Refactor errors package, so we can do type-checking IsXXErr()

errors/common.go

@@ -5,102 +5,148 @@ package errors
 **/
 
 import (
+	rawerr "errors"
 	"fmt"
 
+	"github.com/pkg/errors"
 	abci "github.com/tendermint/abci/types"
 	"github.com/tendermint/basecoin"
 )
 
-const (
+var (
-	msgDecoding          = "Error decoding input"
+	errDecoding          = rawerr.New("Error decoding input")
-	msgUnauthorized      = "Unauthorized"
+	errUnauthorized      = rawerr.New("Unauthorized")
-	msgInvalidAddress    = "Invalid Address"
+	errInvalidAddress    = rawerr.New("Invalid Address")
-	msgInvalidCoins      = "Invalid Coins"
+	errInvalidCoins      = rawerr.New("Invalid Coins")
-	msgInvalidFormat     = "Invalid Format"
+	errInvalidFormat     = rawerr.New("Invalid Format")
-	msgInvalidSequence   = "Invalid Sequence"
+	errInvalidSequence   = rawerr.New("Invalid Sequence")
-	msgInvalidSignature  = "Invalid Signature"
+	errInvalidSignature  = rawerr.New("Invalid Signature")
-	msgInsufficientFees  = "Insufficient Fees"
+	errInsufficientFees  = rawerr.New("Insufficient Fees")
-	msgInsufficientFunds = "Insufficient Funds"
+	errInsufficientFunds = rawerr.New("Insufficient Funds")
-	msgNoInputs          = "No Input Coins"
+	errNoInputs          = rawerr.New("No Input Coins")
-	msgNoOutputs         = "No Output Coins"
+	errNoOutputs         = rawerr.New("No Output Coins")
-	msgTooLarge          = "Input size too large"
+	errTooLarge          = rawerr.New("Input size too large")
-	msgMissingSignature  = "Signature missing"
+	errMissingSignature  = rawerr.New("Signature missing")
-	msgTooManySignatures = "Too many signatures"
+	errTooManySignatures = rawerr.New("Too many signatures")
-	msgNoChain           = "No chain id provided"
+	errNoChain           = rawerr.New("No chain id provided")
-	msgWrongChain        = "Tx belongs to different chain - %s"
+	errWrongChain        = rawerr.New("Wrong chain for tx")
-	msgUnknownTxType     = "We cannot handle this tx - %v"
+	errUnknownTxType     = rawerr.New("Tx type unknown")
 )
 
-func UnknownTxType(tx basecoin.Tx) TMError {
+func ErrUnknownTxType(tx basecoin.Tx) TMError {
-	msg := fmt.Sprintf(msgUnknownTxType, tx)
+	msg := fmt.Sprintf("%T", tx.Unwrap())
-	return New(msg, abci.CodeType_UnknownRequest)
+	w := errors.Wrap(errUnknownTxType, msg)
+	return WithCode(w, abci.CodeType_UnknownRequest)
 }
 
-func InternalError(msg string) TMError {
+func IsUnknownTxTypeErr(err error) bool {
+	return IsSameError(errUnknownTxType, err)
+}
+
+func ErrInternal(msg string) TMError {
 	return New(msg, abci.CodeType_InternalError)
 }
 
-func DecodingError() TMError {
+// IsInternalErr matches any error that is not classified
-	return New(msgDecoding, abci.CodeType_EncodingError)
+func IsInternalErr(err error) bool {
+	return HasErrorCode(err, abci.CodeType_InternalError)
 }
 
-func Unauthorized() TMError {
+func ErrDecoding() TMError {
-	return New(msgUnauthorized, abci.CodeType_Unauthorized)
+	return WithCode(errDecoding, abci.CodeType_EncodingError)
 }
 
-func MissingSignature() TMError {
+func IsDecodingErr(err error) bool {
-	return New(msgMissingSignature, abci.CodeType_Unauthorized)
+	return IsSameError(errDecoding, err)
 }
 
-func TooManySignatures() TMError {
+func ErrUnauthorized() TMError {
-	return New(msgTooManySignatures, abci.CodeType_Unauthorized)
+	return WithCode(errUnauthorized, abci.CodeType_Unauthorized)
 }
 
-func InvalidSignature() TMError {
+// IsUnauthorizedErr is generic helper for any unauthorized errors,
-	return New(msgInvalidSignature, abci.CodeType_Unauthorized)
+// also specific sub-types
+func IsUnauthorizedErr(err error) bool {
+	return HasErrorCode(err, abci.CodeType_Unauthorized)
 }
 
-func NoChain() TMError {
+func ErrMissingSignature() TMError {
-	return New(msgNoChain, abci.CodeType_Unauthorized)
+	return WithCode(errMissingSignature, abci.CodeType_Unauthorized)
 }
 
-func WrongChain(chain string) TMError {
+func IsMissingSignatureErr(err error) bool {
-	msg := fmt.Sprintf(msgWrongChain, chain)
+	return IsSameError(errMissingSignature, err)
-	return New(msg, abci.CodeType_Unauthorized)
+}
+
+func ErrTooManySignatures() TMError {
+	return WithCode(errTooManySignatures, abci.CodeType_Unauthorized)
+}
+
+func IsTooManySignaturesErr(err error) bool {
+	return IsSameError(errTooManySignatures, err)
+}
+
+func ErrInvalidSignature() TMError {
+	return WithCode(errInvalidSignature, abci.CodeType_Unauthorized)
+}
+
+func IsInvalidSignatureErr(err error) bool {
+	return IsSameError(errInvalidSignature, err)
+}
+
+func ErrNoChain() TMError {
+	return WithCode(errNoChain, abci.CodeType_Unauthorized)
+}
+
+func IsNoChainErr(err error) bool {
+	return IsSameError(errNoChain, err)
+}
+
+func ErrWrongChain(chain string) TMError {
+	msg := errors.Wrap(errWrongChain, chain)
+	return WithCode(msg, abci.CodeType_Unauthorized)
+}
+
+func IsWrongChainErr(err error) bool {
+	return IsSameError(errWrongChain, err)
 }
 
 func InvalidAddress() TMError {
-	return New(msgInvalidAddress, abci.CodeType_BaseInvalidInput)
+	return WithCode(errInvalidAddress, abci.CodeType_BaseInvalidInput)
 }
 
 func InvalidCoins() TMError {
-	return New(msgInvalidCoins, abci.CodeType_BaseInvalidInput)
+	return WithCode(errInvalidCoins, abci.CodeType_BaseInvalidInput)
 }
 
 func InvalidFormat() TMError {
-	return New(msgInvalidFormat, abci.CodeType_BaseInvalidInput)
+	return WithCode(errInvalidFormat, abci.CodeType_BaseInvalidInput)
 }
 
 func InvalidSequence() TMError {
-	return New(msgInvalidSequence, abci.CodeType_BaseInvalidInput)
+	return WithCode(errInvalidSequence, abci.CodeType_BaseInvalidInput)
 }
 
 func InsufficientFees() TMError {
-	return New(msgInsufficientFees, abci.CodeType_BaseInvalidInput)
+	return WithCode(errInsufficientFees, abci.CodeType_BaseInvalidInput)
 }
 
 func InsufficientFunds() TMError {
-	return New(msgInsufficientFunds, abci.CodeType_BaseInvalidInput)
+	return WithCode(errInsufficientFunds, abci.CodeType_BaseInvalidInput)
 }
 
 func NoInputs() TMError {
-	return New(msgNoInputs, abci.CodeType_BaseInvalidInput)
+	return WithCode(errNoInputs, abci.CodeType_BaseInvalidInput)
 }
 
 func NoOutputs() TMError {
-	return New(msgNoOutputs, abci.CodeType_BaseInvalidOutput)
+	return WithCode(errNoOutputs, abci.CodeType_BaseInvalidOutput)
 }
 
-func TooLarge() TMError {
+func ErrTooLarge() TMError {
-	return New(msgTooLarge, abci.CodeType_EncodingError)
+	return WithCode(errTooLarge, abci.CodeType_EncodingError)
+}
+
+func IsTooLargeErr(err error) bool {
+	return IsSameError(errTooLarge, err)
 }

errors/common_test.go

@@ -0,0 +1,74 @@
+package errors
+
+import (
+	"errors"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/tendermint/basecoin"
+)
+
+type DemoTx struct {
+	Age int
+}
+
+func (t DemoTx) Wrap() basecoin.Tx {
+	return basecoin.Tx{t}
+}
+
+func (t DemoTx) ValidateBasic() error {
+	return nil
+}
+
+func TestErrorMatches(t *testing.T) {
+	assert := assert.New(t)
+
+	cases := []struct {
+		pattern, err error
+		match        bool
+	}{
+		{errDecoding, ErrDecoding(), true},
+		{errUnauthorized, ErrUnauthorized(), true},
+		{errMissingSignature, ErrUnauthorized(), false},
+		{errMissingSignature, ErrMissingSignature(), true},
+		{errWrongChain, ErrWrongChain("hakz"), true},
+		{errUnknownTxType, ErrUnknownTxType(basecoin.Tx{}), true},
+		{errUnknownTxType, ErrUnknownTxType(DemoTx{5}.Wrap()), true},
+	}
+
+	for i, tc := range cases {
+		same := IsSameError(tc.pattern, tc.err)
+		assert.Equal(tc.match, same, "%d: %#v / %#v", i, tc.pattern, tc.err)
+	}
+}
+
+func TestChecks(t *testing.T) {
+	// TODO: make sure the Is and Err methods match
+	assert := assert.New(t)
+
+	cases := []struct {
+		err   error
+		check func(error) bool
+		match bool
+	}{
+		{ErrDecoding(), IsDecodingErr, true},
+		{ErrUnauthorized(), IsDecodingErr, false},
+		{ErrUnauthorized(), IsUnauthorizedErr, true},
+		{ErrInvalidSignature(), IsInvalidSignatureErr, true},
+		// unauthorized includes InvalidSignature, but not visa versa
+		{ErrInvalidSignature(), IsUnauthorizedErr, true},
+		{ErrUnauthorized(), IsInvalidSignatureErr, false},
+		// make sure WrongChain works properly
+		{ErrWrongChain("fooz"), IsUnauthorizedErr, true},
+		{ErrWrongChain("barz"), IsWrongChainErr, true},
+		// make sure lots of things match InternalErr, but not everything
+		{ErrInternal("bad db connection"), IsInternalErr, true},
+		{Wrap(errors.New("wrapped")), IsInternalErr, true},
+		{ErrUnauthorized(), IsInternalErr, false},
+	}
+
+	for i, tc := range cases {
+		match := tc.check(tc.err)
+		assert.Equal(tc.match, match, "%d", i)
+	}
+}

errors/main.go

@@ -19,6 +19,10 @@ type stackTracer interface {
 	StackTrace() errors.StackTrace
 }
 
+type causer interface {
+	Cause() error
+}
+
 type TMError interface {
 	stackTracer
 	ErrorCode() abci.CodeType
@@ -31,6 +35,11 @@ type tmerror struct {
 	msg  string
 }
 
+var (
+	_ causer = tmerror{}
+	_ error  = tmerror{}
+)
+
 func (t tmerror) ErrorCode() abci.CodeType {
 	return t.code
 }
@@ -39,6 +48,13 @@ func (t tmerror) Message() string {
 	return t.msg
 }
 
+func (t tmerror) Cause() error {
+	if c, ok := t.stackTracer.(causer); ok {
+		return c.Cause()
+	}
+	return t.stackTracer
+}
+
 // Format handles "%+v" to expose the full stack trace
 // concept from pkg/errors
 func (t tmerror) Format(s fmt.State, verb rune) {
@@ -102,3 +118,18 @@ func New(msg string, code abci.CodeType) TMError {
 		msg:         msg,
 	}
 }
+
+// IsSameError returns true if these errors have the same root cause.
+// pattern is the expected error type and should always be non-nil
+// err may be anything and returns true if it is a wrapped version of pattern
+func IsSameError(pattern error, err error) bool {
+	return err != nil && (errors.Cause(err) == errors.Cause(pattern))
+}
+
+// HasErrorCode checks if this error would return the named error code
+func HasErrorCode(err error, code abci.CodeType) bool {
+	if tm, ok := err.(TMError); ok {
+		return tm.ErrorCode() == code
+	}
+	return code == defaultErrCode
+}

errors/main_test.go

@@ -24,8 +24,8 @@ func TestCreateResult(t *testing.T) {
 		{New("nonce", abci.CodeType_BadNonce), "nonce", abci.CodeType_BadNonce},
 		{Wrap(stderr.New("wrap")), "wrap", defaultErrCode},
 		{WithCode(stderr.New("coded"), abci.CodeType_BaseInvalidInput), "coded", abci.CodeType_BaseInvalidInput},
-		{DecodingError(), msgDecoding, abci.CodeType_EncodingError},
+		{ErrDecoding(), errDecoding.Error(), abci.CodeType_EncodingError},
-		{Unauthorized(), msgUnauthorized, abci.CodeType_Unauthorized},
+		{ErrUnauthorized(), errUnauthorized.Error(), abci.CodeType_Unauthorized},
 	}
 
 	for idx, tc := range cases {