feat(pkg/scale): VaryingDataType String method (#2970)

- Add `String() string` methods to all types implementing `VaryingDataTypeValue`
- Add `String() string` method on `VaryingDataType` struct which tries to use the `VaryingDataTypeValue` String method if present
- Add `String() string` method on `VaryingDataTypeSlice` struct

dot/types/babe_digest.go

@@ -64,6 +64,12 @@ func (d *BabePrimaryPreDigest) ToPreRuntimeDigest() (*PreRuntimeDigest, error) {
 // Index returns VDT index
 func (BabePrimaryPreDigest) Index() uint { return 1 }
 
+func (d BabePrimaryPreDigest) String() string {
+	return fmt.Sprintf("BabePrimaryPreDigest{AuthorityIndex=%d, SlotNumber=%d, "+
+		"VRFOutput=0x%x, VRFProof=0x%x}",
+		d.AuthorityIndex, d.SlotNumber, d.VRFOutput, d.VRFProof)
+}
+
 // BabeSecondaryPlainPreDigest is included in a block built by a secondary slot authorized producer
 type BabeSecondaryPlainPreDigest struct {
 	AuthorityIndex uint32
@@ -86,6 +92,11 @@ func (d *BabeSecondaryPlainPreDigest) ToPreRuntimeDigest() (*PreRuntimeDigest, e
 // Index returns VDT index
 func (BabeSecondaryPlainPreDigest) Index() uint { return 2 }
 
+func (d BabeSecondaryPlainPreDigest) String() string {
+	return fmt.Sprintf("BabeSecondaryPlainPreDigest{AuthorityIndex=%d, SlotNumber: %d}",
+		d.AuthorityIndex, d.SlotNumber)
+}
+
 // BabeSecondaryVRFPreDigest is included in a block built by a secondary slot authorized producer
 type BabeSecondaryVRFPreDigest struct {
 	AuthorityIndex uint32
@@ -114,6 +125,12 @@ func (d *BabeSecondaryVRFPreDigest) ToPreRuntimeDigest() (*PreRuntimeDigest, err
 // Index returns VDT index
 func (BabeSecondaryVRFPreDigest) Index() uint { return 3 }
 
+func (d BabeSecondaryVRFPreDigest) String() string {
+	return fmt.Sprintf("BabeSecondaryVRFPreDigest{AuthorityIndex=%d, SlotNumber=%d, "+
+		"VrfOutput=0x%x, VrfProof=0x%x",
+		d.AuthorityIndex, d.SlotNumber, d.VrfOutput, d.VrfProof)
+}
+
 // toPreRuntimeDigest returns the VaryingDataTypeValue as a PreRuntimeDigest
 func toPreRuntimeDigest(value scale.VaryingDataTypeValue) (*PreRuntimeDigest, error) {
 	digest := NewBabeDigest()

dot/types/consensus_digest.go

@@ -29,6 +29,10 @@ type GrandpaScheduledChange struct {
 // Index returns VDT index
 func (GrandpaScheduledChange) Index() uint { return 1 }
 
+func (g GrandpaScheduledChange) String() string {
+	return fmt.Sprintf("GrandpaScheduledChange{Auths=%v, Delay=%d", g.Auths, g.Delay)
+}
+
 // GrandpaForcedChange represents a GRANDPA forced authority change
 type GrandpaForcedChange struct {
 	// BestFinalizedBlock is specified by the governance mechanism, defines
@@ -42,6 +46,11 @@ type GrandpaForcedChange struct {
 // Index returns VDT index
 func (GrandpaForcedChange) Index() uint { return 2 }
 
+func (g GrandpaForcedChange) String() string {
+	return fmt.Sprintf("GrandpaForcedChange{BestFinalizedBlock=%d, Auths=%v, Delay=%d",
+		g.BestFinalizedBlock, g.Auths, g.Delay)
+}
+
 // GrandpaOnDisabled represents a GRANDPA authority being disabled
 type GrandpaOnDisabled struct {
 	ID uint64
@@ -50,6 +59,10 @@ type GrandpaOnDisabled struct {
 // Index returns VDT index
 func (GrandpaOnDisabled) Index() uint { return 3 }
 
+func (g GrandpaOnDisabled) String() string {
+	return fmt.Sprintf("GrandpaOnDisabled{ID=%d}", g.ID)
+}
+
 // GrandpaPause represents an authority set pause
 type GrandpaPause struct {
 	Delay uint32
@@ -58,6 +71,10 @@ type GrandpaPause struct {
 // Index returns VDT index
 func (GrandpaPause) Index() uint { return 4 }
 
+func (g GrandpaPause) String() string {
+	return fmt.Sprintf("GrandpaPause{Delay=%d}", g.Delay)
+}
+
 // GrandpaResume represents an authority set resume
 type GrandpaResume struct {
 	Delay uint32
@@ -66,6 +83,10 @@ type GrandpaResume struct {
 // Index returns VDT index
 func (GrandpaResume) Index() uint { return 5 }
 
+func (g GrandpaResume) String() string {
+	return fmt.Sprintf("GrandpaResume{Delay=%d}", g.Delay)
+}
+
 // NextEpochData is the digest that contains the data for the upcoming BABE epoch.
 // It is included in the first block of every epoch to describe the next epoch.
 type NextEpochData struct {
@@ -101,6 +122,10 @@ type BABEOnDisabled struct {
 // Index returns VDT index
 func (BABEOnDisabled) Index() uint { return 2 }
 
+func (b BABEOnDisabled) String() string {
+	return fmt.Sprintf("BABEOnDisabled{ID=%d}", b.ID)
+}
+
 // NextConfigData is the digest that contains changes to the BABE configuration.
 // It is potentially included in the first block of an epoch to describe the next epoch.
 type NextConfigData struct {
@@ -112,6 +137,11 @@ type NextConfigData struct {
 // Index returns VDT index
 func (NextConfigData) Index() uint { return 3 }
 
+func (d NextConfigData) String() string {
+	return fmt.Sprintf("NextConfigData{C1=%d, C2=%d, SecondarySlots=%d}",
+		d.C1, d.C2, d.SecondarySlots)
+}
+
 // ToConfigData returns the NextConfigData as ConfigData
 func (d *NextConfigData) ToConfigData() *ConfigData {
 	return &ConfigData{

dot/types/digest.go

@@ -48,7 +48,7 @@ type ChangesTrieRootDigest struct {
 func (ChangesTrieRootDigest) Index() uint { return 2 }
 
 // String returns the digest as a string
-func (d *ChangesTrieRootDigest) String() string {
+func (d ChangesTrieRootDigest) String() string {
 	return fmt.Sprintf("ChangesTrieRootDigest Hash=%s", d.Hash)
 }
 
@@ -70,7 +70,7 @@ func NewBABEPreRuntimeDigest(data []byte) *PreRuntimeDigest {
 }
 
 // String returns the digest as a string
-func (d *PreRuntimeDigest) String() string {
+func (d PreRuntimeDigest) String() string {
 	return fmt.Sprintf("PreRuntimeDigest ConsensusEngineID=%s Data=0x%x", d.ConsensusEngineID.ToBytes(), d.Data)
 }
 
@@ -98,6 +98,6 @@ type SealDigest struct {
 func (SealDigest) Index() uint { return 5 }
 
 // String returns the digest as a string
-func (d *SealDigest) String() string {
+func (d SealDigest) String() string {
 	return fmt.Sprintf("SealDigest ConsensusEngineID=%s Data=0x%x", d.ConsensusEngineID.ToBytes(), d.Data)
 }

dot/types/grandpa.go

@@ -17,6 +17,10 @@ type GrandpaAuthoritiesRaw struct {
 	ID  uint64
 }
 
+func (g GrandpaAuthoritiesRaw) String() string {
+	return fmt.Sprintf("GrandpaAuthoritiesRaw{Key=0x%x, ID=%d}", g.Key, g.ID)
+}
+
 // FromRawEd25519 sets the Authority given GrandpaAuthoritiesRaw. It converts the byte representations of
 // the authority public keys into a ed25519.PublicKey.
 func (a *Authority) FromRawEd25519(raw GrandpaAuthoritiesRaw) error {
@@ -189,7 +193,6 @@ type GrandpaVote struct {
 	Number uint32
 }
 
-// String returns the Vote as a string
-func (v *GrandpaVote) String() string {
+func (v GrandpaVote) String() string {
 	return fmt.Sprintf("hash=%s number=%d", v.Hash, v.Number)
 }

lib/babe/errors.go

@@ -130,18 +130,24 @@ type Other string
 // Index returns VDT index
 func (Other) Index() uint { return 0 }
 
+func (o Other) String() string { return string(o) }
+
 // CannotLookup Failed to lookup some data
 type CannotLookup struct{}
 
 // Index returns VDT index
 func (CannotLookup) Index() uint { return 1 }
 
+func (CannotLookup) String() string { return "cannot lookup" }
+
 // BadOrigin A bad origin
 type BadOrigin struct{}
 
 // Index returns VDT index
 func (BadOrigin) Index() uint { return 2 }
 
+func (BadOrigin) String() string { return "bad origin" }
+
 // Module A custom error in a module
 type Module struct {
 	Idx     uint8
@@ -152,8 +158,12 @@ type Module struct {
 // Index returns VDT index
 func (Module) Index() uint { return 3 }
 
-func (err Module) string() string {
-	return fmt.Sprintf("index: %d code: %d message: %x", err.Idx, err.Err, *err.Message)
+func (err Module) String() string {
+	message := "nil"
+	if err.Message != nil {
+		message = *err.Message
+	}
+	return fmt.Sprintf("Module{Idx=%d, Err=%d Message=%s", err.Idx, err.Err, message)
 }
 
 // ValidityCannotLookup Could not lookup some information that is required to validate the transaction
@@ -162,78 +172,104 @@ type ValidityCannotLookup struct{}
 // Index returns VDT index
 func (ValidityCannotLookup) Index() uint { return 0 }
 
+func (ValidityCannotLookup) String() string { return "validity cannot lookup" }
+
 // NoUnsignedValidator No validator found for the given unsigned transaction
 type NoUnsignedValidator struct{}
 
 // Index returns VDT index
 func (NoUnsignedValidator) Index() uint { return 1 }
 
+func (NoUnsignedValidator) String() string { return "no unsigned validator" }
+
 // UnknownCustom Any other custom unknown validity that is not covered
 type UnknownCustom uint8
 
 // Index returns VDT index
 func (UnknownCustom) Index() uint { return 2 }
 
+func (uc UnknownCustom) String() string { return fmt.Sprintf("UnknownCustom(%d)", uc) }
+
 // Call The call of the transaction is not expected
 type Call struct{}
 
 // Index returns VDT index
 func (Call) Index() uint { return 0 }
 
+func (Call) String() string { return "call" }
+
 // Payment General error to do with the inability to pay some fees (e.g. account balance too low)
 type Payment struct{}
 
 // Index returns VDT index
 func (Payment) Index() uint { return 1 }
 
+func (Payment) String() string { return "payment" }
+
 // Future General error to do with the transaction not yet being valid (e.g. nonce too high)
 type Future struct{}
 
 // Index returns VDT index
 func (Future) Index() uint { return 2 }
 
+func (Future) String() string { return "future" }
+
 // Stale General error to do with the transaction being outdated (e.g. nonce too low)
 type Stale struct{}
 
 // Index returns VDT index
 func (Stale) Index() uint { return 3 }
 
+func (Stale) String() string { return "stale" }
+
 // BadProof General error to do with the transaction’s proofs (e.g. signature)
 type BadProof struct{}
 
 // Index returns VDT index
 func (BadProof) Index() uint { return 4 }
 
+func (BadProof) String() string { return "bad proof" }
+
 // AncientBirthBlock The transaction birth block is ancient
 type AncientBirthBlock struct{}
 
 // Index returns VDT index
 func (AncientBirthBlock) Index() uint { return 5 }
 
+func (AncientBirthBlock) String() string { return "ancient birth block" }
+
 // ExhaustsResources The transaction would exhaust the resources of current block
 type ExhaustsResources struct{}
 
 // Index returns VDT index
 func (ExhaustsResources) Index() uint { return 6 }
 
+func (ExhaustsResources) String() string { return "exhausts resources" }
+
 // InvalidCustom Any other custom invalid validity that is not covered
 type InvalidCustom uint8
 
 // Index returns VDT index
 func (InvalidCustom) Index() uint { return 7 }
 
+func (ic InvalidCustom) String() string { return fmt.Sprintf("InvalidCustom(%d)", ic) }
+
 // BadMandatory An extrinsic with a Mandatory dispatch resulted in Error
 type BadMandatory struct{}
 
 // Index returns VDT index
 func (BadMandatory) Index() uint { return 8 }
 
+func (BadMandatory) String() string { return "bad mandatory" }
+
 // MandatoryDispatch A transaction with a mandatory dispatch
 type MandatoryDispatch struct{}
 
 // Index returns VDT index
 func (MandatoryDispatch) Index() uint { return 9 }
 
+func (MandatoryDispatch) String() string { return "mandatory dispatch" }
+
 func determineErrType(vdt scale.VaryingDataType) error {
 	vdtVal, err := vdt.Value()
 	if err != nil {
@@ -247,7 +283,7 @@ func determineErrType(vdt scale.VaryingDataType) error {
 	case BadOrigin:
 		return &DispatchOutcomeError{"bad origin"}
 	case Module:
-		return &DispatchOutcomeError{fmt.Sprintf("custom module error: %s", val.string())}
+		return &DispatchOutcomeError{fmt.Sprintf("custom module error: %s", val)}
 	case Call:
 		return &TransactionValidityError{errUnexpectedTxCall}
 	case Payment:

lib/babe/errors_test.go

@@ -23,12 +23,12 @@ func TestApplyExtrinsicErrors(t *testing.T) {
 		{
 			name:     "Dispatch custom module error empty",
 			test:     []byte{0, 1, 3, 4, 5, 1, 0},
-			expected: "dispatch outcome error: custom module error: index: 4 code: 5 message: ",
+			expected: "dispatch outcome error: custom module error: Module{Idx=4, Err=5 Message=",
 		},
 		{
 			name:     "Dispatch custom module error",
 			test:     []byte{0, 1, 3, 4, 5, 1, 0x04, 0x65},
-			expected: "dispatch outcome error: custom module error: index: 4 code: 5 message: 65",
+			expected: "dispatch outcome error: custom module error: Module{Idx=4, Err=5 Message=e",
 		},
 		{
 			name:     "Dispatch unknown error",