proc test_memory_efficiency {range} {
    r flushall
    set base_mem [s used_memory]
    set written 0
    for {set j 0} {$j < 10000} {incr j} {
        set key key:$j
        set val [string repeat A [expr {int(rand()*$range)}]]
        r set $key $val
        incr written [string length $key]
        incr written [string length $val]
        incr written 2 ;# A separator is the minimum to store key-value data.
    }
    set current_mem [s used_memory]
    set used [expr {$current_mem-$base_mem}]
    set efficiency [expr {double($written)/$used}]
    return $efficiency
}

start_server {tags {"memefficiency"}} {
    foreach {size_range expected_min_efficiency} {
        32    0.15
        64    0.25
        128   0.35
        1024  0.75
        16384 0.82
    } {
        test "Memory efficiency with values in range $size_range" {
            set efficiency [test_memory_efficiency $size_range]
            assert {$efficiency >= $expected_min_efficiency}
        }
    }
}