Add a unit test on the invariant

x/collection/keeper/invariants_test.go

@@ -0,0 +1,30 @@
+package keeper_test
+
+import (
+	sdk "github.com/Finschia/finschia-sdk/types"
+	"github.com/Finschia/finschia-sdk/x/collection/keeper"
+)
+
+func (s *KeeperTestSuite) TestTotalSupplyInvariant() {
+	testCases := map[string]struct {
+		malleate func(ctx sdk.Context)
+		valid    bool
+	}{
+		"invariant not broken": {
+			valid: true,
+		},
+	}
+
+	for name, tc := range testCases {
+		s.Run(name, func() {
+			ctx, _ := s.ctx.CacheContext()
+			if tc.malleate != nil {
+				tc.malleate(ctx)
+			}
+
+			invariant := keeper.TotalFTSupplyInvariant(s.keeper)
+			_, broken := invariant(ctx)
+			s.Require().Equal(!tc.valid, broken)
+		})
+	}
+}