Replace errors.Cause() with errors.Is()

Dependencies may be switching to use the new `%w` formatting
option to wrap errors; switching to use `errors.Is()` makes
sure that we are still able to unwrap the error and detect the
underlying cause.

Signed-off-by: Sebastiaan van Stijn <github@gone.nl>

errdefs/errors.go

@@ -51,43 +51,43 @@ var (
 
 // IsInvalidArgument returns true if the error is due to an invalid argument
 func IsInvalidArgument(err error) bool {
-	return errors.Cause(err) == ErrInvalidArgument
+	return errors.Is(err, ErrInvalidArgument)
 }
 
 // IsNotFound returns true if the error is due to a missing object
 func IsNotFound(err error) bool {
-	return errors.Cause(err) == ErrNotFound
+	return errors.Is(err, ErrNotFound)
 }
 
 // IsAlreadyExists returns true if the error is due to an already existing
 // metadata item
 func IsAlreadyExists(err error) bool {
-	return errors.Cause(err) == ErrAlreadyExists
+	return errors.Is(err, ErrAlreadyExists)
 }
 
 // IsFailedPrecondition returns true if an operation could not proceed to the
 // lack of a particular condition
 func IsFailedPrecondition(err error) bool {
-	return errors.Cause(err) == ErrFailedPrecondition
+	return errors.Is(err, ErrFailedPrecondition)
 }
 
 // IsUnavailable returns true if the error is due to a resource being unavailable
 func IsUnavailable(err error) bool {
-	return errors.Cause(err) == ErrUnavailable
+	return errors.Is(err, ErrUnavailable)
 }
 
 // IsNotImplemented returns true if the error is due to not being implemented
 func IsNotImplemented(err error) bool {
-	return errors.Cause(err) == ErrNotImplemented
+	return errors.Is(err, ErrNotImplemented)
 }
 
 // IsCanceled returns true if the error is due to `context.Canceled`.
 func IsCanceled(err error) bool {
-	return errors.Cause(err) == context.Canceled
+	return errors.Is(err, context.Canceled)
 }
 
 // IsDeadlineExceeded returns true if the error is due to
 // `context.DeadlineExceeded`.
 func IsDeadlineExceeded(err error) bool {
-	return errors.Cause(err) == context.DeadlineExceeded
+	return errors.Is(err, context.DeadlineExceeded)
 }

errdefs/grpc_test.go

@@ -88,6 +88,9 @@ func TestGRPCRoundTrip(t *testing.T) {
 			if errors.Cause(ferr) != testcase.cause {
 				t.Fatalf("unexpected cause: %v != %v", errors.Cause(ferr), testcase.cause)
 			}
+			if !errors.Is(ferr, testcase.cause) {
+				t.Fatalf("unexpected cause: !errors.Is(%v, %v)", ferr, testcase.cause)
+			}
 
 			expected := testcase.str
 			if expected == "" {