test(s3/lifecycle): final unit-test cleanup before integration suite (#9414)

* test(s3/lifecycle): final unit-test cleanup before integration suite

Closes the residual coverage gaps in the lifecycle packages so the
next track (Layer 3 integration tests) starts from a clean baseline.
Big coverage lifts: lifecycletest 88.7→100.0, engine 81.7→95.1,
s3lifecycle 87.8→95.0, dispatcher 60.3→67.6, router 86.1→88.8,
bootstrap 90.7→92.6. Remaining sub-100% surfaces (reader.Run,
Pipeline.Run, scheduler.Run, multi-step bootstrap orchestration)
need a live filer and belong with the integration suite.

router/helpers_test.go (formerly #9409, now stale on master because
9410-9413 absorbed adjacent surface): direct tests for the pure
helpers Route exercises indirectly — successorModTimeFromContainer
(missing/empty/non-numeric/non-positive/positive round-trip),
logicalKeyFromVersionPath (extracts logical, rejects non-.versions
parent / root-level / no-slashes / bare container), isVersionsContainerKey
(table over container forms), isVersionFolderPath (table over child
forms), isDeleteMarkerEntry (only literal "true" matches),
extractTags (nil/empty, AmzObjectTagging-prefixed only, no-tag
returns nil), hasActiveEventDrivenAction (matches only active+
event-driven, scan-only rejected, unknown skipped). Plus engine
Snapshot accessors: BucketVersioned (compiled flag, unknown bucket
false), BucketActionKeys (full list, unknown nil), Action (unknown
nil), AllActions (every kind), SnapshotID (strictly monotonic).

s3lifecycle/final_cleanup_test.go: ActionKind.String default branch
(unspecified + future-unknown render "unspecified" rather than
empty); HashExtended direct from the lifecycle package (covers it
in this package's coverage report, not just the s3api one) including
nil/empty produces no bytes and identical content hashes the same.

bootstrap/has_prefix_test.go: thin wrapper around strings.HasPrefix
exported by the package; trivial but at 0% pre-fix.

lifecycletest/eventbuilder_old_entry_test.go: pins the OldEntry
fall-through path on Delete events for WithModTime / WithTtlSec /
WithVersionID / WithExtended / WithChunks (existing tests cover
Create events that hit NewEntry only). Adds WithBootstrapVersion
across all three event shapes. Defensive: every With* option is a
no-op on a degenerate event with neither entry populated.

* test(s3/lifecycle): address coderabbit nitpicks on final cleanup

- eventbuilder empty-event test now exercises WithBootstrapVersion
  too, with an honest claim about its scope: it targets the event
  itself (not an entry), so it sets BootstrapVersion regardless of
  whether NewEntry/OldEntry are populated. Renamed the test from
  AllAreNoOpsOnEmptyEvent to NoPanicOnEmptyEvent since the original
  name overstated the contract.
- HashExtended stability check uses a 3-key map with different
  literal orders so the helper's sort path actually does work; a
  single-key check can't catch an iteration-order regression.
- HasPrefix test refactored to table-driven so adding a new edge
  case is one row instead of two assertion lines.
This commit is contained in:
Chris Lu
2026-05-09 22:32:49 -07:00
committed by GitHub
parent b740e22e63
commit 2840980c7d
4 changed files with 518 additions and 0 deletions
@@ -0,0 +1,33 @@
package bootstrap
import (
"testing"
"github.com/stretchr/testify/assert"
)
// HasPrefix is a thin wrapper around strings.HasPrefix exported by the
// bootstrap package so call sites can avoid pulling strings just to do
// a prefix check. Trivial but at 0% coverage — pin it.
func TestHasPrefix(t *testing.T) {
cases := []struct {
name string
path string
prefix string
want bool
}{
{"matching prefix", "logs/2026/01/01", "logs/", true},
{"exact match", "logs/", "logs/", true},
{"non-matching prefix", "metrics/x", "logs/", false},
{"shorter than prefix", "logs", "logs/", false},
{"empty prefix matches all", "anything", "", true},
{"both empty", "", "", true},
{"empty input non-empty prefix", "", "x", false},
}
for _, c := range cases {
t.Run(c.name, func(t *testing.T) {
assert.Equal(t, c.want, HasPrefix(c.path, c.prefix))
})
}
}
@@ -0,0 +1,48 @@
package s3lifecycle
import (
"testing"
"github.com/stretchr/testify/assert"
)
// Final unit-test cleanup ahead of the integration suite. Pins the
// remaining 0%-and-default-branch helpers in the s3lifecycle package
// and the lifecycletest builder so a regression doesn't slip in
// during the integration work that follows.
func TestActionKind_StringUnspecifiedDefault(t *testing.T) {
// String's default branch (covers ActionKindUnspecified and any
// future enum value not listed) must render "unspecified" rather
// than empty or panic. Operators read this via the metrics labels
// (see S3LifecycleDispatchCounter "kind").
assert.Equal(t, "unspecified", ActionKindUnspecified.String())
assert.Equal(t, "unspecified", ActionKind(99).String())
}
func TestHashExtended_DirectFromLifecyclePackage(t *testing.T) {
// HashExtended is exercised from the s3api package's identity
// tests; pin it here so the s3lifecycle package's own coverage
// reflects the call. A nil/empty map produces no bytes, so the
// CAS witness collapses to "no Extended" rather than a synthetic
// hash that would mismatch on the server.
assert.Empty(t, HashExtended(nil))
assert.Empty(t, HashExtended(map[string][]byte{}))
got := HashExtended(map[string][]byte{"a": []byte("1")})
assert.NotEmpty(t, got)
// Same content, different literal/insertion order across multiple
// keys: hash must be stable. A single-key check can't catch an
// iteration-order regression — multiple keys force the helper's
// sort path to actually do work.
first := HashExtended(map[string][]byte{
"a": []byte("1"),
"b": []byte("2"),
"c": []byte("3"),
})
second := HashExtended(map[string][]byte{
"c": []byte("3"),
"a": []byte("1"),
"b": []byte("2"),
})
assert.Equal(t, first, second, "hash must be insensitive to map iteration order")
}
@@ -0,0 +1,102 @@
package lifecycletest
import (
"testing"
"time"
"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
"github.com/seaweedfs/seaweedfs/weed/s3api/s3_constants"
"github.com/seaweedfs/seaweedfs/weed/s3api/s3lifecycle/reader"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
// Coverage gap-fillers for the With* options' OldEntry-only branches
// (NewEntry==nil, OldEntry populated — i.e. Delete events). The
// existing eventbuilder_test.go covers Create events; these tests
// exercise the alternate fall-through path on each option.
func TestEventOption_WithModTime_AppliesToOldEntryOnDelete(t *testing.T) {
t0 := time.Unix(1700000000, 0)
override := time.Unix(1699000000, 250)
e := NewDelete("bk", "k", t0, WithModTime(override))
require.Nil(t, e.NewEntry)
require.NotNil(t, e.OldEntry)
assert.Equal(t, override.Unix(), e.OldEntry.Attributes.Mtime)
assert.Equal(t, int32(250), e.OldEntry.Attributes.MtimeNs)
}
func TestEventOption_WithTtlSec_AppliesToOldEntryOnDelete(t *testing.T) {
e := NewDelete("bk", "k", time.Unix(0, 0), WithTtlSec(7200))
require.NotNil(t, e.OldEntry)
assert.Equal(t, int32(7200), e.OldEntry.Attributes.TtlSec)
}
func TestEventOption_WithVersionID_AppliesToOldEntryOnDelete(t *testing.T) {
// VersionID-on-delete: the bootstrapper synthesizes deletes for
// noncurrent-version sweeps and needs the version-id stamp.
e := NewDelete("bk", "k", time.Unix(0, 0), WithVersionID("v_old"))
require.NotNil(t, e.OldEntry)
require.NotNil(t, e.OldEntry.Extended)
assert.Equal(t, []byte("v_old"), e.OldEntry.Extended[s3_constants.ExtVersionIdKey])
}
func TestEventOption_WithExtended_AppliesToOldEntryOnDelete(t *testing.T) {
e := NewDelete("bk", "k", time.Unix(0, 0), WithExtended("Custom-Tag", []byte("v")))
require.NotNil(t, e.OldEntry)
require.NotNil(t, e.OldEntry.Extended)
assert.Equal(t, []byte("v"), e.OldEntry.Extended["Custom-Tag"])
}
func TestEventOption_WithChunks_AppliesToOldEntryOnDelete(t *testing.T) {
c := &filer_pb.FileChunk{FileId: "1,old"}
e := NewDelete("bk", "k", time.Unix(0, 0), WithChunks(c))
require.NotNil(t, e.OldEntry)
require.Len(t, e.OldEntry.Chunks, 1)
assert.Equal(t, "1,old", e.OldEntry.Chunks[0].FileId)
}
func TestEventOption_WithBootstrapVersion(t *testing.T) {
// WithBootstrapVersion attaches a BootstrapVersion to the event;
// the bootstrap walker uses this for per-version state the live
// meta-log doesn't carry. Pin both create and delete shapes.
bv := &reader.BootstrapVersion{
LogicalKey: "obj.txt",
VersionID: "v_aaa",
IsLatest: true,
IsDeleteMarker: false,
NumVersions: 3,
NoncurrentIndex: 2,
}
create := NewCreate("bk", "obj.txt", time.Unix(0, 0), WithBootstrapVersion(bv))
require.Same(t, bv, create.BootstrapVersion)
del := NewDelete("bk", "obj.txt", time.Unix(0, 0), WithBootstrapVersion(bv))
require.Same(t, bv, del.BootstrapVersion)
update := NewUpdate("bk", "obj.txt", time.Unix(0, 0), WithBootstrapVersion(bv))
require.Same(t, bv, update.BootstrapVersion)
}
func TestEventOption_NoPanicOnEmptyEvent(t *testing.T) {
// Defense: an event with neither NewEntry nor OldEntry must not
// panic on any With* option, even though no constructor produces
// this shape today. Entry-targeting options fall through silently
// (NewEntry/OldEntry stay nil); WithBootstrapVersion targets the
// event itself, not an entry, so it does set BootstrapVersion —
// included here for panic safety.
e := &reader.Event{}
WithModTime(time.Unix(1, 0))(e)
WithTtlSec(60)(e)
WithVersionID("v")(e)
WithExtended("k", []byte("v"))(e)
WithChunks(&filer_pb.FileChunk{FileId: "x"})(e)
WithSize(1024)(e)
bv := &reader.BootstrapVersion{VersionID: "v"}
WithBootstrapVersion(bv)(e)
assert.Nil(t, e.NewEntry, "entry-targeting options must not allocate NewEntry")
assert.Nil(t, e.OldEntry, "entry-targeting options must not allocate OldEntry")
assert.Same(t, bv, e.BootstrapVersion, "WithBootstrapVersion sets the field regardless of entry state")
}
@@ -0,0 +1,335 @@
package router
import (
"testing"
"time"
"github.com/seaweedfs/seaweedfs/weed/pb/filer_pb"
"github.com/seaweedfs/seaweedfs/weed/s3api/s3_constants"
"github.com/seaweedfs/seaweedfs/weed/s3api/s3lifecycle"
"github.com/seaweedfs/seaweedfs/weed/s3api/s3lifecycle/engine"
"github.com/stretchr/testify/assert"
"github.com/stretchr/testify/require"
)
// Direct coverage for the pure helpers in router.go that the larger
// Route* tests exercise indirectly. Pinning each one separately catches
// regressions before they manifest as a broader Route failure that's
// harder to diagnose.
// ---------- successorModTimeFromContainer ----------
func TestSuccessorModTimeFromContainer_MissingExtReturnsZero(t *testing.T) {
assert.True(t, successorModTimeFromContainer(&filer_pb.Entry{}).IsZero())
assert.True(t, successorModTimeFromContainer(&filer_pb.Entry{
Extended: map[string][]byte{},
}).IsZero())
}
func TestSuccessorModTimeFromContainer_EmptyValueReturnsZero(t *testing.T) {
got := successorModTimeFromContainer(&filer_pb.Entry{
Extended: map[string][]byte{s3_constants.ExtLatestVersionMtimeKey: nil},
})
assert.True(t, got.IsZero())
}
func TestSuccessorModTimeFromContainer_NonNumericReturnsZero(t *testing.T) {
// A malformed value is the writer's bug; the helper must not
// propagate a parse error or surface a nonsense time.
got := successorModTimeFromContainer(&filer_pb.Entry{
Extended: map[string][]byte{s3_constants.ExtLatestVersionMtimeKey: []byte("not-a-number")},
})
assert.True(t, got.IsZero())
}
func TestSuccessorModTimeFromContainer_NonPositiveReturnsZero(t *testing.T) {
// The container ext stores Unix seconds; <=0 means "not set" so
// the helper falls back to zero rather than emitting 1970-01-01.
for _, raw := range []string{"0", "-1", "-1000"} {
t.Run(raw, func(t *testing.T) {
got := successorModTimeFromContainer(&filer_pb.Entry{
Extended: map[string][]byte{s3_constants.ExtLatestVersionMtimeKey: []byte(raw)},
})
assert.True(t, got.IsZero(), "value %q must produce zero time", raw)
})
}
}
func TestSuccessorModTimeFromContainer_PositiveSecondsRoundTrip(t *testing.T) {
got := successorModTimeFromContainer(&filer_pb.Entry{
Extended: map[string][]byte{s3_constants.ExtLatestVersionMtimeKey: []byte("1700000000")},
})
assert.Equal(t, time.Unix(1700000000, 0).UTC(), got.UTC())
}
// ---------- logicalKeyFromVersionPath ----------
func TestLogicalKeyFromVersionPath_ExtractsLogicalKey(t *testing.T) {
logical, ok := logicalKeyFromVersionPath("a/b/c.versions/v_abc")
require.True(t, ok)
assert.Equal(t, "a/b/c", logical)
}
func TestLogicalKeyFromVersionPath_RejectsPathWithoutVersionsParent(t *testing.T) {
// The parent of the version file must end with .versions; otherwise
// it's not a version path.
_, ok := logicalKeyFromVersionPath("a/b/c/v_abc")
assert.False(t, ok)
}
func TestLogicalKeyFromVersionPath_RejectsRootLevelPath(t *testing.T) {
// LastIndex returning 0 means the only "/" is at index 0, which
// would yield an empty parent — not a real version path.
_, ok := logicalKeyFromVersionPath("/v_abc")
assert.False(t, ok)
}
func TestLogicalKeyFromVersionPath_RejectsNoSlashes(t *testing.T) {
_, ok := logicalKeyFromVersionPath("v_abc")
assert.False(t, ok)
_, ok = logicalKeyFromVersionPath("")
assert.False(t, ok)
}
func TestLogicalKeyFromVersionPath_RejectsBareVersionsContainer(t *testing.T) {
// A path that's only the .versions container has no version-file
// child to extract a logical key from.
_, ok := logicalKeyFromVersionPath(s3_constants.VersionsFolder + "/v_x")
assert.False(t, ok, "logical key cannot be empty after trim")
}
// ---------- isVersionsContainerKey ----------
func TestIsVersionsContainerKey(t *testing.T) {
cases := []struct {
key string
want bool
}{
{"obj" + s3_constants.VersionsFolder, true},
{"a/b/obj" + s3_constants.VersionsFolder, true},
// Bucket-root .versions is rejected explicitly: it has no
// logical object key, so the router can't process it.
{s3_constants.VersionsFolder, false},
{"obj.versions/v_x", false}, // the version file inside, not the container
{"obj", false},
{"", false},
}
for _, c := range cases {
t.Run(c.key, func(t *testing.T) {
assert.Equal(t, c.want, isVersionsContainerKey(c.key))
})
}
}
// ---------- isVersionFolderPath ----------
func TestIsVersionFolderPath(t *testing.T) {
// Reports whether a key sits inside a .versions/ folder, looking at
// the parent segment specifically. The router uses this to skip
// version-file events that need sibling state to classify.
cases := []struct {
key string
want bool
}{
{"obj.versions/v_aaa", true},
{"a/b/obj.versions/v_aaa", true},
{"obj/v_aaa", false}, // parent isn't .versions
{"obj.versions", false}, // the container itself, not a child
// "obj.versions/" reads as the trailing-slash form of the path
// "obj.versions" → leaf is "obj.versions" which ends with the
// suffix → true. The router never sees this shape from the
// reader (events carry concrete leaf names), but pin it here so
// the contract is documented.
{"obj.versions/", true},
{"v_aaa", false}, // no slash at all
{"", false},
}
for _, c := range cases {
t.Run(c.key, func(t *testing.T) {
assert.Equal(t, c.want, isVersionFolderPath(c.key))
})
}
}
// ---------- isDeleteMarkerEntry ----------
func TestIsDeleteMarkerEntry_NilOrEmptyExtendedReturnsFalse(t *testing.T) {
assert.False(t, isDeleteMarkerEntry(nil))
assert.False(t, isDeleteMarkerEntry(&filer_pb.Entry{}))
assert.False(t, isDeleteMarkerEntry(&filer_pb.Entry{Extended: map[string][]byte{}}))
}
func TestIsDeleteMarkerEntry_TrueOnlyForLiteralTrue(t *testing.T) {
// The marker key must be exactly "true"; any other value is not a
// marker. Pinning catches a regression that does case-insensitive
// matching or treats "1" as truthy.
mk := func(val string) *filer_pb.Entry {
return &filer_pb.Entry{Extended: map[string][]byte{s3_constants.ExtDeleteMarkerKey: []byte(val)}}
}
assert.True(t, isDeleteMarkerEntry(mk("true")))
assert.False(t, isDeleteMarkerEntry(mk("True")))
assert.False(t, isDeleteMarkerEntry(mk("TRUE")))
assert.False(t, isDeleteMarkerEntry(mk("1")))
assert.False(t, isDeleteMarkerEntry(mk("")))
assert.False(t, isDeleteMarkerEntry(mk("false")))
}
// ---------- extractTags ----------
func TestExtractTags_NilOrEmptyReturnsNil(t *testing.T) {
assert.Nil(t, extractTags(nil))
assert.Nil(t, extractTags(map[string][]byte{}))
}
func TestExtractTags_OnlyKeysWithObjectTaggingPrefix(t *testing.T) {
// extractTags returns ExtVersionIdKey, Mime, etc. → no.
// It only picks up keys with the AmzObjectTagging prefix and strips
// that prefix to produce the tag map.
prefix := s3_constants.AmzObjectTagging + "-"
ext := map[string][]byte{
prefix + "env": []byte("prod"),
prefix + "team": []byte("data"),
"X-Amz-Other": []byte("ignored"),
"Seaweed-X-Internal": []byte("ignored"),
}
got := extractTags(ext)
require.Len(t, got, 2)
assert.Equal(t, "prod", got["env"])
assert.Equal(t, "data", got["team"])
}
func TestExtractTags_ReturnsNilWhenNoTaggingPrefixedKeys(t *testing.T) {
// Keys with no tagging prefix produce a nil map (not an empty map);
// the router treats nil as "no tags" without an extra branch.
ext := map[string][]byte{
"X-Amz-Other": []byte("ignored"),
"Seaweed-X-Internal": []byte("ignored"),
}
got := extractTags(ext)
assert.Nil(t, got)
}
// ---------- hasActiveEventDrivenAction ----------
func TestHasActiveEventDrivenAction(t *testing.T) {
// Build a snapshot with two action kinds and one of them set to
// scan-only (inactive in event-driven view). hasActiveEventDrivenAction
// must answer true only for the active event-driven kind.
rule := &s3lifecycle.Rule{
ID: "r",
Status: s3lifecycle.StatusEnabled,
ExpirationDays: 7,
AbortMPUDaysAfterInitiation: 3,
}
hash := s3lifecycle.RuleHash(rule)
expirationKey := s3lifecycle.ActionKey{Bucket: "bk", RuleHash: hash, ActionKind: s3lifecycle.ActionKindExpirationDays}
abortKey := s3lifecycle.ActionKey{Bucket: "bk", RuleHash: hash, ActionKind: s3lifecycle.ActionKindAbortMPU}
prior := map[s3lifecycle.ActionKey]engine.PriorState{
expirationKey: {BootstrapComplete: true, Mode: engine.ModeEventDriven},
abortKey: {BootstrapComplete: true, Mode: engine.ModeScanOnly},
}
snap := engine.New().Compile(
[]engine.CompileInput{{Bucket: "bk", Rules: []*s3lifecycle.Rule{rule}}},
engine.CompileOptions{PriorStates: prior},
)
keys := []s3lifecycle.ActionKey{expirationKey, abortKey}
// Active event-driven kind matches.
assert.True(t, hasActiveEventDrivenAction(snap, keys, s3lifecycle.ActionKindExpirationDays))
// Scan-only kind does NOT match — operator promoted it to scan-only
// and the router must respect that by skipping the event-driven path.
assert.False(t, hasActiveEventDrivenAction(snap, keys, s3lifecycle.ActionKindAbortMPU))
// A kind not in the keys list is false.
assert.False(t, hasActiveEventDrivenAction(snap, keys, s3lifecycle.ActionKindNoncurrentDays))
}
func TestHasActiveEventDrivenAction_NilActionSkipped(t *testing.T) {
// A key the snapshot doesn't know about returns nil from Action;
// the helper must skip rather than panic.
snap := engine.New().Compile(nil, engine.CompileOptions{})
keys := []s3lifecycle.ActionKey{
{Bucket: "ghost", ActionKind: s3lifecycle.ActionKindExpirationDays},
}
assert.False(t, hasActiveEventDrivenAction(snap, keys, s3lifecycle.ActionKindExpirationDays))
}
// ---------- engine.Snapshot accessors ----------
func TestSnapshot_BucketVersionedReportsCompiledFlag(t *testing.T) {
rule := &s3lifecycle.Rule{ID: "r", Status: s3lifecycle.StatusEnabled, ExpirationDays: 7}
snap := engine.New().Compile(
[]engine.CompileInput{
{Bucket: "vbk", Rules: []*s3lifecycle.Rule{rule}, Versioned: true},
{Bucket: "ubk", Rules: []*s3lifecycle.Rule{rule}, Versioned: false},
},
engine.CompileOptions{},
)
assert.True(t, snap.BucketVersioned("vbk"))
assert.False(t, snap.BucketVersioned("ubk"))
// Unknown bucket: not versioned, not a panic.
assert.False(t, snap.BucketVersioned("missing"))
}
func TestSnapshot_BucketActionKeysReturnsCompiledList(t *testing.T) {
// Every CompileInput rule emits one action key per RuleActionKind;
// BucketActionKeys must surface them all (regardless of Mode) so
// MatchPath can iterate.
rule := &s3lifecycle.Rule{ID: "r", Status: s3lifecycle.StatusEnabled, ExpirationDays: 7}
snap := engine.New().Compile(
[]engine.CompileInput{{Bucket: "bk", Rules: []*s3lifecycle.Rule{rule}}},
engine.CompileOptions{},
)
keys := snap.BucketActionKeys("bk")
require.NotEmpty(t, keys)
for _, k := range keys {
assert.Equal(t, "bk", k.Bucket)
}
}
func TestSnapshot_BucketActionKeysUnknownBucketReturnsNil(t *testing.T) {
snap := engine.New().Compile(nil, engine.CompileOptions{})
assert.Nil(t, snap.BucketActionKeys("missing"))
}
func TestSnapshot_ActionUnknownKeyReturnsNil(t *testing.T) {
snap := engine.New().Compile(nil, engine.CompileOptions{})
got := snap.Action(s3lifecycle.ActionKey{Bucket: "ghost", ActionKind: s3lifecycle.ActionKindExpirationDays})
assert.Nil(t, got)
}
func TestSnapshot_AllActionsCoversEveryCompiledKind(t *testing.T) {
// AllActions must enumerate every compiled action regardless of
// active state, because the dispatcher uses it for full-snapshot
// reporting.
rule := &s3lifecycle.Rule{
ID: "r",
Status: s3lifecycle.StatusEnabled,
ExpirationDays: 7,
AbortMPUDaysAfterInitiation: 3,
}
snap := engine.New().Compile(
[]engine.CompileInput{{Bucket: "bk", Rules: []*s3lifecycle.Rule{rule}}},
engine.CompileOptions{},
)
all := snap.AllActions()
wantKinds := s3lifecycle.RuleActionKinds(rule)
require.Len(t, all, len(wantKinds))
seen := map[s3lifecycle.ActionKind]bool{}
for _, a := range all {
seen[a.Key.ActionKind] = true
}
for _, k := range wantKinds {
assert.True(t, seen[k], "missing kind %v in AllActions", k)
}
}
func TestSnapshot_SnapshotIDIsMonotonicAcrossRecompiles(t *testing.T) {
// Every Compile call advances snapshotIDSeq; pin that successive
// snapshots from the same Engine carry strictly increasing IDs so
// the dispatcher's stale-snapshot check works.
e := engine.New()
first := e.Compile(nil, engine.CompileOptions{})
second := e.Compile(nil, engine.CompileOptions{})
assert.Greater(t, second.SnapshotID(), first.SnapshotID(),
"second compile must produce a strictly greater snapshot id")
}