Fix preloading modules in mix test --slowest-modules=N
#14811
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Before this patch, I have seen the following with some extra debugging
statements and modules with `@on_load` that makes them slow to load:
$ mix test --slowest-modules=5
[lib/mix/tasks/test.ex:614: Mix.Tasks.Test.do_run/3]
app_start_args #=> ["--slowest-modules=5"]
[lib/mix/tasks/app.config.ex:43: Mix.Tasks.App.Config.run/1]
opts[:preload_modules] #=> nil
Running ExUnit with seed: 829176, max_cases: 1
Mod1Test [test/mod1_test.exs]
* test mod1 [L#4]Mod1.__on_load__/0...
Mod1.__on_load__/0 ok
* test mod1 (5004.1ms) [L#4]
Mod2Test [test/mod2_test.exs]
* test mod2 [L#4]Mod2.__on_load__/0...
Mod2.__on_load__/0 ok
* test mod2 (5005.7ms) [L#4]
Finished in 10.0 seconds (10.0s async, 0.00s sync)
Top 5 slowest (10.0s), 99.9% of total time:
Mod2Test (5005.7ms)
[test/mod2_test.exs]
Mod1Test (5004.1ms)
[test/mod1_test.exs]
2 tests, 0 failures
Additionally passing `--preload-modules` fixed the issue.
With this patch, preloading is correctly set.
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Please back port to v1.19 if sounds good. :) |
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💚 💙 💜 💛 ❤️ |
josevalim
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Oct 5, 2025
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Before this patch, I have seen the following with some extra debugging
statements and modules with
@on_loadthat makes them slow to load:Additionally passing
--preload-modulesfixed the issue.With this patch, preloading is correctly set.