Refactor for readability

internal/store/store_test.go

@@ -0,0 +1,24 @@
+package store
+
+import (
+	"testing"
+	"time"
+)
+
+func TestTrimHistoryToMaxPoints(t *testing.T) {
+	s := &Store{}
+	base := time.Date(2026, 4, 20, 0, 0, 0, 0, time.UTC)
+	s.history = make([]Sample, 0, MaxHistoryPoints+25)
+	for i := 0; i < MaxHistoryPoints+25; i++ {
+		s.history = append(s.history, Sample{At: base.Add(time.Duration(i) * time.Second), Value: i})
+	}
+
+	s.trimHistoryLocked(base.Add(time.Duration(MaxHistoryPoints+25) * time.Second))
+
+	if got := len(s.history); got != MaxHistoryPoints {
+		t.Fatalf("history length = %d, want %d", got, MaxHistoryPoints)
+	}
+	if s.history[0].Value != 25 {
+		t.Fatalf("oldest retained value = %d, want %d", s.history[0].Value, 25)
+	}
+}