nim-stew/tests/test_leb128.nim

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import
unittest, random,
../stew/[byteutils, leb128, results]
const edgeValues = {
0'u64 : "00",
1'u64 : "01",
(1'u64 shl 7) - 1'u64 : "7f",
(1'u64 shl 7) : "8001",
(1'u64 shl 7) + 1'u64 : "8101",
(1'u64 shl 14) - 1'u64 : "ff7f",
(1'u64 shl 14) : "808001",
(1'u64 shl 21) - 1'u64 : "ffff7f",
(1'u64 shl 21) : "80808001",
(1'u64 shl 28) - 1'u64 : "ffffff7f",
(1'u64 shl 28) : "8080808001",
(1'u64 shl 35) - 1'u64 : "ffffffff7f",
(1'u64 shl 35) : "808080808001",
(1'u64 shl 42) - 1'u64 : "ffffffffff7f",
(1'u64 shl 42) : "80808080808001",
(1'u64 shl 49) - 1'u64 : "ffffffffffff7f",
(1'u64 shl 49) : "8080808080808001",
(1'u64 shl 56) - 1'u64 : "ffffffffffffff7f",
(1'u64 shl 56) : "808080808080808001",
(1'u64 shl 63) - 1'u64 : "ffffffffffffffff7f",
(1'u64 shl 63) : "80808080808080808001",
0xFFFF_FFFF_FFFF_FFFF'u64 : "ffffffffffffffffff01"
}
suite "leb128":
template roundtripTest(value: typed) =
let
leb {.inject.} = value.toBytes(Leb128)
roundtripVal = type(value).fromBytes(leb.toOpenArray(), Leb128)
check:
value == roundtripVal.val
test "Success edge cases test":
for pair in edgeValues:
let (value, hex) = pair
roundtripTest value
check:
toHex(leb.toOpenArray()) == hex
test "roundtrip random values":
template testSome(T: type) =
for i in 0..10000:
# TODO nim 1.0 random casts limits to int, so anything bigger will crash
# * sigh *
# https://github.com/nim-lang/Nim/issues/16360
let
v1 = rand(T(0) .. cast[T](int.high))
roundtripTest v1
testSome(uint8)
testSome(uint16)
testSome(uint32)
testSome(uint64)
test "lengths":
const lengths = {
0'u64 : 1,
1'u64 : 1,
(1'u64 shl 7) - 1'u64 : 1,
(1'u64 shl 7) : 2,
(1'u64 shl 7) + 1'u64 : 2,
(1'u64 shl 14) - 1'u64 : 2,
(1'u64 shl 14) : 3,
(1'u64 shl 21) - 1'u64 : 3,
(1'u64 shl 21) : 4,
(1'u64 shl 28) - 1'u64 : 4,
(1'u64 shl 28) : 5,
(1'u64 shl 35) - 1'u64 : 5,
(1'u64 shl 35) : 6,
(1'u64 shl 42) - 1'u64 : 6,
(1'u64 shl 42) : 7,
(1'u64 shl 49) - 1'u64 : 7,
(1'u64 shl 49) : 8,
(1'u64 shl 56) - 1'u64 : 8,
(1'u64 shl 56) : 9,
(1'u64 shl 63) - 1'u64 : 9,
(1'u64 shl 63) : 10,
0xFFFF_FFFF_FFFF_FFFF'u64 : 10
}
for pair in lengths:
check: Leb128.len(pair[0]) == pair[1]
test "errors":
check:
uint8.fromBytes([0x80'u8], Leb128) == (0'u8, 0'i8)
uint8.fromBytes([0x80'u8, 0x80], Leb128) == (0'u8, 0'i8)
uint8.fromBytes(toBytes(256'u16, Leb128).toOpenArray(), Leb128).len < 0
uint8.fromBytes([0x80'u8, 0x02], Leb128) == (0'u8, -2'i8) # 2 bytes consumed and overflow
uint8.fromBytes([0x80'u8, 0x02, 0x05], Leb128) == (0'u8, -2'i8) # 2 bytes consumed and overflow
uint64.fromBytes([0xff'u8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x02], Leb128).len < 0
uint64.fromBytes([0xff'u8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff], Leb128) == (0'u64, 0'i8)
check:
uint8.scan([0x80'u8], Leb128) == 0
uint8.scan([0x80'u8, 0x80], Leb128) == 0
uint8.scan(toBytes(256'u16, Leb128).toOpenArray(), Leb128) < 0
uint64.scan([0xff'u8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0x02], Leb128) < 0
uint64.scan([0xff'u8, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff, 0xff], Leb128) == 0