Test negative indices in path expressions

tests/jq.test

@@ -1002,6 +1002,28 @@ del(.[1], .[-6], .[2], .[-3:9])
 [0, 1, 2, 3, 4, 5, 6, 7, 8, 9]
 [0, 3, 5, 6, 9]
 
+# negative index
+setpath([-1]; 1)
+[0]
+[1]
+
+pick(.a.b.c)
+null
+{"a":{"b":{"c":null}}}
+
+pick(first)
+[1,2]
+[1]
+
+pick(first|first)
+[[10,20],30]
+[[10]]
+
+# negative indices in path expressions (since last/1 is .[-1])
+pick(last)
+[[10,20],30]
+[null,30]
+
 #
 # Assignment
 #