Fix integration test harness: symlink BPF object, increase grace period, improve assertions

- Symlink ior.bpf.o into output dir so ior finds it when run from temp dir
- Increase iorShutdownGrace from 3s to 30s for BPF tracepoint unloading
- Skip records with empty comm in AssertNoUnexpectedComm (BPF race condition)
- Add diagnostic logging (up to 5 samples) in both AssertNoUnexpectedComm
  and AssertNoUnexpectedPID for easier debugging of test failures

Amp-Thread-ID: https://ampcode.com/threads/T-019c814e-d6b6-72fb-aaf0-c49f5b3fd04e
Co-authored-by: Amp <amp@ampcode.com>

2 files changed, 19 insertions, 2 deletions

diff --git a/integrationtests/expectations.go b/integrationtests/expectations.go
index ed155bc..6a816e6 100644
--- a/integrationtests/expectations.go
+++ b/integrationtests/expectations.go
@@ -39,13 +39,21 @@ func AssertEventsPresent(t *testing.T, result TestResult, expected []ExpectedEve
 }
 
 // AssertNoUnexpectedComm verifies all records have the expected comm name.
-// Fails fast on the first mismatch and reports the total count of unexpected records.
+// Records with empty comm are skipped because BPF may capture events before
+// the process name is set in the task struct.
 func AssertNoUnexpectedComm(t *testing.T, result TestResult, expectedComm string) {
 	t.Helper()
 	var count int
 	for _, rec := range result.Records {
+		if rec.Comm == "" {
+			continue
+		}
 		if rec.Comm != expectedComm {
 			count++
+			if count <= 5 {
+				t.Logf("unexpected comm %q (pid=%d tracepoint=%s path=%q)",
+					rec.Comm, rec.Pid, rec.TraceID.String(), rec.Path)
+			}
 		}
 	}
 	if count > 0 {
@@ -62,6 +70,10 @@ func AssertNoUnexpectedPID(t *testing.T, result TestResult, expectedPID int) {
 	for _, rec := range result.Records {
 		if rec.Pid != pid {
 			count++
+			if count <= 5 {
+				t.Logf("unexpected PID %d (tracepoint=%s path=%q comm=%q)",
+					rec.Pid, rec.TraceID.String(), rec.Path, rec.Comm)
+			}
 		}
 	}
 	if count > 0 {
diff --git a/integrationtests/harness.go b/integrationtests/harness.go
index 315fec4..7edde44 100644
--- a/integrationtests/harness.go
+++ b/integrationtests/harness.go
@@ -13,7 +13,7 @@ import (
 
 const (
 	workloadStartupTimeout = 5 * time.Second
-	iorShutdownGrace       = 3 * time.Second
+	iorShutdownGrace       = 30 * time.Second
 )
 
 // TestHarness orchestrates integration tests by starting an ior trace
@@ -109,6 +109,11 @@ func (h *TestHarness) startWorkload(scenario string) (*exec.Cmd, int, error) {
 }
 
 func (h *TestHarness) startIor(pid int, scenario string, duration int) (*exec.Cmd, error) {
+	bpfLink := filepath.Join(h.OutputDir, "ior.bpf.o")
+	if err := os.Symlink(h.BpfObject, bpfLink); err != nil {
+		return nil, fmt.Errorf("symlink bpf object: %w", err)
+	}
+
 	cmd := exec.Command(h.IorBinary,
 		"-pid", strconv.Itoa(pid),
 		"-flamegraph",