Add test coverage for CLIENT UNBLOCK (#7712)

plus minor other fixes to list.tcl

tests/unit/type/list.tcl

@@ -1,3 +1,11 @@
+proc wait_for_blocked_client {} {
+    wait_for_condition 50 100 {
+        [s blocked_clients] ne 0
+    } else {
+        fail "no blocked clients"
+    }
+}
+
 start_server {
     tags {"list"}
     overrides {
@@ -52,7 +60,7 @@ start_server {
 
     test {LPOS when RANK is greater than matches} {
         r DEL mylist
-        r LPUSH l a
+        r LPUSH mylist a
         assert {[r LPOS mylist b COUNT 10 RANK 5] eq {}}
     }
 
@@ -217,6 +225,8 @@ start_server {
         r del list
 
         $rd blpop list 0
+        after 100 ;# Make sure rd is blocked before MULTI
+
         r multi
         r lpush list a
         r del list
@@ -887,4 +897,45 @@ start_server {
         $rd2 close
         r ping
     } {PONG}
+
+    test "client unblock tests" {
+        r del l
+        set rd [redis_deferring_client]
+        $rd client id
+        set id [$rd read]
+
+        # test default args
+        $rd blpop l 0
+        wait_for_blocked_client
+        r client unblock $id
+        assert_equal {} [$rd read]
+
+        # test with timeout
+        $rd blpop l 0
+        wait_for_blocked_client
+        r client unblock $id TIMEOUT
+        assert_equal {} [$rd read]
+
+        # test with error
+        $rd blpop l 0
+        wait_for_blocked_client
+        r client unblock $id ERROR
+        catch {[$rd read]} e
+        assert_equal $e "UNBLOCKED client unblocked via CLIENT UNBLOCK"
+
+        # test with invalid client id
+        catch {[r client unblock asd]} e
+        assert_equal $e "ERR value is not an integer or out of range"
+
+        # test with non blocked client
+        set myid [r client id]
+        catch {[r client unblock $myid]} e
+        assert_equal $e {invalid command name "0"}
+
+        # finally, see the this client and list are still functional
+        $rd blpop l 0
+        wait_for_blocked_client
+        r lpush l foo
+        assert_equal {l foo} [$rd read]
+    } {}
 }