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//! Property-based tests for Base62 encoding
//!
//! **Property 5: LLM Base62 Efficiency**
//! **Validates: Requirements 2.7**
#[cfg(test)]
mod property_tests {
use crate::base62::{decode_base62, encode_base62};
use proptest::prelude::*;
proptest! {
#![proptest_config(ProptestConfig::with_cases(1000))]
/// Property 5a: Base62 encoding SHALL be reversible (round-trip)
///
/// **Property 5: LLM Base62 Efficiency**
/// **Validates: Requirements 2.7**
#[test]
fn prop_base62_round_trip(n in 0u64..u64::MAX / 2) {
let encoded = encode_base62(n);
let decoded = decode_base62(&encoded).unwrap();
prop_assert_eq!(decoded, n, "Round-trip failed for {}: {} -> {}", n, encoded, decoded);
}
/// Property 5b: Base62 encoding SHALL produce shorter strings for large numbers
///
/// For numbers >= 62, Base62 encoding should be more efficient than decimal.
///
/// **Property 5: LLM Base62 Efficiency**
/// **Validates: Requirements 2.7**
#[test]
fn prop_base62_efficiency_for_large_numbers(n in 1000u64..1_000_000u64) {
let base62 = encode_base62(n);
let decimal = n.to_string();
// Base62 should be shorter or equal for numbers >= 62
prop_assert!(
base62.len() <= decimal.len(),
"Base62 ({}) should be <= decimal ({}) for n={}",
base62.len(), decimal.len(), n
);
}
/// Property 5c: Base62 encoding SHALL use only alphanumeric characters
///
/// **Property 5: LLM Base62 Efficiency**
/// **Validates: Requirements 2.7**
#[test]
fn prop_base62_uses_only_alphanumeric(n in 0u64..u64::MAX / 2) {
let encoded = encode_base62(n);
for c in encoded.chars() {
prop_assert!(
c.is_ascii_alphanumeric(),
"Base62 should only use alphanumeric chars, got '{}' in {}",
c, encoded
);
}
}
/// Property 5d: Base62 encoding SHALL be deterministic
///
/// **Property 5: LLM Base62 Efficiency**
/// **Validates: Requirements 2.7**
#[test]
fn prop_base62_deterministic(n in 0u64..u64::MAX / 2) {
let encoded1 = encode_base62(n);
let encoded2 = encode_base62(n);
prop_assert_eq!(encoded1, encoded2, "Encoding should be deterministic");
}
/// Property 5e: Base62 encoding length SHALL grow logarithmically
///
/// **Property 5: LLM Base62 Efficiency**
/// **Validates: Requirements 2.7**
#[test]
fn prop_base62_length_logarithmic(n in 62u64..u64::MAX / 2) {
let encoded = encode_base62(n);
// Expected length is ceil(log62(n))
let expected_len = ((n as f64).log(62.0).ceil()) as usize;
// Allow for rounding differences
prop_assert!(
encoded.len() >= expected_len.saturating_sub(1) && encoded.len() <= expected_len + 1,
"Length {} should be approximately {} for n={}",
encoded.len(), expected_len, n
);
}
/// Property: Invalid Base62 characters SHALL produce errors
///
/// **Validates: Requirements 6.8**
#[test]
fn prop_invalid_chars_produce_errors(
prefix in "[0-9A-Za-z]{0,5}",
invalid in "[^0-9A-Za-z]",
suffix in "[0-9A-Za-z]{0,5}"
) {
let input = format!("{}{}{}", prefix, invalid, suffix);
let result = decode_base62(&input);
prop_assert!(result.is_err(), "Should fail for invalid input: {}", input);
}
}
#[test]
fn test_base62_efficiency_examples() {
// Test specific examples from requirements
let cases = vec![
(320u64, "5A", 2), // 320 -> 5A (2 chars vs 3 decimal)
(540u64, "8i", 2), // 540 -> 8i (2 chars vs 3 decimal)
(10000u64, "2bI", 3), // 10000 -> 2bI (3 chars vs 5 decimal)
(999999u64, "4c91", 4), // 999999 -> 4c91 (4 chars vs 6 decimal)
];
for (n, _expected_prefix, expected_len) in cases {
let encoded = encode_base62(n);
assert_eq!(
encoded.len(),
expected_len,
"Expected {} chars for {}, got {} ({})",
expected_len,
n,
encoded.len(),
encoded
);
// Verify round-trip
let decoded = decode_base62(&encoded).unwrap();
assert_eq!(decoded, n);
}
}
#[test]
fn test_base62_savings_percentage() {
// Calculate average savings for numbers in different ranges
let ranges = vec![
(100u64, 999u64), // 3-digit decimals
(1000u64, 9999u64), // 4-digit decimals
(10000u64, 99999u64), // 5-digit decimals
(100000u64, 999999u64), // 6-digit decimals
];
for (start, end) in ranges {
let mut total_decimal_len = 0;
let mut total_base62_len = 0;
let sample_size = 100;
for i in 0..sample_size {
let n = start + (end - start) * i / sample_size;
total_decimal_len += n.to_string().len();
total_base62_len += encode_base62(n).len();
}
let savings = 1.0 - (total_base62_len as f64 / total_decimal_len as f64);
println!(
"Range {}-{}: {:.1}% savings ({} vs {} chars)",
start,
end,
savings * 100.0,
total_base62_len,
total_decimal_len
);
// Base62 should provide at least 20% savings for 4+ digit numbers
if start >= 1000 {
assert!(
savings > 0.15,
"Expected >15% savings for range {}-{}, got {:.1}%",
start,
end,
savings * 100.0
);
}
}
}
#[test]
fn test_base62_boundary_values() {
// Test boundary values
assert_eq!(encode_base62(0), "0");
assert_eq!(encode_base62(9), "9");
assert_eq!(encode_base62(10), "A");
assert_eq!(encode_base62(35), "Z");
assert_eq!(encode_base62(36), "a");
assert_eq!(encode_base62(61), "z");
assert_eq!(encode_base62(62), "10");
assert_eq!(encode_base62(63), "11");
// Verify round-trips
for n in [0, 9, 10, 35, 36, 61, 62, 63, 100, 1000, 10000] {
let encoded = encode_base62(n);
let decoded = decode_base62(&encoded).unwrap();
assert_eq!(decoded, n, "Round-trip failed for {}", n);
}
}
}