Uri.parse('https://example.com/main/$_urlId.png');
+  }
+}
+
+void main() {
+  const headers = {
+    'user-agent': 'flutter_map',
+    'x-whatever': '123',
+  };
+
+  const defaultTimeout = Timeout(Duration(seconds: 1));
+
+  setUpAll(() {
+    // Ensure the Mock library has example values for Uri.
+    registerFallbackValue(Uri());
+  });
+
+  // We expect a request to be made to the correct URL with the appropriate headers.
+  testWidgets('test load with correct url/headers', (tester) async {
+    final mockClient = MockHttpClient();
+    final url = randomUrl();
+    when(() => mockClient.readBytes(any(), headers: any(named: 'headers')))
+        .thenAnswer((_) async {
+      print('1');
+      return testWhiteTileBytes;
+    });
+
+    final provider = FlutterMapNetworkImageProvider(
+      url: url.toString(),
+      fallbackUrl: null,
+      headers: headers,
+      httpClient: mockClient,
+    );
+
+    final img = await tester.runAsync(() => getImageInfo(provider));
+    expect(img, isNotNull);
+    expect(img!.image.width, equals(256));
+    expect(img.image.height, equals(256));
+
+    verify(() => mockClient.readBytes(url, headers: headers)).called(1);
+  }, timeout: defaultTimeout);
+
+  // We expect the request to be made, and a HTTP ClientException to be bubbled
+  // up to the caller.
+  testWidgets('test load with server failure (no fallback)', (tester) async {
+    final mockClient = MockHttpClient();
+    final url = randomUrl();
+    when(() => mockClient.readBytes(any(), headers: any(named: 'headers')))
+        .thenAnswer((_) async {
+      print('2');
+      throw ClientException(
+        'Server error',
+      );
+    });
+
+    final provider = FlutterMapNetworkImageProvider(
+      url: url.toString(),
+      fallbackUrl: null,
+      headers: headers,
+      httpClient: mockClient,
+    );
+
+    final img = await tester.runAsync(() => getImageInfo(provider));
+    expect(img, isNull);
+    expect(tester.takeException(), isInstanceOf<ClientException>());
+
+    verify(() => mockClient.readBytes(url, headers: headers)).called(1);
+  }, timeout: defaultTimeout);
+
+  // We expect the regular URL to be called once, then the fallback URL.
+  testWidgets('test load with server error (with successful fallback)',
+      (tester) async {
+    final mockClient = MockHttpClient();
+    final url = randomUrl();
+    when(() => mockClient.readBytes(url, headers: any(named: 'headers')))
+        .thenAnswer((_) async {
+      throw ClientException(
+        'Server error',
+      );
+    });
+    final fallbackUrl = randomUrl(fallback: true);
+    when(() =>
+            mockClient.readBytes(fallbackUrl, headers: any(named: 'headers')))
+        .thenAnswer((_) async {
+      return testWhiteTileBytes;
+    });
+
+    final provider = FlutterMapNetworkImageProvider(
+      url: url.toString(),
+      fallbackUrl: fallbackUrl.toString(),
+      headers: headers,
+      httpClient: mockClient,
+    );
+
+    final img = await tester.runAsync(() => getImageInfo(provider));
+    expect(img, isNotNull);
+    expect(img!.image.width, equals(256));
+    expect(img.image.height, equals(256));
+
+    verify(() => mockClient.readBytes(url, headers: headers)).called(1);
+    verify(() => mockClient.readBytes(fallbackUrl, headers: headers)).called(1);
+  }, timeout: defaultTimeout);
+
+  testWidgets('test load with server error (with failed fallback)',
+      (tester) async {
+    final mockClient = MockHttpClient();
+    final url = randomUrl();
+    final fallbackUrl = randomUrl(fallback: true);
+    when(() => mockClient.readBytes(any(), headers: any(named: 'headers')))
+        .thenAnswer((_) async {
+      throw ClientException(
+        'Server error',
+      );
+    });
+
+    final provider = FlutterMapNetworkImageProvider(
+      url: url.toString(),
+      fallbackUrl: fallbackUrl.toString(),
+      headers: headers,
+      httpClient: mockClient,
+    );
+
+    final img = await tester.runAsync(() => getImageInfo(provider));
+    expect(img, isNull);
+    expect(tester.takeException(), isInstanceOf<ClientException>());
+
+    verify(() => mockClient.readBytes(url, headers: headers)).called(1);
+    verify(() => mockClient.readBytes(fallbackUrl, headers: headers)).called(1);
+  }, timeout: defaultTimeout);
+
+  testWidgets('test load with invalid response (no fallback)', (tester) async {
+    final mockClient = MockHttpClient();
+    final url = randomUrl();
+    when(() => mockClient.readBytes(any(), headers: any(named: 'headers')))
+        .thenAnswer((_) async {
+      // 200 OK with html
+      return Uint8List.fromList(utf8.encode('<html>Server Error</html>'));
+    });
+
+    final provider = FlutterMapNetworkImageProvider(
+      url: url.toString(),
+      fallbackUrl: null,
+      headers: headers,
+      httpClient: mockClient,
+    );
+
+    final img = await tester.runAsync(() => getImageInfo(provider));
+    expect(img, isNull);
+    expect(tester.takeException(), isInstanceOf<Exception>());
+
+    verify(() => mockClient.readBytes(url, headers: headers)).called(1);
+  }, timeout: defaultTimeout);
+
+  testWidgets('test load with invalid response (with successful fallback)',
+      (tester) async {
+    final mockClient = MockHttpClient();
+    final url = randomUrl();
+    when(() => mockClient.readBytes(url, headers: any(named: 'headers')))
+        .thenAnswer((_) async {
+      // 200 OK with html
+      return Uint8List.fromList(utf8.encode('<html>Server Error</html>'));
+    });
+    final fallbackUrl = randomUrl(fallback: true);
+    when(() =>
+            mockClient.readBytes(fallbackUrl, headers: any(named: 'headers')))
+        .thenAnswer((_) async {
+      return testWhiteTileBytes;
+    });
+
+    final provider = FlutterMapNetworkImageProvider(
+      url: url.toString(),
+      fallbackUrl: fallbackUrl.toString(),
+      headers: headers,
+      httpClient: mockClient,
+    );
+
+    final img = await tester.runAsync(() => getImageInfo(provider));
+    expect(img, isNotNull);
+    expect(img!.image.width, equals(256));
+    expect(img.image.height, equals(256));
+
+    verify(() => mockClient.readBytes(url, headers: headers)).called(1);
+    verify(() => mockClient.readBytes(fallbackUrl, headers: headers)).called(1);
+  }, timeout: defaultTimeout);
+}

test/test_utils/test_tile_image.dart

@@ -5,4 +5,5 @@ import 'package:flutter/painting.dart';
 // Base 64 encoded 256x256 white tile.
 const _whiteTile =
     'iVBORw0KGgoAAAANSUhEUgAAAQAAAAEAAQMAAABmvDolAAAAAXNSR0IB2cksfwAAAAlwSFlzAAALEwAACxMBAJqcGAAAAANQTFRF////p8QbyAAAAB9JREFUeJztwQENAAAAwqD3T20ON6AAAAAAAAAAAL4NIQAAAfFnIe4AAAAASUVORK5CYII=';
-final testWhiteTileImage = MemoryImage(base64Decode(_whiteTile));
+final testWhiteTileBytes = base64Decode(_whiteTile);
+final testWhiteTileImage = MemoryImage(testWhiteTileBytes);