From 6f412de2c9522333749b3b18d75aff58be823828 Mon Sep 17 00:00:00 2001
From: Brad Fitzpatrick <brad@danga.com>
Date: Mon, 4 Sep 2023 14:25:42 -0700
Subject: [PATCH] add CompareAndSwap (cas) tests

Signed-off-by: Brad Fitzpatrick <brad@danga.com>
---
 memcache/fakeserver_test.go |  9 ++++++---
 memcache/memcache_test.go   | 22 +++++++++++++++++++---
 2 files changed, 25 insertions(+), 6 deletions(-)

diff --git a/memcache/fakeserver_test.go b/memcache/fakeserver_test.go
index 12c8ffea..6e644bc2 100644
--- a/memcache/fakeserver_test.go
+++ b/memcache/fakeserver_test.go
@@ -71,7 +71,7 @@ func (c *testConn) reply(msg string) bool {
 }
 
 var (
-	writeRx    = regexp.MustCompile(`^(set|add|replace|append|prepend|cas) (\S+) (\d+) (\d+) (\d+)( \S+)?( noreply)?\r\n`)
+	writeRx    = regexp.MustCompile(`^(set|add|replace|append|prepend|cas) (\S+) (\d+) (\d+) (\d+)(?: (\S+))?( noreply)?\r\n`)
 	deleteRx   = regexp.MustCompile(`^delete (\S+)( noreply)?\r\n`)
 	incrDecrRx = regexp.MustCompile(`^(incr|decr) (\S+) (\d+)( noreply)?\r\n`)
 	touchRx    = regexp.MustCompile(`^touch (\S+) (\d+)( noreply)?\r\n`)
@@ -148,7 +148,6 @@ func (c *testConn) handleRequestLine(line string) bool {
 		exptimeVal, _ := strconv.ParseInt(exptimeStr, 10, 64)
 		itemLen, _ := strconv.ParseInt(lenStr, 10, 32)
 		//log.Printf("got %q flags=%q exp=%d %d len=%d cas=%q noreply=%q", verb, key, flags, exptimeVal, itemLen, casUniq, noReply)
-		_ = casUniq // TODO
 		if c.s.m == nil {
 			c.s.m = make(map[string]serverItem)
 		}
@@ -200,7 +199,11 @@ func (c *testConn) handleRequestLine(line string) bool {
 			if !ok {
 				reply("NOT_FOUND")
 			}
-			return false
+			if casUniq != fmt.Sprint(was.casUniq) {
+				return reply("EXISTS")
+			}
+			c.s.m[key] = newItem
+			return reply("STORED")
 		case "append":
 			if !ok {
 				return reply("NOT_STORED")
diff --git a/memcache/memcache_test.go b/memcache/memcache_test.go
index 05f06087..e9e8ec32 100644
--- a/memcache/memcache_test.go
+++ b/memcache/memcache_test.go
@@ -99,20 +99,36 @@ func testWithClient(t *testing.T, c *Client) {
 	mustSet := mustSetF(t, c)
 
 	// Set
-	foo := &Item{Key: "foo", Value: []byte("fooval"), Flags: 123}
+	foo := &Item{Key: "foo", Value: []byte("fooval-fromset"), Flags: 123}
 	err := c.Set(foo)
 	checkErr(err, "first set(foo): %v", err)
 	err = c.Set(foo)
 	checkErr(err, "second set(foo): %v", err)
 
-	// Get
+	// CompareAndSwap
 	it, err := c.Get("foo")
 	checkErr(err, "get(foo): %v", err)
+	if string(it.Value) != "fooval-fromset" {
+		t.Errorf("get(foo) Value = %q, want fooval-romset", it.Value)
+	}
+	it0, err := c.Get("foo") // another get, to fail our CAS later
+	checkErr(err, "get(foo): %v", err)
+	it.Value = []byte("fooval")
+	err = c.CompareAndSwap(it)
+	checkErr(err, "cas(foo): %v", err)
+	it0.Value = []byte("should-fail")
+	if err := c.CompareAndSwap(it0); err != ErrCASConflict {
+		t.Fatalf("cas(foo) error = %v; want ErrCASConflict", err)
+	}
+
+	// Get
+	it, err = c.Get("foo")
+	checkErr(err, "get(foo): %v", err)
 	if it.Key != "foo" {
 		t.Errorf("get(foo) Key = %q, want foo", it.Key)
 	}
 	if string(it.Value) != "fooval" {
-		t.Errorf("get(foo) Value = %q, want fooval", string(it.Value))
+		t.Errorf("get(foo) Value = %q, want fooval", it.Value)
 	}
 	if it.Flags != 123 {
 		t.Errorf("get(foo) Flags = %v, want 123", it.Flags)