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# frozen_string_literal: true
require_relative 'test_helper'
begin
require 'bigdecimal'
rescue LoadError
end
class JSONRyuFallbackTest < Test::Unit::TestCase
include JSON
# Test that numbers with more than 17 significant digits fall back to rb_cstr_to_dbl
def test_more_than_17_significant_digits
# These numbers have > 17 significant digits and should use fallback path
# They should still parse correctly, just not via the Ryu optimization
test_cases = [
# input, expected (rounded to double precision)
["1.23456789012345678901234567890", 1.2345678901234567],
["123456789012345678.901234567890", 1.2345678901234568e+17],
["0.123456789012345678901234567890", 0.12345678901234568],
["9999999999999999999999999999.9", 1.0e+28],
# Edge case: exactly 18 digits
["123456789012345678", 123456789012345680.0],
# Many fractional digits
["0.12345678901234567890123456789", 0.12345678901234568],
]
test_cases.each do |input, expected|
result = JSON.parse(input)
assert_in_delta(expected, result, 1e-10,
"Failed to parse #{input} correctly (>17 digits, fallback path)")
end
end
# Test decimal_class option forces fallback
def test_decimal_class_option
input = "3.141"
# Without decimal_class: uses Ryu, returns Float
result_float = JSON.parse(input)
assert_instance_of(Float, result_float)
assert_equal(3.141, result_float)
# With decimal_class: uses fallback, returns BigDecimal
result_bigdecimal = JSON.parse(input, decimal_class: BigDecimal)
assert_instance_of(BigDecimal, result_bigdecimal)
assert_equal(BigDecimal("3.141"), result_bigdecimal)
end if defined?(::BigDecimal)
# Test that numbers with <= 17 digits use Ryu optimization
def test_ryu_optimization_used_for_normal_numbers
test_cases = [
["3.141", 3.141],
["1.23456789012345e100", 1.23456789012345e100],
["0.00000000000001", 1.0e-14],
["123456789012345.67", 123456789012345.67],
["-1.7976931348623157e+308", -1.7976931348623157e+308],
["2.2250738585072014e-308", 2.2250738585072014e-308],
# Exactly 17 significant digits
["12345678901234567", 12345678901234567.0],
["1.2345678901234567", 1.2345678901234567],
]
test_cases.each do |input, expected|
result = JSON.parse(input)
assert_in_delta(expected, result, expected.abs * 1e-15,
"Failed to parse #{input} correctly (<=17 digits, Ryu path)")
end
end
# Test edge cases at the boundary (17 digits)
def test_seventeen_digit_boundary
# Exactly 17 significant digits should use Ryu
input_17 = "12345678901234567.0" # Force it to be a float with .0
result = JSON.parse(input_17)
assert_in_delta(12345678901234567.0, result, 1e-10)
# 18 significant digits should use fallback
input_18 = "123456789012345678.0"
result = JSON.parse(input_18)
# Note: This will be rounded to double precision
assert_in_delta(123456789012345680.0, result, 1e-10)
end
# Test that leading zeros don't count toward the 17-digit limit
def test_leading_zeros_dont_count
test_cases = [
["0.00012345678901234567", 0.00012345678901234567], # 17 significant digits
["0.000000000000001234567890123456789", 1.234567890123457e-15], # >17 significant
]
test_cases.each do |input, expected|
result = JSON.parse(input)
assert_in_delta(expected, result, expected.abs * 1e-10,
"Failed to parse #{input} correctly")
end
end
# Test that Ryu handles special values correctly
def test_special_double_values
test_cases = [
["1.7976931348623157e+308", Float::MAX], # Largest finite double
["2.2250738585072014e-308", Float::MIN], # Smallest normalized double
]
test_cases.each do |input, expected|
result = JSON.parse(input)
assert_in_delta(expected, result, expected.abs * 1e-10,
"Failed to parse #{input} correctly")
end
# Test zero separately
result_pos_zero = JSON.parse("0.0")
assert_equal(0.0, result_pos_zero)
# Note: JSON.parse doesn't preserve -0.0 vs +0.0 distinction in standard mode
result_neg_zero = JSON.parse("-0.0")
assert_equal(0.0, result_neg_zero.abs)
end
# Test subnormal numbers that caused precision issues before fallback was added
# These are extreme edge cases discovered by fuzzing (4 in 6 billion numbers tested)
def test_subnormal_edge_cases_round_trip
# These subnormal numbers (~1e-310) had 1 ULP rounding errors in original Ryu
# They now use rb_cstr_to_dbl fallback for exact precision
test_cases = [
"-3.2652630314355e-310",
"3.9701623107025e-310",
"-3.6607772435415e-310",
"2.9714076801985e-310",
]
test_cases.each do |input|
# Parse the number
result = JSON.parse(input)
# Should be bit-identical
assert_equal(result, JSON.parse(result.to_s),
"Subnormal #{input} failed round-trip test")
# Should be bit-identical
assert_equal(result, JSON.parse(JSON.dump(result)),
"Subnormal #{input} failed round-trip test")
# Verify the value is in the expected subnormal range
assert(result.abs < 2.225e-308,
"#{input} should be subnormal (< 2.225e-308)")
end
end
# Test invalid numbers are properly rejected
def test_invalid_numbers_rejected
invalid_cases = [
"-",
".",
"-.",
"-.e10",
"1.2.3",
"1e",
"1e+",
]
invalid_cases.each do |input|
assert_raise(JSON::ParserError, "Should reject invalid number: #{input}") do
JSON.parse(input)
end
end
end
end
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