flutter build_runner takes too long

Question

I am using EasyLocalization , mobx , JsonSerializable etc. To generate *.g.dart files, I am using build_runner watch or the script in scripts/build.sh :

flutter packages pub run build_runner build

It was taking 2 seconds at most, but then suddenly it started to take at least 10 seconds or sometimes 30 seconds . Because of this situation, build_runner watch became useless, I mean it's not working properly since then.

The output on the console when I run my script:

$ sh scripts/build.sh 
[INFO] Generating build script...
[INFO] Generating build script completed, took 611ms

[INFO] Initializing inputs
[INFO] Reading cached asset graph...
[INFO] Reading cached asset graph completed, took 126ms

[INFO] Checking for updates since last build...
[INFO] Checking for updates since last build completed, took 745ms

[INFO] Running build...
[INFO] 1.2s elapsed, 0/16 actions completed.
[INFO] 2.2s elapsed, 0/16 actions completed.
[INFO] 3.3s elapsed, 0/16 actions completed.
[INFO] 12.5s elapsed, 1/17 actions completed.
[INFO] 13.6s elapsed, 4/20 actions completed.
[INFO] Running build completed, took 14.6s

[INFO] Caching finalized dependency graph...
[INFO] Caching finalized dependency graph completed, took 57ms

[INFO] Succeeded after 14.6s with 2 outputs (47 actions)

Answer 1

I finally decided to try and solve this myself, I've improved it slightly by adding the following to my pubspec.yaml: Eg

targets:
  $default:
    builders:
      json_serializable:
        enabled: true
        generate_for:
          include:
            - lib/your_codegen_folder/**.dart
            - lib/**.gen.dart

Hope this speeds it up a little for you. You'll have to add builder configs for your other two generators like the json_serializable one here. I suspect they might be referred to easy_localization and mobx ? I don't know, I'm new to this.

Answer 2

In addition to avoiding running builders on unnecessary inputs I manage to make my builds MUCH faster by disabling the mockito mock generator, which I was not using:

targets:
  $default:
    builders:
      your_builder:
        generate_for:
          - lib/**/*.dart
      mockito:mockBuilder:
        enabled: false

Running a build was causing Mockito to search every one of my test files for @GenerateMocks.