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Evil Test Cases
Downloadable test cases for edge cases, DST transitions, and timezone changes. Use these to torture-test your time handling code.
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DST Transition Test Cases
Spring Forward (Non-existent Times)
These times don't exist because clocks "spring forward" at 2:00 AM to 3:00 AM.
# 2024 Spring DST Transitions (Non-existent times)
2024-03-10T02:30:00 America/New_York # EST → EDT
2024-03-10T02:15:00 America/Chicago # CST → CDT
2024-03-10T02:45:00 America/Denver # MST → MDT
2024-03-10T02:30:00 America/Los_Angeles # PST → PDT
2024-03-31T02:30:00 Europe/London # GMT → BST
2024-03-31T02:30:00 Europe/Berlin # CET → CEST
2024-03-31T02:30:00 Europe/Paris # CET → CESTFall Back (Ambiguous Times)
These times occur twice because clocks "fall back" from 2:00 AM to 1:00 AM.
# 2024 Fall DST Transitions (Ambiguous times - occur twice)
2024-11-03T01:30:00 America/New_York # EDT → EST (fold=0 and fold=1)
2024-11-03T01:15:00 America/Chicago # CDT → CST
2024-11-03T01:45:00 America/Denver # MDT → MST
2024-11-03T01:30:00 America/Los_Angeles # PDT → PST
2024-10-27T01:30:00 Europe/London # BST → GMT
2024-10-27T02:30:00 Europe/Berlin # CEST → CET
2024-10-27T02:30:00 Europe/Paris # CEST → CET📅
Leap Year Test Cases
February 29th Edge Cases
# Leap Year Tests
2024-02-29T12:00:00Z # Valid: 2024 is a leap year
2023-02-29T12:00:00Z # Invalid: 2023 is not a leap year
2000-02-29T12:00:00Z # Valid: 2000 is a leap year (divisible by 400)
1900-02-29T12:00:00Z # Invalid: 1900 is not a leap year (divisible by 100, not 400)
2100-02-29T12:00:00Z # Invalid: 2100 is not a leap year
# Leap year arithmetic edge cases
2024-02-29T12:00:00Z + 1 year = ? # Should become 2025-02-28T12:00:00Z
2023-02-28T12:00:00Z + 1 year = ? # Should become 2024-02-28T12:00:00Z (not Feb 29)⏰
Epoch and Timestamp Test Cases
Unix Timestamp Edge Cases
# Unix Timestamp Boundaries
0 # 1970-01-01T00:00:00Z (Unix epoch)
-1 # 1969-12-31T23:59:59Z (before epoch)
2147483647 # 2038-01-19T03:14:07Z (32-bit signed int max)
2147483648 # 2038-01-19T03:14:08Z (32-bit overflow)
4294967295 # 2106-02-07T06:28:15Z (32-bit unsigned int max)
# Milliseconds vs Seconds confusion
1710086400 # 2024-03-10T14:00:00Z (seconds)
1710086400000 # 2024-03-10T14:00:00Z (milliseconds)
1710086400.123 # 2024-03-10T14:00:00.123Z (seconds with fractional)
# JavaScript Date edge cases
new Date(0) # 1970-01-01T00:00:00.000Z
new Date(-1) # 1969-12-31T23:59:59.999Z
new Date(8640000000000000) # Maximum Date value
new Date(8640000000000001) # Invalid DateY2K38 Problem Test Cases
# Y2K38 Problem (32-bit signed integer overflow)
2038-01-19T03:14:07Z # Last valid second (2147483647)
2038-01-19T03:14:08Z # First invalid second (2147483648)
2038-01-19T03:14:09Z # Wraps to 1901-12-13T20:45:53Z on 32-bit systems
# Test these timestamps on 32-bit systems
2147483647 # Should work
2147483648 # May fail or wrap around
4294967295 # Definitely problematic on signed 32-bit🌍
Timezone Test Cases
Timezone Name Confusion
# Ambiguous timezone abbreviations
CST # Central Standard Time (US) or China Standard Time?
IST # India Standard Time or Israel Standard Time?
EST # Eastern Standard Time (US) or Australian Eastern Standard Time?
PST # Pacific Standard Time (US) or Philippine Standard Time?
# Windows vs IANA timezone names
"Pacific Standard Time" # Windows
"America/Los_Angeles" # IANA
"Eastern Standard Time" # Windows
"America/New_York" # IANA
# Historical timezone changes
"Asia/Calcutta" # Old name
"Asia/Kolkata" # New name (same timezone)
"Europe/Kiev" # Old name
"Europe/Kyiv" # New name (same timezone)Political Timezone Changes
# Samoa Date Line Jump (December 30, 2011 never happened)
2011-12-29T23:59:59 Pacific/Apia # Last second of Dec 29
2011-12-31T00:00:00 Pacific/Apia # First second of Dec 31 (skipped Dec 30)
# Russia timezone changes (2014)
2014-10-25T23:59:59 Europe/Moscow # Before change (UTC+4)
2014-10-26T00:00:00 Europe/Moscow # After change (UTC+3)
# Venezuela timezone change (2016)
2016-04-30T23:59:59 America/Caracas # UTC-4:30
2016-05-01T00:00:00 America/Caracas # UTC-4:00
# North Korea timezone change (2018)
2018-05-04T23:59:59 Asia/Pyongyang # UTC+8:30
2018-05-05T00:00:00 Asia/Pyongyang # UTC+9:00📝
Parsing Test Cases
Malformed and Edge Case Inputs
# ISO 8601 edge cases
"2024-02-30T12:00:00Z" # Invalid date (Feb 30)
"2024-13-01T12:00:00Z" # Invalid month (13)
"2024-12-01T25:00:00Z" # Invalid hour (25)
"2024-12-01T12:60:00Z" # Invalid minute (60)
"2024-12-01T12:00:60Z" # Invalid second (60)
# Timezone offset edge cases
"2024-12-01T12:00:00+25:00" # Invalid offset (>24 hours)
"2024-12-01T12:00:00-15:00" # Invalid offset (<-12 hours)
"2024-12-01T12:00:00+00:60" # Invalid minute offset
# Ambiguous formats
"01/02/2024" # Jan 2 or Feb 1?
"2024/1/2" # Jan 2 or Feb 1?
"2024-1-2" # Missing zero padding
# Leap second (not supported by most systems)
"2016-12-31T23:59:60Z" # Leap second
# Empty and null cases
"" # Empty string
null # Null value
undefined # Undefined value
"not a date" # Random string📖
How to Use These Test Cases
Unit Testing
- • Use non-existent times to test error handling
- • Test ambiguous times with both fold values
- • Verify leap year calculations
- • Test timestamp boundary conditions
- • Validate timezone conversion accuracy
Integration Testing
- • Test API endpoints with edge case inputs
- • Verify database storage and retrieval
- • Test timezone-aware scheduling
- • Validate user input parsing
- • Test cross-system time synchronization
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