Merge #2667

2667: Add property test for `UTxOIndex.selectRandomWithPriority`. r=jonathanknowles a=jonathanknowles

# Issue Number

ADP-890

# Overview

This PR adds a property test for `UTxOIndex.selectRandomWithPriority`.

The `selectRandomWithPriority`  function is designed to:
- select an entry at random from a UTxO index according to a specified list of filter conditions;
- traverse the specified list of filter conditions in order of priority **_from left to right_**.

The test added in this PR provides a basic sanity check to verify that priority order is respected.

# Sample Output

```hs
Cardano.Wallet.Primitive.Types.UTxOIndex
  Indexed UTxO set properties
    Index Selection
      prop_selectRandomWithPriority
        +++ OK, passed 1600 tests:
        59.69% have match for neither asset 1 nor asset 2
        17.12% have match for asset 1 but not for asset 2
        16.31% have match for asset 2 but not for asset 1
         6.88% have match for both asset 1 and asset 2

Finished in 1.0870 seconds
1 example, 0 failures
```

# QA Due Diligence

I ran this test 500 times to increase confidence that it will not fail spuriously. No failures were encountered.


Co-authored-by: Jonathan Knowles <jonathan.knowles@iohk.io>

lib/core/test/unit/Cardano/Wallet/Primitive/Types/UTxOIndexSpec.hs

@@ -35,6 +35,8 @@ import Data.Generics.Internal.VL.Lens
     ( view )
 import Data.Generics.Labels
     ()
+import Data.List.NonEmpty
+    ( NonEmpty (..) )
 import Data.Maybe
     ( isJust, isNothing )
 import Data.Ratio
@@ -55,9 +57,11 @@ import Test.QuickCheck
     , conjoin
     , counterexample
     , cover
+    , forAll
     , oneof
     , property
     , stdConfidence
+    , suchThat
     , withMaxSuccess
     , (===)
     )
@@ -155,6 +159,8 @@ spec =
             property prop_selectRandom_all_withAsset
         it "prop_selectRandom_all_withAssetOnly" $
             property prop_selectRandom_all_withAssetOnly
+        it "prop_selectRandomWithPriority" $
+            property prop_selectRandomWithPriority
 
     parallel $ describe "Set Selection" $ do
 
@@ -531,6 +537,38 @@ prop_selectRandom_all_withAssetOnly u a = checkCoverage $ monadicIO $ do
     assert $ UTxOIndex.deleteMany (fst <$> selectedEntries) u == u'
     assert $ UTxOIndex.insertMany selectedEntries u' == u
 
+-- | Verify that priority order is respected when selecting with more than
+--   one filter.
+--
+prop_selectRandomWithPriority :: UTxOIndex -> Property
+prop_selectRandomWithPriority u =
+    forAll (genAssetIdSmallRange) $ \a1 ->
+    forAll (genAssetIdSmallRange `suchThat` (/= a1)) $ \a2 ->
+    checkCoverage $ monadicIO $ do
+        haveMatchForAsset1 <- isJust <$>
+            run (UTxOIndex.selectRandom u $ WithAssetOnly a1)
+        haveMatchForAsset2 <- isJust <$>
+            run (UTxOIndex.selectRandom u $ WithAssetOnly a2)
+        monitor $ cover 4 (haveMatchForAsset1 && not haveMatchForAsset2)
+            "have match for asset 1 but not for asset 2"
+        monitor $ cover 4 (not haveMatchForAsset1 && haveMatchForAsset2)
+            "have match for asset 2 but not for asset 1"
+        monitor $ cover 4 (haveMatchForAsset1 && haveMatchForAsset2)
+            "have match for both asset 1 and asset 2"
+        monitor $ cover 4 (not haveMatchForAsset1 && not haveMatchForAsset2)
+            "have match for neither asset 1 nor asset 2"
+        result <- run $ UTxOIndex.selectRandomWithPriority u $
+            WithAssetOnly a1 :| [WithAssetOnly a2]
+        case result of
+            Just ((_, o), _) | o `txOutHasAsset` a1 -> do
+                assert haveMatchForAsset1
+            Just ((_, o), _) | o `txOutHasAsset` a2 -> do
+                assert (not haveMatchForAsset1)
+                assert haveMatchForAsset2
+            _ -> do
+                assert (not haveMatchForAsset1)
+                assert (not haveMatchForAsset2)
+
 --------------------------------------------------------------------------------
 -- Set selection properties
 --------------------------------------------------------------------------------