Benchmark tool: add option for build repo to benchmark against. (#3808)

* Benchmark tool: add option for build repo to benchmark against.

* Address review comments.

Author: davidmorgan

_benchmark/README.md

@@ -4,5 +4,14 @@ Benchmarks `build_runner` against synthetic codebases applying real generators:
 Example usage:
 
 ```
-dart run _benchmark --generator=built_value benchmark
+# Benchmark `build_runner` from pub.
+dart run _benchmark \
+    --generator=built_value \
+    benchmark
+
+# Benchmark a local version of `build_runner`.
+dart run _benchmark \
+    --generator=built_value \
+    --build-repo-path=$PWD/.. \
+    benchmark
 ```

_benchmark/bin/_benchmark.dart

@@ -16,6 +16,10 @@ final commandRunner =
       ..addCommand(BenchmarkCommand())
       ..addCommand(MeasureCommand())
       ..addCommand(CreateCommand())
+      ..argParser.addOption(
+        'build-repo-path',
+        help: 'Path to build repo to benchmark.',
+      )
       ..argParser.addOption(
         'generator',
         help: 'Generator to benchmark.',

_benchmark/lib/benchmarks/built_value_generator_benchmark.dart

@@ -33,6 +33,8 @@ dependencies:
 dev_dependencies:
   build_runner: any
   built_value_generator: any
+  
+${config.dependencyOverrides}
 ''',
     );
 

_benchmark/lib/benchmarks/freezed_generator_benchmark.dart

@@ -33,6 +33,8 @@ dependencies:
 dev_dependencies:
   build_runner: any
   freezed: any
+
+${config.dependencyOverrides}
 ''',
     );
 

_benchmark/lib/benchmarks/json_serializable_generator_benchmark.dart

@@ -34,6 +34,8 @@ dependencies:
 dev_dependencies:
   build_runner: any
   json_serializable: any
+
+${config.dependencyOverrides}
 ''',
     );
 

_benchmark/lib/benchmarks/mockito_generator_benchmark.dart

@@ -35,6 +35,8 @@ dependencies:
 
 dev_dependencies:
   build_runner: any
+
+${config.dependencyOverrides}
 ''',
     );
 

_benchmark/lib/config.dart

@@ -11,13 +11,19 @@ import 'workspace.dart';
 
 /// Benchmark tool config.
 class Config {
+  final String? buildRepoPath;
   final Generator generator;
   final Directory rootDirectory;
   final List<int> sizes = const [1, 100, 250, 500, 750, 1000];
 
-  Config({required this.generator, required this.rootDirectory});
+  Config({
+    required this.buildRepoPath,
+    required this.generator,
+    required this.rootDirectory,
+  });
 
   factory Config.fromArgResults(ArgResults argResults) => Config(
+    buildRepoPath: argResults['build-repo-path'] as String?,
     generator: Generator.values.singleWhere(
       (e) => e.packageName == argResults['generator'],
     ),
@@ -41,4 +47,29 @@ class RunConfig {
     required this.size,
     required this.paddedSize,
   });
+
+  String get dependencyOverrides {
+    final buildRepoPath = config.buildRepoPath;
+    if (buildRepoPath == null) return '';
+
+    return '''
+dependency_overrides:
+  build:
+    path: $buildRepoPath/build
+  build_config:
+    path: $buildRepoPath/build_config
+  build_modules:
+    path: $buildRepoPath/build_modules
+  build_resolvers:
+    path: $buildRepoPath/build_resolvers
+  build_runner:
+    path: $buildRepoPath/build_runner
+  build_runner_core:
+    path: $buildRepoPath/build_runner_core
+  build_test:
+    path: $buildRepoPath/build_test
+  build_web_compilers:
+    path: $buildRepoPath/build_web_compilers
+''';
+  }
 }