timezone-data 0.2.0

no_std, no-alloc parser for embedded IANA TZif timezone data: transitions, zone types, POSIX TZ rules, leap seconds, and zone metadata.
Documentation 
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121

//! Ports of gotz's posixtz_test.go.

use timezone_data::{parse_posix_tz, Error, RuleKind};

#[test]
fn parse_simple() {
    let p = parse_posix_tz("EST5EDT,M3.2.0,M11.1.0").unwrap();
    assert_eq!(p.std_abbrev, "EST");
    assert_eq!(p.std_offset, -5 * 3600);
    assert_eq!(p.dst_abbrev, "EDT");
    assert_eq!(p.dst_offset, -4 * 3600);
    assert!(p.has_dst());
    assert_eq!(p.start.kind, RuleKind::MonthWeekDay);
    assert_eq!((p.start.mon, p.start.week, p.start.day), (3, 2, 0));
    assert_eq!(p.end.kind, RuleKind::MonthWeekDay);
    assert_eq!((p.end.mon, p.end.week, p.end.day), (11, 1, 0));
}

#[test]
fn parse_no_dst() {
    let p = parse_posix_tz("JST-9").unwrap();
    assert_eq!(p.std_abbrev, "JST");
    assert_eq!(p.std_offset, 9 * 3600);
    assert!(!p.has_dst());
}

#[test]
fn parse_quoted() {
    let p = parse_posix_tz("<-05>5<-04>,M3.2.0,M11.1.0").unwrap();
    assert_eq!(p.std_abbrev, "-05");
    assert_eq!(p.dst_abbrev, "-04");
}

#[test]
fn parse_with_time() {
    let p = parse_posix_tz("CET-1CEST,M3.5.0/2,M10.5.0/3").unwrap();
    assert_eq!(p.std_abbrev, "CET");
    assert_eq!(p.std_offset, 3600);
    assert_eq!(p.dst_abbrev, "CEST");
    assert_eq!(p.start.time, 7200);
    assert_eq!(p.end.time, 10800);
}

#[test]
fn display_round_trip() {
    for s in [
        "EST5EDT,M3.2.0,M11.1.0",
        "JST-9",
        "CET-1CEST,M3.5.0,M10.5.0/3",
        "<+0330>-3:30<+0430>,J80/0,J264/0", // quoted names + Julian rules
        "EST5EDT,0,365",                    // zero-based day-of-year rules
    ] {
        let p = parse_posix_tz(s).unwrap();
        assert_eq!(p.to_string(), s, "round-trip of {s:?}");
    }
}

#[test]
fn lookup() {
    let p = parse_posix_tz("EST5EDT,M3.2.0,M11.1.0").unwrap();
    // 2024-01-15 12:00:00 UTC — EST.
    assert_eq!(p.lookup(1_705_320_000), ("EST", -18000, false));
    // 2024-07-15 12:00:00 UTC — EDT.
    assert_eq!(p.lookup(1_721_044_800), ("EDT", -14400, true));
}

#[test]
fn transitions_for_year() {
    let p = parse_posix_tz("EST5EDT,M3.2.0,M11.1.0").unwrap();
    let (start, end) = p.transitions_for_year(2024).unwrap();
    // 2024 DST starts March 10 07:00:00 UTC; ends November 3 06:00:00 UTC.
    assert_eq!(start, 1_710_054_000);
    assert_eq!(end, 1_730_613_600);
}

#[test]
fn parse_julian_rule() {
    // Iran-style: quoted names, fractional offset, Julian (Jn) rules with /0 time.
    let p = parse_posix_tz("<+0330>-3:30<+0430>,J80/0,J264/0").unwrap();
    assert_eq!(p.std_abbrev, "+0330");
    assert_eq!(p.std_offset, 3 * 3600 + 30 * 60); // +03:30 east of UTC
    assert_eq!(p.dst_abbrev, "+0430");
    assert_eq!(p.dst_offset, 4 * 3600 + 30 * 60); // default std + 1h
    assert_eq!(p.start.kind, RuleKind::Julian);
    assert_eq!((p.start.day, p.start.time), (80, 0));
    assert_eq!(p.end.kind, RuleKind::Julian);
    assert_eq!((p.end.day, p.end.time), (264, 0));

    // Exercises the Julian branch of the year-second computation (2024 is leap).
    let (start, end) = p.transitions_for_year(2024).unwrap();
    assert!(start < end);
    // Mid-summer (2024-07-15) is within [start, end] -> DST.
    assert_eq!(p.lookup(1_721_044_800), ("+0430", 4 * 3600 + 30 * 60, true));
}

#[test]
fn parse_day_of_year_rule() {
    // Zero-based day-of-year (n) format.
    let p = parse_posix_tz("EST5EDT,0,365").unwrap();
    assert_eq!(p.start.kind, RuleKind::DayOfYear);
    assert_eq!(p.start.day, 0);
    assert_eq!(p.end.kind, RuleKind::DayOfYear);
    assert_eq!(p.end.day, 365);
}

#[test]
fn parse_errors() {
    assert!(matches!(parse_posix_tz(""), Err(Error::BadPosixTz(_))));
    assert!(matches!(parse_posix_tz("EST"), Err(Error::BadPosixTz(_)))); // no offset
    assert!(matches!(
        parse_posix_tz("EST5EDT,M3.2.0"),
        Err(Error::BadPosixTz(_))
    )); // one rule
}

#[test]
fn no_dst_lookup() {
    let p = parse_posix_tz("JST-9").unwrap();
    assert_eq!(p.lookup(1_705_320_000), ("JST", 9 * 3600, false));
    assert!(p.transitions_for_year(2024).is_none());
}