From ebc46cf1c04a00ee779013d3e72dab07fce454e3 Mon Sep 17 00:00:00 2001
From: Denis Shaposhnikov <993498+dsh2dsh@users.noreply.github.com>
Date: Fri, 22 Dec 2023 13:38:14 +0100
Subject: [PATCH] Fix last_n keep rule (#691) (#750)

From https://github.com/zrepl/zrepl/issues/691

The last_n prune rule keeps everything, regardless of if it matches the
regex or not, if there are less than count snapshot. The expectation
would be to never keep non-regex snapshots, regardless of number.
---
 pruning/keep_last_n.go      | 5 -----
 pruning/keep_last_n_test.go | 2 +-
 2 files changed, 1 insertion(+), 6 deletions(-)

diff --git a/pruning/keep_last_n.go b/pruning/keep_last_n.go
index 023568d..73f00cc 100644
--- a/pruning/keep_last_n.go
+++ b/pruning/keep_last_n.go
@@ -33,11 +33,6 @@ func NewKeepLastN(n int, regex string) (*KeepLastN, error) {
 }
 
 func (k KeepLastN) KeepRule(snaps []Snapshot) (destroyList []Snapshot) {
-
-	if k.n > len(snaps) {
-		return []Snapshot{}
-	}
-
 	matching, notMatching := partitionSnapList(snaps, func(snapshot Snapshot) bool {
 		return k.re.MatchString(snapshot.Name())
 	})
diff --git a/pruning/keep_last_n_test.go b/pruning/keep_last_n_test.go
index 4283e3e..17e7394 100644
--- a/pruning/keep_last_n_test.go
+++ b/pruning/keep_last_n_test.go
@@ -90,7 +90,7 @@ func TestKeepLastN(t *testing.T) {
 				stubSnap{"a2", false, o(12)},
 			},
 			rules: []KeepRule{
-				MustKeepLastN(3, "a"),
+				MustKeepLastN(4, "a"),
 			},
 			expDestroy: map[string]bool{
 				"b1": true,