Added randomized simulation parameters generation

[leobragaz]

After I integrated wasmd inside desmos I found out that the simulation tests fails due to the fact that the RandomizedParams function of module.go returns nil.

--- FAIL: TestAppImportExport (128.47s)
panic: UnmarshalJSON cannot decode empty bytes [recovered]
	panic: UnmarshalJSON cannot decode empty bytes

In order to solve this I added the simulation folder with the params generation and the randomized genesis that will be called inside the tests. This could be useful for those projects that run sims.

Closes #392.

[codecov]

Codecov Report

Merging #389 (e975efd) into master (4141cc3) will decrease coverage by 0.06%.
The diff coverage is 50.00%.

@@            Coverage Diff             @@
##           master     #389      +/-   ##
==========================================
- Coverage   55.42%   55.35%   -0.07%     
==========================================
  Files          39       39              
  Lines        4018     4021       +3     
==========================================
- Hits         2227     2226       -1     
- Misses       1612     1615       +3     
- Partials      179      180       +1     

Impacted Files	Coverage Δ
x/wasm/module.go	49.09% <33.33%> (+0.03%)	⬆️
app/app.go	87.74% <66.66%> (-0.35%)	⬇️
x/wasm/internal/keeper/keeper.go	88.36% <0.00%> (-0.56%)	⬇️

[ethanfrey]

Looks fine to me, but I don't understand the simulation system.

I'd love @alpe to take a quick look before merging.

[alpe]

Thank you very much for adding these simulation data generators! 🌻
I have run them locally but ended up with failures. Please see my comments to fix the return types.

[ethanfrey]

Since this is not used by wasmd internally, I would ask you to submit working test cases for simulation to wasmd (so we could at least manually validate it is correct). We won't focus much more energy on this PR, but happy to merge if it gets working, and then include it in the next release.

We are making a 0.15.0 with the new cosmos-sdk v0.41.0.
Happy to make a 0.15.1 point release with sims when it is working

[leobragaz]

Thanks @alpe! Can I ask which tests did you run to end up with failures?

[alpe]

Thanks @alpe! Can I ask which tests did you run to end up with failures?

In case somebody is following this PR. We talked on discord to move this forward. https://discord.com/channels/737637324434833438/737640672680607764/804352247026417724

[alpe]

Thanks again for the updates. 🤗 Only some minor comments on the code although I could not make it work on my machine. It fails with a panic and no helpful errors.

ERROR OUTPUT

exit status 1
panic: halting simulations
goroutine 36 [running]:
main.worker(0x1, 0xc000074a20, 0xc00028e000)
	/Users/alex/go/pkg/mod/github.com/cosmos/tools/cmd/runsim@v1.0.0/main.go:216 +0x7a5
main.main.func2(0xc0002a2010, 0xc000074a20, 0xc00028e000, 0x1)
	/Users/alex/go/pkg/mod/github.com/cosmos/tools/cmd/runsim@v1.0.0/main.go:160 +0x6b
created by main.main
	/Users/alex/go/pkg/mod/github.com/cosmos/tools/cmd/runsim@v1.0.0/main.go:158 +0xc1a
make: *** [test-sim-import-export] Error 2

Does it work for you?

[leobragaz]

Thanks again for the updates. 🤗 Only some minor comments on the code although I could not make it work on my machine. It fails with a panic and no helpful errors.

ERROR OUTPUT

exit status 1
panic: halting simulations
goroutine 36 [running]:
main.worker(0x1, 0xc000074a20, 0xc00028e000)
	/Users/alex/go/pkg/mod/github.com/cosmos/tools/cmd/runsim@v1.0.0/main.go:216 +0x7a5
main.main.func2(0xc0002a2010, 0xc000074a20, 0xc00028e000, 0x1)
	/Users/alex/go/pkg/mod/github.com/cosmos/tools/cmd/runsim@v1.0.0/main.go:160 +0x6b
created by main.main
	/Users/alex/go/pkg/mod/github.com/cosmos/tools/cmd/runsim@v1.0.0/main.go:158 +0xc1a
make: *** [test-sim-import-export] Error 2

Does it work for you?

@alpe
Above those cryptic lines you should also see this line:

Seed 7: FAILED
To reproduce run: go test ./app -run TestAppImportExport -Enabled=true -NumBlocks=50 -Genesis= -Verbose=true -Commit=true -Seed=7 -Period=5 -ExportParamsPath /var/folders/xs/g0l3kxkx5msct63qbx9shlsr0000gn/T/sim-logs-833631974/sim_params-7.json -ExportStatePath /var/folders/xs/g0l3kxkx5msct63qbx9shlsr0000gn/T/sim-logs-833631974/sim_state-7.json -v -timeout 24h
ERROR OUTPUT 

If you're using GoLand (or IntelliJ) it's pretty easy to get a clearer error log by editing the configuration of the TestSimAppImportExport by doing these steps:

1. Run the test from within the sim_test.go file
2. Edit the configuration and paste this -Enabled=true -NumBlocks=50 -Genesis= -Verbose=true -Commit=true -Seed=7 -Period=5 -ExportParamsPath /var/folders/xs/g0l3kxkx5msct63qbx9shlsr0000gn/T/sim-logs-833631974/sim_params-7.json -ExportStatePath /var/folders/xs/g0l3kxkx5msct63qbx9shlsr0000gn/T/sim-logs-833631974/sim_state-7.json
   inside Program arguments and -v -timeout 24h inside Go tool arguments like this
3. Re run the configured test

This will print a much meaningful error showing an error on import referring to the capability module.
And that was why I've removed that lines in the first place, but since it will make no difference because it will fail anyway for the same bug (since wasmd is using capability) I'll leave it there where it was before deleting it.

Since it's weird to have a failing test to make sure that params generation works, I've added an extra TestFullAppSimulation that exited with code 0.
For the capability bug I think I will discuss with my team since we will also run into that bug and open an issue into the Cosmos repo.

[alpe]

@bragaz thank you very much for this big effort to integrate simulations. Well done 👏
I will 👀 for the SDK bug fix and discuss how we can integrate them into our release process.