Make tests that wait for concurrent work wait on the event or a condition with a long deadline (issue 1814)

A test that slept a fixed time and then asserted what a goroutine, process or
watcher did failed under the checker's load. Each now waits for its positive
evidence (a started baseline, a call counted, a state reached) within 30 s, and
the concurrency-limit tests meet at a barrier instead of overlapping by sleep.

Claude-Session: https://claude.ai/code/session_01NcbgfJ9Gum47zkFKWRaovL

modules/i3/cmd/i3-tools/i3_test.go

@@ -310,7 +310,8 @@ func TestTheWatcherReloadsOnceAfterAChangeAndNeverIntoErrors(t *testing.T) {
 	stop := make(chan struct{})
 	defer close(stop)
 	go w.Run(stop)
-	time.Sleep(60 * time.Millisecond)
+	// the baseline is taken once Since is set; a change written before that would be part of it
+	waitFor(t, func() bool { return w.Status().Since != "" })
 	os.MkdirAll(filepath.Join(dir, "config.d"), 0o755)
 	os.WriteFile(filepath.Join(dir, "config.d", "50-x.conf"), []byte("b"), 0o644)
 	os.WriteFile(filepath.Join(dir, "config"), []byte("aa"), 0o644)
@@ -342,15 +343,21 @@ func TestAtItsStartTheWatcherReloadsWhatTheRunningI3HasNotLoaded(t *testing.T) {
 		{map[string]string{cfg: "new", filepath.Join(dir, "config.d", "gone.conf"): "x"}, 1},
 	} {
 		var mu sync.Mutex
-		reloads := 0
+		reloads, asked := 0, 0
 		w := &Watcher{Dir: dir, Every: 10 * time.Millisecond,
 			Check:  func() ([]ConfigError, error) { return nil, nil },
 			Reload: func() error { mu.Lock(); reloads++; mu.Unlock(); return nil },
-			Loaded: func() (map[string]string, error) { return c.loaded, nil },
+			Loaded: func() (map[string]string, error) { mu.Lock(); asked++; mu.Unlock(); return c.loaded, nil },
 		}
 		stop := make(chan struct{})
 		go w.Run(stop)
-		time.Sleep(80 * time.Millisecond)
+		// positive evidence first: the watcher asked i3 what it has loaded, then reloads
+		// (want 1) or has had many rounds to do so (want 0)
+		waitFor(t, func() bool { mu.Lock(); defer mu.Unlock(); return asked > 0 })
+		if c.want > 0 {
+			waitFor(t, func() bool { mu.Lock(); defer mu.Unlock(); return reloads >= c.want })
+		}
+		time.Sleep(100 * time.Millisecond)
 		close(stop)
 		mu.Lock()
 		if reloads != c.want {
@@ -361,11 +368,12 @@ func TestAtItsStartTheWatcherReloadsWhatTheRunningI3HasNotLoaded(t *testing.T) {
 }
 
 func waitFor(t *testing.T, ok func() bool) {
-	for i := 0; i < 200; i++ {
+	t.Helper()
+	for i := 0; i < 3000; i++ {
 		if ok() {
 			return
 		}
 		time.Sleep(10 * time.Millisecond)
 	}
-	t.Fatal("timed out")
+	t.Fatal("timed out after 30 s")
 }