Add additional benchmarks for "updates"

We currently were mostly benchmarking creation, apply but not updates,
nor any updates across versions. These new tests show that updates are
extremely expensive for objects that have big "atomic" values because
the comparison is pretty slow.

Author: Antoine Pelisse

merge/real_test.go

@@ -17,7 +17,6 @@ limitations under the License.
 package merge_test
 
 import (
-	"fmt"
 	"io/ioutil"
 	"path/filepath"
 	"strings"
@@ -76,33 +75,74 @@ func BenchmarkOperations(b *testing.B) {
 	}
 
 	for _, bench := range benches {
-
 		b.Run(lastPart(bench.typename), func(b *testing.B) {
-			ops := []Operation{
-				Update{
-					Manager:    "controller",
-					APIVersion: "v1",
-					Object:     bench.obj,
+			tests := []struct {
+				name string
+				ops  []Operation
+			}{
+				{
+					name: "Create",
+					ops: []Operation{
+						Update{
+							Manager:    "controller",
+							APIVersion: "v1",
+							Object:     bench.obj,
+						},
+					},
+				},
+				{
+					name: "Apply",
+					ops: []Operation{
+						Apply{
+							Manager:    "controller",
+							APIVersion: "v1",
+							Object:     bench.obj,
+						},
+					},
+				},
+				{
+					name: "Update",
+					ops: []Operation{
+						Update{
+							Manager:    "controller",
+							APIVersion: "v1",
+							Object:     bench.obj,
+						},
+						Update{
+							Manager:    "other-controller",
+							APIVersion: "v1",
+							Object:     bench.obj,
+						},
+					},
 				},
-				Apply{
-					Manager:    "controller",
-					APIVersion: "v1",
-					Object:     bench.obj,
+				{
+					name: "UpdateVersion",
+					ops: []Operation{
+						Update{
+							Manager:    "controller",
+							APIVersion: "v1",
+							Object:     bench.obj,
+						},
+						Update{
+							Manager:    "other-controller",
+							APIVersion: "v2",
+							Object:     bench.obj,
+						},
+					},
 				},
 			}
-			for _, op := range ops {
-				b.Run(lastPart(fmt.Sprintf("%T", op)), func(b *testing.B) {
-					test := TestCase{
-						Ops: []Operation{op},
-					}
-
+			for _, test := range tests {
+				b.Run(test.name, func(b *testing.B) {
 					pt := parser.Type(bench.typename)
-					test.PreprocessOperations(pt)
+					tc := TestCase{
+						Ops: test.ops,
+					}
+					tc.PreprocessOperations(pt)
 
 					b.ReportAllocs()
 					b.ResetTimer()
 					for n := 0; n < b.N; n++ {
-						if err := test.Bench(pt); err != nil {
+						if err := tc.Bench(pt); err != nil {
 							b.Fatal(err)
 						}
 					}