Complete interface definitions for errors

errors.go

@@ -139,20 +139,28 @@ type errAlreadyExists struct{}
 
 func (errAlreadyExists) Error() string { return "already exists" }
 
+func (errAlreadyExists) AlreadyExists() {}
+
 func (e errAlreadyExists) WithMessage(msg string) error {
 	return customMessage{e, msg}
 }
 
+type alreadyExists interface {
+	AlreadyExists()
+}
+
 // IsAlreadyExists returns true if the error is due to an already existing
 // metadata item
 func IsAlreadyExists(err error) bool {
-	return errors.Is(err, ErrAlreadyExists)
+	return errors.Is(err, ErrAlreadyExists) || isInterface[alreadyExists](err)
 }
 
 type errPermissionDenied struct{}
 
 func (errPermissionDenied) Error() string { return "permission denied" }
 
+func (errPermissionDenied) Forbidden() {}
+
 func (e errPermissionDenied) WithMessage(msg string) error {
 	return customMessage{e, msg}
 }
@@ -172,28 +180,40 @@ type errResourceExhausted struct{}
 
 func (errResourceExhausted) Error() string { return "resource exhausted" }
 
+func (errResourceExhausted) ResourceExhausted() {}
+
 func (e errResourceExhausted) WithMessage(msg string) error {
 	return customMessage{e, msg}
 }
 
+type resourceExhausted interface {
+	ResourceExhausted()
+}
+
 // IsResourceExhausted returns true if the error is due to
 // a lack of resources or too many attempts.
 func IsResourceExhausted(err error) bool {
-	return errors.Is(err, errResourceExhausted{})
+	return errors.Is(err, errResourceExhausted{}) || isInterface[resourceExhausted](err)
 }
 
 type errFailedPrecondition struct{}
 
 func (e errFailedPrecondition) Error() string { return "failed precondition" }
 
+func (errFailedPrecondition) FailedPrecondition() {}
+
 func (e errFailedPrecondition) WithMessage(msg string) error {
 	return customMessage{e, msg}
 }
 
+type failedPrecondition interface {
+	FailedPrecondition()
+}
+
 // IsFailedPrecondition returns true if an operation could not proceed due to
 // the lack of a particular condition
 func IsFailedPrecondition(err error) bool {
-	return errors.Is(err, errFailedPrecondition{})
+	return errors.Is(err, errFailedPrecondition{}) || isInterface[failedPrecondition](err)
 }
 
 type errConflict struct{}
@@ -242,27 +262,39 @@ type errAborted struct{}
 
 func (errAborted) Error() string { return "aborted" }
 
+func (errAborted) Aborted() {}
+
 func (e errAborted) WithMessage(msg string) error {
 	return customMessage{e, msg}
 }
 
+type aborted interface {
+	Aborted()
+}
+
 // IsAborted returns true if an operation was aborted.
 func IsAborted(err error) bool {
-	return errors.Is(err, errAborted{})
+	return errors.Is(err, errAborted{}) || isInterface[aborted](err)
 }
 
 type errOutOfRange struct{}
 
 func (errOutOfRange) Error() string { return "out of range" }
 
+func (errOutOfRange) OutOfRange() {}
+
 func (e errOutOfRange) WithMessage(msg string) error {
 	return customMessage{e, msg}
 }
 
+type outOfRange interface {
+	OutOfRange()
+}
+
 // IsOutOfRange returns true if an operation could not proceed due
 // to data being out of the expected range.
 func IsOutOfRange(err error) bool {
-	return errors.Is(err, errOutOfRange{})
+	return errors.Is(err, errOutOfRange{}) || isInterface[outOfRange](err)
 }
 
 type errNotImplemented struct{}

errors_test.go

@@ -19,6 +19,7 @@ package errdefs
 import (
 	"context"
 	"errors"
+	"fmt"
 	"reflect"
 	"testing"
 )
@@ -158,6 +159,39 @@ func TestWithMessage(t *testing.T) {
 	}
 }
 
+func TestInterfaceMatch(t *testing.T) {
+	testCases := []struct {
+		err   error
+		check func(error) bool
+	}{
+		{ErrUnknown, isInterface[unknown]},
+		{ErrInvalidArgument, isInterface[invalidParameter]},
+		{ErrNotFound, isInterface[notFound]},
+		{ErrAlreadyExists, isInterface[alreadyExists]},
+		{ErrPermissionDenied, isInterface[forbidden]},
+		{ErrResourceExhausted, isInterface[resourceExhausted]},
+		{ErrFailedPrecondition, isInterface[failedPrecondition]},
+		{ErrConflict, isInterface[conflict]},
+		{ErrNotModified, isInterface[notModified]},
+		{ErrAborted, isInterface[aborted]},
+		{ErrOutOfRange, isInterface[outOfRange]},
+		{ErrNotImplemented, isInterface[notImplemented]},
+		{ErrInternal, isInterface[system]},
+		{ErrUnavailable, isInterface[unavailable]},
+		{ErrDataLoss, isInterface[dataLoss]},
+		{ErrUnauthenticated, isInterface[unauthorized]},
+	}
+
+	for _, tc := range testCases {
+		tc := tc
+		t.Run(fmt.Sprintf("%T", tc.err), func(t *testing.T) {
+			if !tc.check(tc.err) {
+				t.Fatal("Error does not match interface")
+			}
+		})
+	}
+}
+
 type customInvalidArgument struct{}
 
 func (*customInvalidArgument) Error() string {

resolve.go

@@ -74,17 +74,22 @@ func firstError(err error) error {
 			return ErrInvalidArgument
 		case notFound:
 			return ErrNotFound
-		// Skip ErrAlreadyExists, no interface defined
+		case alreadyExists:
+			return ErrAlreadyExists
 		case forbidden:
 			return ErrPermissionDenied
-		// Skip ErrResourceExhasuted, no interface defined
-		// Skip ErrFailedPrecondition, no interface defined
+		case resourceExhausted:
+			return ErrResourceExhausted
+		case failedPrecondition:
+			return ErrFailedPrecondition
 		case conflict:
 			return ErrConflict
 		case notModified:
 			return ErrNotModified
-		// Skip ErrAborted, no interface defined
-		// Skip ErrOutOfRange, no interface defined
+		case aborted:
+			return ErrAborted
+		case errOutOfRange:
+			return ErrOutOfRange
 		case notImplemented:
 			return ErrNotImplemented
 		case system: