Mojom frontend: Correctly handle empty structs in computeVersionInfo()

mojom/mojom_parser/serialization/serialization_test.go

 // Copyright 2015 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 serialization
 
 import (
         "bytes"
         "compress/gzip"
         "encoding/base64"
@@ skipping 1137 matching lines @@
                 }
         }
 }
 
 // TestWithComputedData is similar to the previous test except that it sets
 // emitComputedPackingData = true.
 func TestWithComputedData(t *testing.T) {
         test := singleFileTest{}
 
         ////////////////////////////////////////////////////////////
+        // Test Case: Empty struct
+        ////////////////////////////////////////////////////////////
+        {
+                contents := `
+        struct Foo{
+        };`
+
+                test.addTestCase("", contents)
+
+                test.expectedFile().DeclaredMojomObjects.Structs = &[]string{"TYPE_KEY:Foo"}
+
+                test.expectedGraph().ResolvedTypes["TYPE_KEY:Foo"] = &mojom_types.UserDefinedTypeStructType{mojom_types.MojomStruct{
+                        DeclData: test.newDeclData("Foo", "Foo"),
+                        Fields:   []mojom_types.StructField{},
+                        VersionInfo: &[]mojom_types.StructVersion{
+                                mojom_types.StructVersion{
+                                        VersionNumber: 0,
+                                        NumFields:     0,
+                                        NumBytes:      8,
+                                },
+                        },
+                }}
+
+                test.endTestCase()
+        }
+
+        ////////////////////////////////////////////////////////////
         // Test Case: Test struct field min versions: 1,2
         ////////////////////////////////////////////////////////////
         {
                 contents := `
         struct Foo{
           int32 x;
           int32 y;
 
           [MinVersion = 1]
           array<int32>? z;
@@ skipping 2017 matching lines @@
                         }
                         return fmt.Errorf("*****\nexpected=\n*****\n%q\n*****\nactual=\n*****\n%q\n*****\n"+
                                 "match failed at position %d: expected=\n*****\n%q\n******\nactual=\n*****\n%q\n******\n",
                                 expectedString, actualString, diffPos, mismatchExpected, mismatchActual)
                 } else {
                         return fmt.Errorf("expected != actual but the two printed equal.")
                 }
         }
         return nil
 }