add UT

Author: wk989898

record.go

@@ -14,7 +14,7 @@ import (
 	"sync/atomic"
 )
 
-var stringNull int32
+var stringNull int32 = 1
 
 func makeRecordCodec(st map[string]*Codec, enclosingNamespace string, schemaMap map[string]interface{}, cb *codecBuilder) (*Codec, error) {
 	// NOTE: To support recursive data types, create the codec and register it

record_test.go

@@ -396,6 +396,12 @@ func TestRecordFieldDefaultValue(t *testing.T) {
 func TestRecordFieldUnionDefaultValue(t *testing.T) {
 	testSchemaValid(t, `{"type":"record","name":"r1","fields":[{"name":"f1","type":["int","null"],"default":13}]}`)
 	testSchemaValid(t, `{"type":"record","name":"r1","fields":[{"name":"f1","type":["null","int"],"default":null}]}`)
+	testSchemaValid(t, `{"type":"record","name":"r1","fields":[{"name":"f1","type":["null","int"],"default":"null"}]}`)
+	DisableStringNull()
+	testSchemaInvalid(t, `{"type":"record","name":"r1","fields":[{"name":"f1","type":["null","int"],"default":"null"}]}`,
+		"default value ought to encode using field schema")
+	EnableStringNull()
+	testSchemaValid(t, `{"type":"record","name":"r1","fields":[{"name":"f1","type":["null","int"],"default":"null"}]}`)
 }
 
 func TestRecordFieldUnionInvalidDefaultValue(t *testing.T) {