Function TestSplitIndexForKeep

pkg/compaction/compaction_test.go:168–228

(t *testing.T)

}

func TestSplitIndexForKeep(t *testing.T) {
	t.Parallel()

	msg := func(role chat.MessageRole, content string) chat.Message {
		return chat.Message{Role: role, Content: content}
	}

	tests := []struct {
		name      string
		messages  []chat.Message
		maxTokens int64
		wantSplit int // expected split index
	}{
		{
			name:      "empty messages",
			messages:  nil,
			maxTokens: 1000,
			wantSplit: 0,
		},
		{
			name: "all messages fit in keep budget - returned len(messages) signals 'compact everything, keep nothing' (the manual /compact contract)",
			messages: []chat.Message{
				msg(chat.MessageRoleUser, "short"),
				msg(chat.MessageRoleAssistant, "short"),
			},
			maxTokens: 100_000,
			wantSplit: 2, // all fit → messages[:2] is everything to compact, messages[2:] is empty (nothing kept)
		},
		{
			name: "recent messages kept, older ones compacted",
			messages: []chat.Message{
				msg(chat.MessageRoleUser, strings.Repeat("a", 40000)),      // ~10005 tokens
				msg(chat.MessageRoleAssistant, strings.Repeat("b", 40000)), // ~10005 tokens
				msg(chat.MessageRoleUser, strings.Repeat("c", 40000)),      // ~10005 tokens
				msg(chat.MessageRoleAssistant, strings.Repeat("d", 40000)), // ~10005 tokens
				msg(chat.MessageRoleUser, strings.Repeat("e", 40000)),      // ~10005 tokens
				msg(chat.MessageRoleAssistant, strings.Repeat("f", 40000)), // ~10005 tokens
			},
			maxTokens: 20_100, // enough for exactly 2 messages
			wantSplit: 4,      // last 2 messages are kept
		},
		{
			name: "snap to assistant boundary even when a tool result fits",
			messages: []chat.Message{
				msg(chat.MessageRoleUser, "u1"),
				msg(chat.MessageRoleAssistant, "a1"),
				msg(chat.MessageRoleTool, "t1"),
			},
			maxTokens: 100_000, // everything fits
			wantSplit: 3,       // all fit → compact everything (returned len)
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			t.Parallel()
			got := SplitIndexForKeep(tt.messages, tt.maxTokens)
			assert.Equal(t, tt.wantSplit, got)