more tests for zrange and zrevrange; fix behavior for out-of-range negative end index

redis.c

@@ -6662,11 +6662,10 @@ static void zrangeGenericCommand(redisClient *c, int reverse) {
     if (start < 0) start = llen+start;
     if (end < 0) end = llen+end;
     if (start < 0) start = 0;
-    if (end < 0) end = 0;
 
-    /* indexes sanity checks */
+    /* Invariant: start >= 0, so this test will be true when end < 0.
+     * The range is empty when start > end or start >= length. */
     if (start > end || start >= llen) {
-        /* Out of range start or start > end result in empty list */
         addReply(c,shared.emptymultibulk);
         return;
     }

tests/unit/type/zset.tcl

@@ -17,6 +17,66 @@ start_server {tags {"zset"}} {
         r zcard ztmp-blabla
     } {0}
 
+    test "ZRANGE basics" {
+        r del ztmp
+        r zadd ztmp 1 a
+        r zadd ztmp 2 b
+        r zadd ztmp 3 c
+        r zadd ztmp 4 d
+
+        assert_equal {a b c d} [r zrange ztmp 0 -1]
+        assert_equal {a b c} [r zrange ztmp 0 -2]
+        assert_equal {b c d} [r zrange ztmp 1 -1]
+        assert_equal {b c} [r zrange ztmp 1 -2]
+        assert_equal {c d} [r zrange ztmp -2 -1]
+        assert_equal {c} [r zrange ztmp -2 -2]
+
+        # out of range start index
+        assert_equal {a b c} [r zrange ztmp -5 2]
+        assert_equal {a b} [r zrange ztmp -5 1]
+        assert_equal {} [r zrange ztmp 5 -1]
+        assert_equal {} [r zrange ztmp 5 -2]
+
+        # out of range end index
+        assert_equal {a b c d} [r zrange ztmp 0 5]
+        assert_equal {b c d} [r zrange ztmp 1 5]
+        assert_equal {} [r zrange ztmp 0 -5]
+        assert_equal {} [r zrange ztmp 1 -5]
+
+        # withscores
+        assert_equal {a 1 b 2 c 3 d 4} [r zrange ztmp 0 -1 withscores]
+    }
+
+    test "ZREVRANGE basics" {
+        r del ztmp
+        r zadd ztmp 1 a
+        r zadd ztmp 2 b
+        r zadd ztmp 3 c
+        r zadd ztmp 4 d
+
+        assert_equal {d c b a} [r zrevrange ztmp 0 -1]
+        assert_equal {d c b} [r zrevrange ztmp 0 -2]
+        assert_equal {c b a} [r zrevrange ztmp 1 -1]
+        assert_equal {c b} [r zrevrange ztmp 1 -2]
+        assert_equal {b a} [r zrevrange ztmp -2 -1]
+        assert_equal {b} [r zrevrange ztmp -2 -2]
+
+        # out of range start index
+        assert_equal {d c b} [r zrevrange ztmp -5 2]
+        assert_equal {d c} [r zrevrange ztmp -5 1]
+        assert_equal {} [r zrevrange ztmp 5 -1]
+        assert_equal {} [r zrevrange ztmp 5 -2]
+
+        # out of range end index
+        assert_equal {d c b a} [r zrevrange ztmp 0 5]
+        assert_equal {c b a} [r zrevrange ztmp 1 5]
+        assert_equal {} [r zrevrange ztmp 0 -5]
+        assert_equal {} [r zrevrange ztmp 1 -5]
+
+        # withscores
+        assert_equal {d 4 c 3 b 2 a 1} [r zrevrange ztmp 0 -1 withscores]
+    }
+
     test {ZRANK basics} {
         r zadd zranktmp 10 x
         r zadd zranktmp 20 y
@@ -69,15 +129,6 @@ start_server {tags {"zset"}} {
         set _ $err
     } {}
 
-    test {ZRANGE and ZREVRANGE basics} {
-        list [r zrange ztmp 0 -1] [r zrevrange ztmp 0 -1] \
-            [r zrange ztmp 1 -1] [r zrevrange ztmp 1 -1]
-    } {{y x z} {z x y} {x z} {x y}}
-
-    test {ZRANGE WITHSCORES} {
-        r zrange ztmp 0 -1 withscores
-    } {y 1 x 10 z 30}
-
     test {ZSETs stress tester - sorting is working well?} {
         set delta 0
         for {set test 0} {$test < 2} {incr test} {