sww tests: wait for every starting line as long as the start takes (closes #331)

Each test in internal/sww that waits for the starting line now waits until
the line is written or sww exits, so a slow Core Rule Set compile on a
loaded host no longer fails it. The two tests that run sww as a child
process get its exit status from a goroutine that waits on it, and no
longer kill it after 30 seconds; the waits after SIGTERM still end after
waitLimit. startRProxyProcess returns a stop function in place of the
process and its output.

Model: opus-5-5

internal/sww/waf_test.go

@@ -54,12 +54,9 @@ func TestMainRunsWAF(t *testing.T) {
 		t.Fatalf("find the test binary: %v", err)
 	}
 
-	ctx, cancel := context.WithTimeout(t.Context(), 3*waitLimit)
-	defer cancel()
-
 	dir := t.TempDir()
 	out := &output{}
-	cmd := exec.CommandContext(ctx, binary) //nolint:gosec // this test binary
+	cmd := exec.CommandContext(t.Context(), binary) //nolint:gosec // this test binary
 	cmd.Stdout = out
 
 	cmd.Env = append(os.Environ(),
@@ -75,12 +72,14 @@ func TestMainRunsWAF(t *testing.T) {
 		t.Fatalf("start: %v", err)
 	}
 
-	t.Cleanup(func() {
-		_ = cmd.Process.Kill()
-		_ = cmd.Wait()
-	})
+	exited := make(chan int, 1)
 
-	starting := out.line(t, "msg", "starting")
+	go func() {
+		_ = cmd.Wait()
+		exited <- cmd.ProcessState.ExitCode()
+	}()
+
+	starting := out.lineBeforeExit(t, "starting", exited)
 	addr, _ := starting["address"].(string)
 	ask(t, addr, "/", http.StatusOK, waf.DispositionAllow)
 
@@ -90,9 +89,13 @@ func TestMainRunsWAF(t *testing.T) {
 		t.Fatalf("signal: %v", err)
 	}
 
-	err = cmd.Wait()
-	if err != nil {
-		t.Fatalf("exit: %v; output:\n%s", err, out.text())
+	select {
+	case status := <-exited:
+		if status != 0 {
+			t.Fatalf("exit status %d, want 0; output:\n%s", status, out.text())
+		}
+	case <-time.After(waitLimit):
+		t.Fatal("still running after being told to stop")
 	}
 
 	wantUTC(t, "the process line", starting["time"])
@@ -215,7 +218,7 @@ func runWAF(t *testing.T, env map[string]string, use func(addr string)) {
 		exited <- run(ctx, env, out)
 	}()
 
-	addr, _ := out.line(t, "msg", "starting")["address"].(string)
+	addr, _ := out.lineBeforeExit(t, "starting", exited)["address"].(string)
 	use(addr)
 	stop()