Merge pull request #2050 from travisturner/bsi-base-value

Default BSI base value to min, max, or 0 depending on the min/max range

field.go

@@ -143,6 +143,7 @@ func OptFieldTypeInt(min, max int64) FieldOption {
 		fo.Type = FieldTypeInt
 		fo.Min = min
 		fo.Max = max
+		fo.Base = bsiBase(min, max)
 		return nil
 	}
 }
@@ -499,7 +500,7 @@ func (f *Field) loadMeta() error {
 
 	// Initialize "base" to "min" when upgrading from v1 BSI format.
 	if pb.BitDepth == 0 {
-		pb.Base = pb.Min
+		pb.Base = bsiBase(pb.Min, pb.Max)
 		pb.BitDepth = uint64(bitDepthInt64(pb.Max - pb.Min))
 		if pb.BitDepth == 0 {
 			pb.BitDepth = 1
@@ -1501,6 +1502,18 @@ func isValidBSIGroupType(v string) bool {
 	}
 }
 
+// bsiBase is a helper function used to determine the default value
+// for base. Because base is not exposed as a field option argument,
+// it defaults to min, max, or 0 depending on the min/max range.
+func bsiBase(min, max int64) int64 {
+	if min > 0 {
+		return min
+	} else if max < 0 {
+		return max
+	}
+	return 0
+}
+
 // bsiGroup represents a group of range-encoded rows on a field.
 type bsiGroup struct {
 	Name     string `json:"name,omitempty"`

field_internal_test.go

@@ -412,3 +412,29 @@ func TestField_PersistAvailableShardsFootprint(t *testing.T) {
 	}
 
 }
+
+// Ensure that FieldOptions.Base defaults to the correct value.
+func TestBSIGroup_BaseDefaultValue(t *testing.T) {
+	for i, tt := range []struct {
+		min     int64
+		max     int64
+		expBase int64
+	}{
+		{100, 200, 100},
+		{-100, 100, 0},
+		{-200, -100, -100},
+	} {
+		fn := OptFieldTypeInt(tt.min, tt.max)
+
+		// Apply functional option.
+		fo := FieldOptions{}
+		err := fn(&fo)
+		if err != nil {
+			t.Fatalf("test %d, applying functional option: %s", i, err.Error())
+		}
+
+		if fo.Base != tt.expBase {
+			t.Fatalf("test %d, unexpected FieldOptions.Base value. expected: %d, but got: %d", i, tt.expBase, fo.Base)
+		}
+	}
+}