tests: cover durationToPrev gap semantics

2 files changed, 30 insertions, 0 deletions

diff --git a/integrationtests/cmd/ioworkload/scenario_open.go b/integrationtests/cmd/ioworkload/scenario_open.go
index 449549c..d86e53b 100644
--- a/integrationtests/cmd/ioworkload/scenario_open.go
+++ b/integrationtests/cmd/ioworkload/scenario_open.go
@@ -6,6 +6,7 @@ import (
 	"path/filepath"
 	"runtime"
 	"syscall"
+	"time"
 	"unsafe"
 )
 
@@ -226,3 +227,31 @@ func openByHandleAtSyscall(mountFD int, handle []byte, flags int) (int, error) {
 	}
 	return int(fd), nil
 }
+
+// openDurationGap creates two openat syscalls separated by a deliberate sleep.
+// Integration tests use this to assert durationToPrev captures inter-syscall gaps.
+func openDurationGap() error {
+	dir, cleanup, err := makeTempDir("open-duration-gap")
+	if err != nil {
+		return err
+	}
+	defer cleanup()
+
+	first := filepath.Join(dir, "gap-first.txt")
+	fd1, err := syscall.Open(first, syscall.O_RDWR|syscall.O_CREAT, 0o644)
+	if err != nil {
+		return fmt.Errorf("open first: %w", err)
+	}
+	if err := syscall.Close(fd1); err != nil {
+		return fmt.Errorf("close first: %w", err)
+	}
+
+	time.Sleep(800 * time.Millisecond)
+
+	second := filepath.Join(dir, "gap-second.txt")
+	fd2, err := syscall.Open(second, syscall.O_RDWR|syscall.O_CREAT, 0o644)
+	if err != nil {
+		return fmt.Errorf("open second: %w", err)
+	}
+	return syscall.Close(fd2)
+}
diff --git a/integrationtests/cmd/ioworkload/scenarios.go b/integrationtests/cmd/ioworkload/scenarios.go
index a6e7a5f..6910314 100644
--- a/integrationtests/cmd/ioworkload/scenarios.go
+++ b/integrationtests/cmd/ioworkload/scenarios.go
@@ -11,6 +11,7 @@ var scenarios = map[string]func() error{
 	"open-basic":                  openBasic,
 	"open-creat":                  openCreat,
 	"open-by-handle-at":           openByHandleAt,
+	"open-duration-gap":           openDurationGap,
 	"open-enoent":                 openEnoent,
 	"open-rdonly-write":           openRdonlyWrite,
 	"open-pid-filter":             openPidFilter,