Add parse constructors for the BenchmarkResults and BenchmarkScore classes (#5614)

packages/web_benchmarks/CHANGELOG.md

@@ -1,3 +1,7 @@
+## 1.0.1
+
+* Adds `parse` constructors for the `BenchmarkResults` and `BenchmarkScore` classes.
+
 ## 1.0.0
 
 * **Breaking change:** replace the `useCanvasKit` parameter in the `serveWebBenchmark`

packages/web_benchmarks/lib/src/benchmark_result.dart

@@ -12,6 +12,16 @@ class BenchmarkScore {
     required this.value,
   });
 
+  /// Deserializes a JSON object to create a [BenchmarkScore] object.
+  factory BenchmarkScore.parse(Map<String, Object?> json) {
+    final String metric = json[_metricKey]! as String;
+    final double value = (json[_valueKey]! as num).toDouble();
+    return BenchmarkScore(metric: metric, value: value);
+  }
+
+  static const String _metricKey = 'metric';
+  static const String _valueKey = 'value';
+
   /// The name of the metric that this score is categorized under.
   ///
   /// Scores collected over time under the same name can be visualized as a
@@ -22,10 +32,10 @@ class BenchmarkScore {
   final num value;
 
   /// Serializes the benchmark metric to a JSON object.
-  Map<String, dynamic> toJson() {
-    return <String, dynamic>{
-      'metric': metric,
-      'value': value,
+  Map<String, Object?> toJson() {
+    return <String, Object?>{
+      _metricKey: metric,
+      _valueKey: value,
     };
   }
 }
@@ -35,22 +45,30 @@ class BenchmarkResults {
   /// Constructs a result containing scores from a single run benchmark run.
   BenchmarkResults(this.scores);
 
+  /// Deserializes a JSON object to create a [BenchmarkResults] object.
+  factory BenchmarkResults.parse(Map<String, Object?> json) {
+    final Map<String, List<BenchmarkScore>> results =
+        <String, List<BenchmarkScore>>{};
+    for (final String key in json.keys) {
+      final List<BenchmarkScore> scores = (json[key]! as List<Object?>)
+          .cast<Map<String, Object?>>()
+          .map(BenchmarkScore.parse)
+          .toList();
+      results[key] = scores;
+    }
+    return BenchmarkResults(results);
+  }
+
   /// Scores collected in a benchmark run.
   final Map<String, List<BenchmarkScore>> scores;
 
   /// Serializes benchmark metrics to JSON.
-  Map<String, List<Map<String, dynamic>>> toJson() {
-    return scores.map<String, List<Map<String, dynamic>>>(
+  Map<String, List<Map<String, Object?>>> toJson() {
+    return scores.map<String, List<Map<String, Object?>>>(
         (String benchmarkName, List<BenchmarkScore> scores) {
-      return MapEntry<String, List<Map<String, dynamic>>>(
+      return MapEntry<String, List<Map<String, Object?>>>(
         benchmarkName,
-        scores
-            .map<Map<String, dynamic>>(
-                (BenchmarkScore score) => <String, dynamic>{
-                      'metric': score.metric,
-                      'value': score.value,
-                    })
-            .toList(),
+        scores.map((BenchmarkScore score) => score.toJson()).toList(),
       );
     });
   }

packages/web_benchmarks/pubspec.yaml

@@ -2,7 +2,7 @@ name: web_benchmarks
 description: A benchmark harness for performance-testing Flutter apps in Chrome.
 repository: https://github.com/flutter/packages/tree/main/packages/web_benchmarks
 issue_tracker: https://github.com/flutter/flutter/issues?q=is%3Aissue+is%3Aopen+label%3A%22p%3A+web_benchmarks%22
-version: 1.0.0
+version: 1.0.1
 
 environment:
   sdk: ">=3.2.0 <4.0.0"

packages/web_benchmarks/test/src/benchmark_result_test.dart

@@ -0,0 +1,52 @@
+// Copyright 2013 The Flutter Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import 'package:flutter_test/flutter_test.dart';
+import 'package:web_benchmarks/server.dart';
+
+void main() {
+  group('can serialize and deserialize', () {
+    test('$BenchmarkResults', () {
+      final Map<String, Object?> data = <String, Object?>{
+        'foo': <Map<String, Object?>>[
+          <String, Object?>{'metric': 'foo.bar', 'value': 12.34},
+          <String, Object?>{'metric': 'foo.baz', 'value': 10},
+        ],
+        'bar': <Map<String, Object?>>[
+          <String, Object?>{'metric': 'bar.foo', 'value': 1.23},
+        ]
+      };
+
+      final BenchmarkResults benchmarkResults = BenchmarkResults.parse(data);
+      expect(benchmarkResults.scores.length, 2);
+      final List<BenchmarkScore> fooBenchmarks =
+          benchmarkResults.scores['foo']!;
+      final List<BenchmarkScore> barBenchmarks =
+          benchmarkResults.scores['bar']!;
+      expect(fooBenchmarks.length, 2);
+      expect(fooBenchmarks[0].metric, 'foo.bar');
+      expect(fooBenchmarks[0].value, 12.34);
+      expect(fooBenchmarks[1].metric, 'foo.baz');
+      expect(fooBenchmarks[1].value, 10);
+      expect(barBenchmarks.length, 1);
+      expect(barBenchmarks[0].metric, 'bar.foo');
+      expect(barBenchmarks[0].value, 1.23);
+
+      expect(benchmarkResults.toJson(), data);
+    });
+
+    test('$BenchmarkScore', () {
+      final Map<String, Object?> data = <String, Object?>{
+        'metric': 'foo',
+        'value': 1.234
+      };
+
+      final BenchmarkScore score = BenchmarkScore.parse(data);
+      expect(score.metric, 'foo');
+      expect(score.value, 1.234);
+
+      expect(score.toJson(), data);
+    });
+  });
+}