feat: Add legacy simapp testing via build tags (#12121)

## Description

This is a PoC just to know what the team thinks of it.

Pros:

- No need to re-write tests
- We make sure that we are running all the same tests on both files

Cons:

- We need to run tests twice (although we would be running them twice if we copy&paste all of them)

Closes: #12068



---

### Author Checklist

*All items are required. Please add a note to the item if the item is not applicable and
please add links to any relevant follow up issues.*

I have...

- [ ] included the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] added `!` to the type prefix if API or client breaking change
- [ ] targeted the correct branch (see [PR Targeting](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#pr-targeting))
- [ ] provided a link to the relevant issue or specification
- [ ] followed the guidelines for [building modules](https://github.com/cosmos/cosmos-sdk/blob/main/docs/building-modules)
- [ ] included the necessary unit and integration [tests](https://github.com/cosmos/cosmos-sdk/blob/main/CONTRIBUTING.md#testing)
- [ ] added a changelog entry to `CHANGELOG.md`
- [ ] included comments for [documenting Go code](https://blog.golang.org/godoc)
- [ ] updated the relevant documentation or specification
- [ ] reviewed "Files changed" and left comments if necessary
- [ ] confirmed all CI checks have passed

### Reviewers Checklist

*All items are required. Please add a note if the item is not applicable and please add
your handle next to the items reviewed if you only reviewed selected items.*

I have...

- [ ] confirmed the correct [type prefix](https://github.com/commitizen/conventional-commit-types/blob/v3.0.0/index.json) in the PR title
- [ ] confirmed `!` in the type prefix if API or client breaking change
- [ ] confirmed all author checklist items have been addressed 
- [ ] reviewed state machine logic
- [ ] reviewed API design and naming
- [ ] reviewed documentation is accurate
- [ ] reviewed tests and test coverage
- [ ] manually tested (if applicable)

.github/workflows/legacy-test.yml

@@ -0,0 +1,152 @@
+name: Legacy App Testing
+on:
+  schedule:
+    - cron: "0 0,12 * * *"
+  release:
+    types: [published]
+
+jobs:
+  cleanup-runs:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: rokroskar/workflow-run-cleanup-action@master
+        env:
+          GITHUB_TOKEN: "${{ secrets.GITHUB_TOKEN }}"
+    if: "!startsWith(github.ref, 'refs/tags/') && github.ref != 'refs/heads/main'"
+  build:
+    runs-on: ubuntu-latest
+    strategy:
+      matrix:
+        go-arch: ["amd64", "arm", "arm64"]
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-go@v3
+        with:
+          go-version: 1.18
+      - name: Build
+        run: GOARCH=${{ matrix.go-arch }} LEDGER_ENABLED=false make build
+
+      - name: Build cosmovisor
+        run: GOARCH=${{ matrix.go-arch }} LEDGER_ENABLED=false make cosmovisor
+
+      - name: Install runsim
+        run: go install github.com/cosmos/tools/cmd/[email protected]
+      - uses: actions/cache@v3
+        with:
+          path: ~/go/bin
+          key: ${{ runner.os }}-go-runsim-binary
+
+  test-submodules:
+    runs-on: ubuntu-latest
+    container: tendermintdev/docker-tm-db-testing
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-go@v3
+        with:
+          go-version: 1.18
+      - name: Run submodule tests and create test coverage profile.
+        # GIT_DIFF is passed to the scripts
+        run: bash scripts/module-tests.sh
+        if: env.GIT_DIFF
+      - uses: actions/upload-artifact@v3
+        with:
+          name: "${{ github.sha }}-go-submodules-coverage"
+          path: ./coverage-go-submod-profile.out
+
+  split-test-files:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-go@v3
+        with:
+          go-version: 1.18
+      - name: Create a file with all core Cosmos SDK pkgs
+        run: go list ./... > pkgs.txt
+      - name: Split pkgs into 4 files
+        run: split -d -n l/4 pkgs.txt pkgs.txt.part.
+      # cache multiple
+      - uses: actions/upload-artifact@v3
+        with:
+          name: "${{ github.sha }}-00"
+          path: ./pkgs.txt.part.00
+      - uses: actions/upload-artifact@v3
+        with:
+          name: "${{ github.sha }}-01"
+          path: ./pkgs.txt.part.01
+      - uses: actions/upload-artifact@v3
+        with:
+          name: "${{ github.sha }}-02"
+          path: ./pkgs.txt.part.02
+      - uses: actions/upload-artifact@v3
+        with:
+          name: "${{ github.sha }}-03"
+          path: ./pkgs.txt.part.03
+
+  tests:
+    runs-on: ubuntu-latest
+    needs: split-test-files
+    strategy:
+      fail-fast: false
+      matrix:
+        part: ["00", "01", "02", "03"]
+    steps:
+      - uses: actions/checkout@v3
+      - uses: actions/setup-go@v3
+        with:
+          go-version: 1.18
+      - uses: actions/download-artifact@v3
+        with:
+          name: "${{ github.sha }}-${{ matrix.part }}"
+        if: env.GIT_DIFF
+      - name: test & coverage report creation
+        run: |
+          cat pkgs.txt.part.${{ matrix.part }} | xargs go test -mod=readonly -timeout 30m -coverprofile=${{ matrix.part }}profile.out -covermode=atomic -tags='legacy_simapp norace ledger test_ledger_mock'
+        if: env.GIT_DIFF
+      - uses: actions/upload-artifact@v3
+        with:
+          name: "${{ github.sha }}-${{ matrix.part }}-coverage"
+          path: ./${{ matrix.part }}profile.out
+
+  sims-notify-success:
+    needs:
+      [tests]
+    runs-on: ubuntu-latest
+    if: ${{ success() }}
+    steps:
+      - name: Check out repository
+        uses: actions/checkout@v3
+
+      - name: Get previous workflow status
+        uses: ./.github/actions/last-workflow-status
+        id: last_status
+        with:
+          github_token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Notify Slack on success
+        if: ${{ steps.last_status.outputs.last_status == 'failure' }}
+        uses: rtCamp/action-slack-notify@12e36fc18b0689399306c2e0b3e0f2978b7f1ee7
+        env:
+          SLACK_WEBHOOK: ${{ secrets.SLACK_WEBHOOK }}
+          SLACK_CHANNEL: cosmos-sdk-legacy-app
+          SLACK_USERNAME: Legacy App Tests
+          SLACK_ICON_EMOJI: ":white_check_mark:"
+          SLACK_COLOR: good
+          SLACK_MESSAGE: Legacy app tests are passing
+          SLACK_FOOTER: ""
+
+  sims-notify-failure:
+    needs:
+      [tests]
+    runs-on: ubuntu-latest
+    if: ${{ failure() }}
+    steps:
+      - name: Notify Slack on failure
+        uses: rtCamp/action-slack-notify@12e36fc18b0689399306c2e0b3e0f2978b7f1ee7
+        env:
+          SLACK_WEBHOOK: ${{ secrets.SLACK_WEBHOOK }}
+          SLACK_CHANNEL: cosmos-sdk-legacy-app
+          SLACK_USERNAME: Legacy App Tests
+          SLACK_ICON_EMOJI: ":skull:"
+          SLACK_COLOR: danger
+          SLACK_MESSAGE: Legacy app tests are failing
+          SLACK_FOOTER: ""

simapp/app.go

@@ -1,3 +1,5 @@
+//go:build !legacy_simapp
+
 package simapp
 
 import (
@@ -151,8 +153,6 @@ type SimApp struct {
 	appCodec          codec.Codec
 	interfaceRegistry codectypes.InterfaceRegistry
 
-	invCheckPeriod uint
-
 	// keys to access the substores
 	keys map[string]*storetypes.KVStoreKey