test(timer): add POSIX timer family end-to-end integration coverage

The POSIX per-process timer family (timer_create, timer_settime,
timer_gettime, timer_getoverrun, timer_delete) had no end-to-end
integration coverage; only the unrelated fd-returning sibling
timerfd_create was exercised. Add a posix-timer-lifecycle workload
scenario and TestPosixTimerLifecycle to validate these are traced as
null_events, and guard against timer_create being misclassified like
timerfd_create (timer_create returns a timer_t via an output pointer,
not an fd, so its records must carry no 'timerfd:' descriptor path).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

1 files changed, 43 insertions, 0 deletions

diff --git a/integrationtests/timer_test.go b/integrationtests/timer_test.go
new file mode 100644
index 0000000..7d9b295
--- /dev/null
+++ b/integrationtests/timer_test.go
@@ -0,0 +1,43 @@
+package integrationtests
+
+import "testing"
+
+// posixTimerTraceArgs restricts tracing to the POSIX timer-family syscalls so
+// the test output is dominated by the lifecycle calls the workload issues.
+// Note: timerfd_create is intentionally NOT in this list — it belongs to the
+// IPC/eventfd family and returns an fd, whereas timer_create returns a timer_t
+// through an output pointer (a null_event in the tracer).
+var posixTimerTraceArgs = []string{
+	"-trace-syscalls",
+	"timer_create,timer_settime,timer_gettime,timer_getoverrun,timer_delete,timerfd_create",
+}
+
+// TestPosixTimerLifecycle verifies the POSIX per-process timer family is traced
+// end-to-end. The workload runs timer_create -> timer_settime -> timer_gettime
+// -> timer_getoverrun -> timer_delete; each must appear as an enter event.
+func TestPosixTimerLifecycle(t *testing.T) {
+	h := newTestHarness(t)
+	result, pid, err := h.RunWithIorArgs("posix-timer-lifecycle", defaultDuration, posixTimerTraceArgs)
+	if err != nil {
+		t.Fatalf("run scenario posix-timer-lifecycle: %v", err)
+	}
+
+	AssertNoUnexpectedPID(t, result, pid)
+	AssertNoUnexpectedComm(t, result, "ioworkload")
+	AssertEventsPresent(t, result, []ExpectedEvent{
+		{Tracepoint: "enter_timer_create", Comm: "ioworkload", MinCount: 1},
+		{Tracepoint: "enter_timer_settime", Comm: "ioworkload", MinCount: 1},
+		{Tracepoint: "enter_timer_gettime", Comm: "ioworkload", MinCount: 1},
+		{Tracepoint: "enter_timer_getoverrun", Comm: "ioworkload", MinCount: 1},
+		{Tracepoint: "enter_timer_delete", Comm: "ioworkload", MinCount: 1},
+	})
+
+	// timer_create is a null_event: it must NOT capture an fd-style path the way
+	// the fd-returning siblings do. In particular it must not be confused with
+	// timerfd_create, whose records carry a "timerfd:" descriptor path. Guard
+	// against that regression: no timer_create record should have a timerfd path.
+	if got := totalTracepointPathCount(result, "enter_timer_create", "timerfd:"); got != 0 {
+		t.Fatalf("enter_timer_create records with a timerfd: descriptor path = %d, want 0; "+
+			"timer_create returns a timer_t, not an fd, and must not be classified like timerfd_create", got)
+	}
+}