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local system = require("system")
describe("Random:", function()
describe("random()", function()
it("should return random bytes for a valid number of bytes", function()
local num_bytes = 1
local result, err_msg = system.random(num_bytes)
assert.is_nil(err_msg)
assert.is.string(result)
assert.is_equal(num_bytes, #result)
end)
it("should return an empty string for 0 bytes", function()
local num_bytes = 0
local result, err_msg = system.random(num_bytes)
assert.is_nil(err_msg)
assert.are.equal("", result)
end)
it("should return an error message for an invalid number of bytes", function()
local num_bytes = -1
local result, err_msg = system.random(num_bytes)
assert.is.falsy(result)
assert.are.equal("invalid number of bytes, must not be less than 0", err_msg)
end)
it("should not return duplicate results", function()
local num_bytes = 1025
local result1, err_msg = system.random(num_bytes)
assert.is_nil(err_msg)
assert.is.string(result1)
local result2, err_msg = system.random(num_bytes)
assert.is_nil(err_msg)
assert.is.string(result2)
assert.is_not.equal(result1, result2)
end)
end)
describe("rnd()", function()
local has_math_type = type(math.type) == "function"
it("with no args returns a number in [0, 1)", function()
local v, err = system.rnd()
assert.is_nil(err)
assert.is_number(v)
assert.is_true(v >= 0 and v < 1)
end)
it("with no args returns different values on multiple calls", function()
local seen = {}
for _ = 1, 20 do
local v = system.rnd()
seen[v] = true
end
local count = 0
for _ in pairs(seen) do count = count + 1 end
assert.is_true(count >= 2, "expected at least 2 distinct values in 20 calls")
end)
it("with one arg m returns integer in [1, m]", function()
for _ = 1, 50 do
local v, err = system.rnd(6)
assert.is_nil(err)
assert.is_true(v >= 1 and v <= 6 and math.floor(v) == v)
end
end)
it("matches math.random type behaviour for one-arg m when available", function()
if not has_math_type then
return
end
-- use math.random as ground truth for numeric type
local mval = math.random(6)
local rval = system.rnd(6)
assert.are.equal(math.type(mval), math.type(rval))
end)
it("with one arg 1 always returns 1", function()
for _ = 1, 10 do
local v, err = system.rnd(1)
assert.is_nil(err)
assert.are.equal(1, v)
end
end)
it("with one arg 0 returns a full-range integer", function()
local v, err = system.rnd(0)
assert.is_nil(err)
assert.is_true(type(v) == "number" or (math.type and math.type(v) == "integer"))
assert.is_true(v >= -0x8000000000000000 and v <= 0x7fffffffffffffff)
end)
it("matches math.random type behaviour for arg 0 when math.random(0) is supported", function()
if not has_math_type then
return
end
local ok, mval = pcall(math.random, 0)
if not ok then
return -- older Lua where math.random(0) is not supported
end
local rval = system.rnd(0)
assert.are.equal(math.type(mval), math.type(rval))
end)
it("with two args returns integer in [m, n]", function()
for _ = 1, 30 do
local v, err = system.rnd(10, 20)
assert.is_nil(err)
assert.is_true(v >= 10 and v <= 20 and math.floor(v) == v)
end
end)
it("matches math.random type behaviour for two-arg range when available", function()
if not has_math_type then
return
end
local mval = math.random(10, 20)
local rval = system.rnd(10, 20)
assert.are.equal(math.type(mval), math.type(rval))
end)
it("with two args supports negative range", function()
for _ = 1, 30 do
local v, err = system.rnd(-5, 5)
assert.is_nil(err)
assert.is_true(v >= -5 and v <= 5 and math.floor(v) == v)
end
end)
it("with two equal args returns that value", function()
local v, err = system.rnd(7, 7)
assert.is_nil(err)
assert.are.equal(7, v)
end)
it("returns nil and error for empty interval (m > n)", function()
local v, err = system.rnd(10, 5)
assert.is_falsy(v)
assert.are.equal("interval is empty", err)
end)
it("returns nil and error for invalid one-arg (m < 1, m ~= 0)", function()
local v, err = system.rnd(-1)
assert.is_falsy(v)
assert.are.equal("interval is empty", err)
end)
it("returns nil and error for wrong number of arguments", function()
local v, err = system.rnd(1, 2, 3)
assert.is_falsy(v)
assert.are.equal("wrong number of arguments", err)
end)
end)
end)
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