yin/timestamp_test.go at main · iamseth/yin · GitHub

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package yin

import "testing"

func TestTimestampCompare(t *testing.T) {
	tests := []struct {
		name  string
		left  Timestamp
		right Timestamp
		want  int
	}{
		{
			name:  "equal",
			left:  NewTimestamp(3, ReplicaID("replica-a")),
			right: NewTimestamp(3, ReplicaID("replica-a")),
			want:  0,
		},
		{
			name:  "less by counter",
			left:  NewTimestamp(2, ReplicaID("replica-z")),
			right: NewTimestamp(3, ReplicaID("replica-a")),
			want:  -1,
		},
		{
			name:  "greater by counter",
			left:  NewTimestamp(4, ReplicaID("replica-a")),
			right: NewTimestamp(3, ReplicaID("replica-z")),
			want:  1,
		},
		{
			name:  "less by replica tiebreaker",
			left:  NewTimestamp(5, ReplicaID("replica-a")),
			right: NewTimestamp(5, ReplicaID("replica-b")),
			want:  -1,
		},
		{
			name:  "greater by replica tiebreaker",
			left:  NewTimestamp(5, ReplicaID("replica-b")),
			right: NewTimestamp(5, ReplicaID("replica-a")),
			want:  1,
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			if got := normalizeComparison(tc.left.Compare(tc.right)); got != tc.want {
				t.Fatalf("Timestamp.Compare() = %d, want %d", got, tc.want)
			}
		})
	}
}

func TestTimestampAdvance(t *testing.T) {
	maxCounter := ^uint64(0)

	tests := []struct {
		name          string
		local         Timestamp
		seen          Timestamp
		replica       ReplicaID
		wantCounter   uint64
		wantReplicaID ReplicaID
	}{
		{
			name:          "starts from zero",
			local:         NewTimestamp(0, ReplicaID("replica-a")),
			seen:          NewTimestamp(0, ReplicaID("replica-a")),
			replica:       ReplicaID("replica-a"),
			wantCounter:   1,
			wantReplicaID: ReplicaID("replica-a"),
		},
		{
			name:          "local counter wins",
			local:         NewTimestamp(7, ReplicaID("replica-a")),
			seen:          NewTimestamp(3, ReplicaID("replica-b")),
			replica:       ReplicaID("replica-a"),
			wantCounter:   8,
			wantReplicaID: ReplicaID("replica-a"),
		},
		{
			name:          "seen counter wins",
			local:         NewTimestamp(7, ReplicaID("replica-a")),
			seen:          NewTimestamp(12, ReplicaID("replica-b")),
			replica:       ReplicaID("replica-a"),
			wantCounter:   13,
			wantReplicaID: ReplicaID("replica-a"),
		},
		{
			name:          "equal counters still tick",
			local:         NewTimestamp(12, ReplicaID("replica-a")),
			seen:          NewTimestamp(12, ReplicaID("replica-z")),
			replica:       ReplicaID("replica-a"),
			wantCounter:   13,
			wantReplicaID: ReplicaID("replica-a"),
		},
		{
			name:          "advances to maximum counter",
			local:         NewTimestamp(maxCounter-1, ReplicaID("replica-a")),
			seen:          NewTimestamp(1, ReplicaID("replica-b")),
			replica:       ReplicaID("replica-a"),
			wantCounter:   maxCounter,
			wantReplicaID: ReplicaID("replica-a"),
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			got := tc.local.Advance(tc.seen, tc.replica)
			if got.Counter() != tc.wantCounter {
				t.Fatalf("Advance().Counter() = %d, want %d", got.Counter(), tc.wantCounter)
			}
			if got.ReplicaID() != tc.wantReplicaID {
				t.Fatalf("Advance().ReplicaID() = %q, want %q", got.ReplicaID(), tc.wantReplicaID)
			}
			if got.Compare(tc.local) <= 0 || got.Compare(tc.seen) <= 0 {
				t.Fatalf("Advance() = %#v; want greater than both local %#v and seen %#v", got, tc.local, tc.seen)
			}
		})
	}
}

func TestTimestampAdvancePanicsOnOverflow(t *testing.T) {
	maxCounter := ^uint64(0)
	tests := []struct {
		name  string
		local Timestamp
		seen  Timestamp
	}{
		{
			name:  "local counter already maximum",
			local: NewTimestamp(maxCounter, ReplicaID("replica-a")),
			seen:  NewTimestamp(1, ReplicaID("replica-b")),
		},
		{
			name:  "seen counter already maximum",
			local: NewTimestamp(1, ReplicaID("replica-a")),
			seen:  NewTimestamp(maxCounter, ReplicaID("replica-b")),
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			defer func() {
				recovered := recover()
				if recovered == nil {
					t.Fatal("Advance did not panic on counter overflow")
				}
				if recovered != "yin: timestamp counter overflow" {
					t.Fatalf("Advance panic = %v, want %q", recovered, "yin: timestamp counter overflow")
				}
			}()

			_ = tc.local.Advance(tc.seen, ReplicaID("replica-next"))
		})
	}
}