GOCBC-635: Add InvalidIndexError to LookupInResult

Change-Id: Ia88851e623a5054fb78a76ac4e063a3ae8dd2f24
Reviewed-on: http://review.couchbase.org/115693
Reviewed-by: Brett Lawson <brett19@gmail.com>
Tested-by: Charles Dixon <chvckd@gmail.com>

error.go

@@ -150,6 +150,22 @@ func (e serviceNotAvailableError) Error() string {
 	return e.message
 }
 
+// InvalidIndexError occurs when an invalid index is specified on a LookupInResult.
+type InvalidIndexError interface {
+	InvalidIndex() bool
+}
+
+type invalidIndexError struct {
+}
+
+func (err invalidIndexError) InvalidIndex() bool {
+	return true
+}
+
+func (err invalidIndexError) Error() string {
+	return "an invalid index was specified"
+}
+
 // ServiceNotAvailableError returns whether or not the error is a service not available error.
 func (e serviceNotAvailableError) ServiceNotAvailableError() bool {
 	return true
@@ -500,6 +516,17 @@ func IsSubdocPathExistsError(err error) bool {
 	return false
 }
 
+// IsInvalidIndexError verifies whether or not the cause for an error is due to an invalid index being specified on
+// a LookupInResult
+func IsInvalidIndexError(err error) bool {
+	switch errType := errors.Cause(err).(type) {
+	case InvalidIndexError:
+		return errType.InvalidIndex()
+	default:
+		return false
+	}
+}
+
 // Durability Specific Errors
 
 // IsDurabilityError verifies whether or not the cause for an error is due to a durability error.

results.go

@@ -257,14 +257,17 @@ func (pr *lookupInPartial) exists() bool {
 // ContentAt retrieves the value of the operation by its index. The index is the position of
 // the operation as it was added to the builder.
 func (lir *LookupInResult) ContentAt(idx int, valuePtr interface{}) error {
-	if idx > len(lir.contents) {
-		return invalidArgumentsError{message: "the supplied index was invalid"}
+	if idx >= len(lir.contents) {
+		return invalidIndexError{}
 	}
 	return lir.contents[idx].as(valuePtr, lir.serializer)
 }
 
 // Exists verifies that the item at idx exists.
 func (lir *LookupInResult) Exists(idx int) bool {
+	if idx >= len(lir.contents) {
+		return false
+	}
 	return lir.contents[idx].exists()
 }
 

results_test.go

@@ -2,7 +2,6 @@ package gocb
 
 import (
 	"encoding/json"
-	"errors"
 	"testing"
 
 	gocbcore "github.com/couchbase/gocbcore/v8"
@@ -197,9 +196,6 @@ func TestLookupInResultContentAt(t *testing.T) {
 			{
 				data: contents3,
 			},
-			{
-				err: errors.New("error"),
-			},
 		},
 		serializer: &DefaultJSONSerializer{},
 	}
@@ -248,8 +244,8 @@ func TestLookupInResultContentAt(t *testing.T) {
 
 	var shouldFail string
 	err = res.ContentAt(3, &shouldFail)
-	if err == nil {
-		t.Fatalf("ContentAt should have failed")
+	if !IsInvalidIndexError(err) {
+		t.Fatalf("ContentAt should have failed with InvalidIndexError, was %v", err)
 	}
 
 	if res.Exists(3) {