[New go generator] Implement declaring unions.

mojom/generators/go/translator/translator_test.go

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 package translator
 
 import (
         "sort"
         "testing"
 
@@ skipping 194 matching lines @@
         fileGraph.ResolvedTypes[typeKey] = &mojom_types.UserDefinedTypeStructType{mojomStruct}
         translator := NewTranslator(&fileGraph)
 
         typeRef := &mojom_types.TypeTypeReference{mojom_types.TypeReference{TypeKey: &typeKey}}
 
         info := translator.encodingInfo(typeRef)
 
         checkEq(t, true, info.IsPointer())
         checkEq(t, "SomeStruct", info.GoType())
 }
+
+func TestTranslateMojomUnion(t *testing.T) {
+        field1Name := "f_uint32"
+        field1 := mojom_types.UnionField{
+                DeclData: &mojom_types.DeclarationData{ShortName: &field1Name},
+                Type:     &mojom_types.TypeSimpleType{Value: mojom_types.SimpleType_Uint32},
+                Tag:      5}
+
+        field2Name := "f_uint16"
+        field2 := mojom_types.UnionField{
+                DeclData: &mojom_types.DeclarationData{ShortName: &field2Name},
+                Type:     &mojom_types.TypeSimpleType{Value: mojom_types.SimpleType_Uint16},
+                Tag:      6}
+
+        unionName := "foo"
+        union := mojom_types.MojomUnion{
+                DeclData: &mojom_types.DeclarationData{ShortName: &unionName},
+                Fields:   []mojom_types.UnionField{field1, field2},
+        }
+
+        graph := mojom_files.MojomFileGraph{}
+        typeKey := "typeKey"
+        graph.ResolvedTypes = map[string]mojom_types.UserDefinedType{
+                typeKey: &mojom_types.UserDefinedTypeUnionType{union},
+        }
+
+        translator := NewTranslator(&graph)
+
+        m := translator.translateMojomUnion(typeKey)
+
+        checkEq(t, "Foo", m.Name)
+        checkEq(t, "FUint32", m.Fields[0].Name)
+        checkEq(t, "uint32", m.Fields[0].Type)
+        checkEq(t, uint32(5), m.Fields[0].Tag)
+        checkEq(t, m, m.Fields[0].Union)
+        checkEq(t, "FUint16", m.Fields[1].Name)
+        checkEq(t, "uint16", m.Fields[1].Type)
+        checkEq(t, uint32(6), m.Fields[1].Tag)
+        checkEq(t, m, m.Fields[1].Union)
+}