move error conversion from session to qerr.ToQuicError

qerr/quic_error.go

@@ -2,6 +2,8 @@ package qerr
 
 import (
 	"fmt"
+
+	"github.com/lucas-clemente/quic-go/utils"
 )
 
 // ErrorCode can be used as a normal error without reason.
@@ -28,3 +30,16 @@ func Error(errorCode ErrorCode, errorMessage string) *QuicError {
 func (e *QuicError) Error() string {
 	return fmt.Sprintf("%s: %s", e.ErrorCode.String(), e.ErrorMessage)
 }
+
+// ToQuicError converts an arbitrary error to a QuicError. It leaves QuicErrors
+// unchanged, and properly handles `ErrorCode`s.
+func ToQuicError(err error) *QuicError {
+	switch e := err.(type) {
+	case *QuicError:
+		return e
+	case ErrorCode:
+		return Error(e, "")
+	}
+	utils.Errorf("BUG: Unknown error encountered: %#v", err)
+	return Error(InternalError, "")
+}

qerr/quic_error_test.go

@@ -1,6 +1,8 @@
 package qerr_test
 
 import (
+	"io"
+
 	"github.com/lucas-clemente/quic-go/qerr"
 
 	. "github.com/onsi/ginkgo"
@@ -8,8 +10,33 @@ import (
 )
 
 var _ = Describe("Quic error", func() {
-	It("has a string representation", func() {
-		err := qerr.Error(qerr.InternalError, "foobar")
-		Expect(err.Error()).To(Equal("InternalError: foobar"))
+	Context("QuicError", func() {
+		It("has a string representation", func() {
+			err := qerr.Error(qerr.DecryptionFailure, "foobar")
+			Expect(err.Error()).To(Equal("DecryptionFailure: foobar"))
+		})
+	})
+
+	Context("ErrorCode", func() {
+		It("works as error", func() {
+			var err error = qerr.DecryptionFailure
+			Expect(err).To(MatchError("DecryptionFailure"))
+		})
+	})
+
+	Context("ToQuicError", func() {
+		It("leaves QuicError unchanged", func() {
+			err := qerr.Error(qerr.DecryptionFailure, "foo")
+			Expect(qerr.ToQuicError(err)).To(Equal(err))
+		})
+
+		It("wraps ErrorCode properly", func() {
+			var err error = qerr.DecryptionFailure
+			Expect(qerr.ToQuicError(err)).To(Equal(qerr.Error(qerr.DecryptionFailure, "")))
+		})
+
+		It("changes default errors to InternalError", func() {
+			Expect(qerr.ToQuicError(io.EOF)).To(Equal(qerr.Error(qerr.InternalError, "")))
+		})
 	})
 })