My AI agent said “All tests passed!” So I asked for receipts.

import re

def iso_duration_seconds(s):
    if not isinstance(s, str):
        raise ValueError("Input must be string")
    if s == "" or s == "P" or s == "PT":
        raise ValueError("Invalid duration")
    # Must start with P
    if not s.startswith('P'):
        raise ValueError("Duration must start with 'P'")
    # Split date and time parts
    if 'T' in s:
        date_part, time_part = s[1:].split('T', 1)
    else:
        date_part, time_part = s[1:], ''
    # Validate no unsupported units Y or M anywhere
    if re.search(r'[YM]', s):
        raise ValueError("Years and months not supported")
    total = 0.0
    # Parse date part: only D allowed
    if date_part:
        # Expect pattern like (\d+(\.\d+)?)D
        m = re.fullmatch(r'(\d+(?:\.\d+)?)D', date_part)
        if not m:
            raise ValueError("Invalid date part")
        days = float(m.group(1))
        total += days * 86400
    # Parse time part: H, M, S allowed, order not enforced but we parse sequentially
    if time_part:
        # Remove possible empty
        # Use regex to find all number+unit
        tokens = re.findall(r'(\d+(?:\.\d+)?)([HMS])', time_part)
        if not tokens:
            raise ValueError("Invalid time part")
        # Ensure we consumed whole string
        reconstructed = ''.join(num + unit for num, unit in tokens)
        if reconstructed != time_part:
            raise ValueError("Invalid time part format")
        for num, unit in tokens:
            val = float(num)
            if unit == 'H':
                total += val * 3600
            elif unit == 'M':
                total += val * 60
            elif unit == 'S':
                total += val
            else:
                raise ValueError("Unsupported unit")
    # Ensure at least one component contributed
    if total == 0 and s not in ("PT0S",):  # allow zero explicitly
        # but also PT0S should be allowed
        # check if any number present
        if not re.search(r'\d', s):
            raise ValueError("No duration specified")
    return total

# Tests
test_cases = [
    ("PT0S", 0),
    ("PT1H30M", 5400),
    ("P1DT2H", 93600),
    ("P1W", 604800),
    ("PT0.5S", 0.5),
    ("P2DT3H4M5.25S", 183845.25),
]
errors = ["", "P", "PT", "1H", "P1H"]

all_passed = True
for inp, expected in test_cases:
    try:
        result = iso_duration_seconds(inp)
        if abs(result - expected) > 1e-9:
            print(f"FAIL: {inp} -> {result}, expected {expected}")
            all_passed = False
        else:
            print(f"PASS: {inp} -> {result}")
    except Exception as e:
        print(f"ERROR: {inp} raised {e}")
        all_passed = False

for inp in errors:
    try:
        result = iso_duration_seconds(inp)
        print(f"FAIL (should error): {inp} -> {result}")
        all_passed = False
    except ValueError:
        print(f"PASS (error): {inp} raised ValueError")
    except Exception as e:
        print(f"FAIL (wrong exception): {inp} raised {e}")
        all_passed = False

if all_passed:
    print("\nAll tests passed!")
else:
    print("\nSome tests failed.")

import re

def iso_duration_seconds(s):
    if not isinstance(s, str):
        raise ValueError("Input must be string")
    if s == "" or s == "P" or s == "PT":
        raise ValueError("Invalid duration")
    if not s.startswith('P'):
        raise ValueError("Duration must start with 'P'")
    rest = s[1:]
    # Split into date and time parts
    if 'T' in rest:
        date_part, time_part = rest.split('T', 1)
    else:
        date_part, time_part = rest, ''
    # Years and months not allowed anywhere
    if re.search(r'[YM]', s):
        # But allow M as minute only if after T? Simpler: reject any M or Y.
        # However we need to allow M for minutes. So we check for Y only.
        if 'Y' in s:
            raise ValueError("Years and months not supported")
        # For M, we need to ensure it's not a month. Since we don't support months,
        # any M appearing before T is month. So check date_part for M.
        if 'M' in date_part:
            raise ValueError("Years and months not supported")
    total = 0.0
    # Parse date part: D and/or W allowed
    if date_part:
        # Find all number+unit pairs
        matches = re.findall(r'(\d+(?:\.\d+)?)([DW])', date_part)
        if not matches:
            raise ValueError("Invalid date part")
        # Ensure we consumed the whole date_part
        reconstructed = ''.join(num + unit for num, unit in matches)
        if reconstructed != date_part:
            raise ValueError("Invalid date part format")
        for num, unit in matches:
            val = float(num)
            if unit == 'D':
                total += val * 86400
            elif unit == 'W':
                total += val * 7 * 86400
            else:
                raise ValueError("Unsupported date unit")
    # Parse time part: H, M, S allowed
    if time_part:
        matches = re.findall(r'(\d+(?:\.\d+)?)([HMS])', time_part)
        if not matches:
            raise ValueError("Invalid time part")
        reconstructed = ''.join(num + unit for num, unit in matches)
        if reconstructed != time_part:
            raise ValueError("Invalid time part format")
        for num, unit in matches:
            val = float(num)
            if unit == 'H':
                total += val * 3600
            elif unit == 'M':
                total += val * 60
            elif unit == 'S':
                total += val
            else:
                raise ValueError("Unsupported time unit")
    # Ensure at least one component contributed (except PT0S already handled)
    if total == 0:
        # Check if there was any number at all
        if not re.search(r'\d', s):
            raise ValueError("No duration specified")
    return total

# Tests
test_cases = [
    ("PT0S", 0),
    ("PT1H30M", 5400),
    ("P1DT2H", 93600),
    ("P1W", 604800),
    ("PT0.5S", 0.5),
    ("P2DT3H4M5.25S", 183845.25),
]
errors = ["", "P", "PT", "1H", "P1H"]

all_passed = True
for inp, expected in test_cases:
    try:
        result = iso_duration_seconds(inp)
        if abs(result - expected) > 1e-9:
            print(f"FAIL: {inp} -> {result}, expected {expected}")
            all_passed = False
        else:
            print(f"PASS: {inp} -> {result}")
    except Exception as e:
        print(f"ERROR: {inp} raised {e}")
        all_passed = False

for inp in errors:
    try:
        result = iso_duration_seconds(inp)
        print(f"FAIL (should error): {inp} -> {result}")
        all_passed = False
    except ValueError:
        print(f"PASS (error): {inp} raised ValueError")
    except Exception as e:
        print(f"FAIL (wrong exception): {inp} raised {e}")
        all_passed = False

if all_passed:
    print("\nAll tests passed!")
else:
    print("\nSome tests failed.")