package event

import "testing"

func TestPartitionOf_DeterministicInRange(t *testing.T) {
	const n = 16
	for _, key := range []string{"0", "1", "42", "9007199254740993", "sendA", "list-7"} {
		first := PartitionOf(key, n)
		if first < 0 || first >= n {
			t.Fatalf("PartitionOf(%q, %d) = %d, out of range", key, n, first)
		}
		if again := PartitionOf(key, n); again != first {
			t.Fatalf("PartitionOf(%q, %d) not deterministic: %d vs %d", key, n, first, again)
		}
	}
}

func TestPartitionOf_SameKeySamePartition(t *testing.T) {
	// A session's sessionId must pin every beacon to one partition (per-session
	// FIFO): the same key always hashes to the same partition across callers.
	if PartitionOf("123456789", 32) != PartitionOf("123456789", 32) {
		t.Fatal("same key mapped to different partitions")
	}
}

func TestPartitionOf_SinglePartition(t *testing.T) {
	if PartitionOf("anything", 1) != 0 || PartitionOf("anything", 0) != 0 {
		t.Fatal("n <= 1 must collapse to partition 0")
	}
}

func TestPartitionRoutingKey(t *testing.T) {
	if got := PartitionRoutingKey(7); got != "track.partition.7" {
		t.Fatalf("PartitionRoutingKey(7) = %q", got)
	}
}