Add a treasury growth test

[carbolymer]

Description

Tests that testnet genesis creates treasury which is growing in time.

Checklist

• Commit sequence broadly makes sense and commits have useful messages
• New tests are added if needed and existing tests are updated. These may include:
  • golden tests
  • property tests
  • roundtrip tests
  • integration tests
    See Runnings tests for more details
• Any changes are noted in the CHANGELOG.md for affected package
• The version bounds in .cabal files are updated
• CI passes. See note on CI. The following CI checks are required:
  • Code is linted with hlint. See .github/workflows/check-hlint.yml to get the hlint version
  • Code is formatted with stylish-haskell. See .github/workflows/stylish-haskell.yml to get the stylish-haskell version
  • Code builds on Linux, MacOS and Windows for ghc-8.10.7 and ghc-9.2.7
• Self-reviewed the diff

Note on CI

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You will need to get someone with write privileges. Please contact IOG node developers to do this
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[Jimbo4350]

Why not have this check in the handler? You would only need to check two consecutive epochs and you can do this by taking the length of the state Map EpochNo Integer and comparing the values.

[carbolymer]

This seems to be more clear than combining the epoch treasury values aggregation and check in the same place.

It also checks that nothing weird is not going on - that treasury is suddenly not decreasing after temporary growth.

Moreover, that's a useful debug information to have how the treasury value was changing in the test period if the test fails.

[Jimbo4350]

Shouldn't the case [_] -> True be false since we want to check consecutive epochs?

[carbolymer]

Well, technically a single element set is non-decreasing. A single element set is ruled out by checkHasIncreased, which returns False for [_].