fix(sims): TestAppSimulationAfterImport and legacy proposal handling (backport #21800) (#21805)

Co-authored-by: Alexander Peters <alpe@users.noreply.github.com>

simsx/msg_factory.go

@@ -6,13 +6,41 @@ import (
 	sdk "github.com/cosmos/cosmos-sdk/types"
 )
 
+// SimMsgFactoryX is an interface for creating and handling fuzz test-like simulation messages in the system.
 type SimMsgFactoryX interface {
+	// MsgType returns an empty instance of the concrete message type that the factory provides.
+	// This instance is primarily used for deduplication and reporting purposes.
+	// The result must not be nil
 	MsgType() sdk.Msg
+
+	// Create returns a FactoryMethod implementation which is responsible for constructing new instances of the message
+	// on each invocation.
 	Create() FactoryMethod
+
+	// DeliveryResultHandler returns a SimDeliveryResultHandler instance which processes the delivery
+	// response error object. While most simulation factories anticipate successful message delivery,
+	// certain factories employ this handler to validate execution errors, thereby covering negative
+	// test scenarios.
 	DeliveryResultHandler() SimDeliveryResultHandler
 }
+
 type (
-	// FactoryMethod method signature that is implemented by the concrete message factories
+	// FactoryMethod is a method signature implemented by concrete message factories for SimMsgFactoryX
+	//
+	// This factory method is responsible for creating a new `sdk.Msg` instance and determining the
+	// proposed signers who are expected to successfully sign the message for delivery.
+	//
+	// Parameters:
+	// - ctx: The context for the operation
+	// - testData: A pointer to a `ChainDataSource` which provides helper methods and simple access to accounts
+	//   and balances within the chain.
+	// - reporter: An instance of `SimulationReporter` used to report the results of the simulation.
+	//   If no valid message can be provided, the factory method should call `reporter.Skip("some comment")`
+	//   with both `signer` and `msg` set to nil.
+	//
+	// Returns:
+	// - signer: A slice of `SimAccount` representing the proposed signers.
+	// - msg: An instance of `sdk.Msg` representing the message to be delivered.
 	FactoryMethod func(ctx context.Context, testData *ChainDataSource, reporter SimulationReporter) (signer []SimAccount, msg sdk.Msg)
 
 	// FactoryMethodWithFutureOps extended message factory method for the gov module or others that have to schedule operations for a future block.