parity: add LCOW document permutation tests

test/parity/vm/doc.go

@@ -1,7 +1,13 @@
 //go:build windows
 
-// Package vmparity validates that the v2 modular VM document builders produce
-// HCS ComputeSystem documents equivalent to the legacy shim pipelines.
+// Package vmparity validates that the v2 VM document builders produce HCS
+// ComputeSystem documents equivalent to the legacy shim pipelines.
 //
-// Currently covers LCOW; WCOW parity will be added in a future PR.
+// Currently covers LCOW parity between:
+//   - Legacy: OCI spec → oci.UpdateSpecFromOptions → oci.ProcessAnnotations →
+//     oci.SpecToUVMCreateOpts → uvm.MakeLCOWDoc → *hcsschema.ComputeSystem
+//   - V2: vm.Spec + runhcsopts.Options → lcow.BuildSandboxConfig →
+//     *hcsschema.ComputeSystem + *SandboxOptions
+//
+// WCOW parity will be added in a future PR.
 package vmparity

test/parity/vm/hcs_lcow_document_creator_test.go

@@ -8,8 +8,10 @@ import (
 	"fmt"
 	"os"
 	"path/filepath"
+	"strings"
 	"testing"
 
+	"github.com/google/go-cmp/cmp"
 	"github.com/opencontainers/runtime-spec/specs-go"
 
 	runhcsopts "github.com/Microsoft/hcsshim/cmd/containerd-shim-runhcs-v1/options"
@@ -111,3 +113,45 @@ func jsonToString(v interface{}) string {
 	}
 	return string(b)
 }
+
+// normalizeKernelCmdLine trims leading/trailing whitespace from the kernel
+// command line in the document. The legacy builder has a minor quirk that
+// produces a leading space for initrd+KernelDirect boot. The v2 builder
+// does not. Since HCS trims whitespace from kernel args, this difference
+// is harmless and we normalize it away.
+func normalizeKernelCmdLine(doc *hcsschema.ComputeSystem) {
+	if doc == nil || doc.VirtualMachine == nil || doc.VirtualMachine.Chipset == nil {
+		return
+	}
+	if kd := doc.VirtualMachine.Chipset.LinuxKernelDirect; kd != nil {
+		kd.KernelCmdLine = strings.TrimSpace(kd.KernelCmdLine)
+	}
+	if uefi := doc.VirtualMachine.Chipset.Uefi; uefi != nil && uefi.BootThis != nil {
+		uefi.BootThis.OptionalData = strings.TrimSpace(uefi.BootThis.OptionalData)
+	}
+}
+
+// deepCopyDoc returns a deep copy of a ComputeSystem via JSON round-trip.
+func deepCopyDoc(doc *hcsschema.ComputeSystem) *hcsschema.ComputeSystem {
+	b, err := json.Marshal(doc)
+	if err != nil {
+		panic(fmt.Sprintf("failed to marshal ComputeSystem for deep copy: %v", err))
+	}
+	var copy hcsschema.ComputeSystem
+	if err := json.Unmarshal(b, &copy); err != nil {
+		panic(fmt.Sprintf("failed to unmarshal ComputeSystem for deep copy: %v", err))
+	}
+	return &copy
+}
+
+// isOnlyKernelCmdLineWhitespaceDiff returns true if the only difference between
+// two documents is leading/trailing whitespace in the kernel command line.
+// This is a known legacy quirk where initrd+KernelDirect boot produces a
+// leading space that v2 correctly omits.
+func isOnlyKernelCmdLineWhitespaceDiff(legacy, v2 *hcsschema.ComputeSystem) bool {
+	legacyCopy := deepCopyDoc(legacy)
+	v2Copy := deepCopyDoc(v2)
+	normalizeKernelCmdLine(legacyCopy)
+	normalizeKernelCmdLine(v2Copy)
+	return cmp.Diff(legacyCopy, v2Copy) == ""
+}