183 lines
7.1 KiB
Rust
183 lines
7.1 KiB
Rust
//! Tests for parsing a complete two-line element set.
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//!
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//! 解析完整两行根数集的测试。
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use apsis_time::TimeScale;
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use apsis_tle::{Classification, ElementErrorKind, TwoLineElement};
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/// The sample element set for the International Space Station used by the
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/// `sgp4` reference implementation.
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///
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/// `sgp4` 参考实现所用的国际空间站样本根数集。
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const ISS: &str = concat!(
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"1 25544U 98067A 08264.51782528 -.00002182 00000-0 -11606-4 0 2927\r\n",
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"2 25544 51.6416 247.4627 0006703 130.5360 325.0288 15.72125391563537\r\n",
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);
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#[test]
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fn sample_fields_match_the_reference_parser() {
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let element = TwoLineElement::parse(ISS).expect("sample is well formed");
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assert_eq!(element.name, None);
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assert_eq!(element.satellite_number, 25544);
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assert_eq!(element.classification, Classification::Unclassified);
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assert_eq!(element.international_designator, "98067A");
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assert_eq!(element.element_set_number, 292);
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assert_eq!(element.revolution_number, 56353);
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assert!((element.inclination - 51.6416).abs() < 1e-12);
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assert!((element.right_ascension - 247.4627).abs() < 1e-12);
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assert!((element.eccentricity - 0.0006703).abs() < 1e-15);
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assert!((element.argument_of_perigee - 130.5360).abs() < 1e-12);
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assert!((element.mean_anomaly - 325.0288).abs() < 1e-12);
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assert!((element.mean_motion - 15.72125391).abs() < 1e-9);
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}
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#[test]
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fn exponent_fields_use_an_assumed_decimal_point() {
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let element = TwoLineElement::parse(ISS).expect("sample is well formed");
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// `-11606-4` is -0.11606e-4.
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// `-11606-4` 即 -0.11606e-4。
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assert!((element.bstar - -1.1606e-5).abs() < 1e-18);
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// `00000-0` is zero.
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// `00000-0` 是零。
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assert_eq!(element.mean_motion_double_dot, 0.0);
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// `-.00002182` is written with an explicit decimal point and no leading
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// zero.
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// `-.00002182` 用显式小数点且无前导零写出。
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assert!((element.mean_motion_dot - -2.182e-5).abs() < 1e-18);
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}
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#[test]
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fn epoch_resolves_to_the_expected_day() {
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let element = TwoLineElement::parse(ISS).expect("sample is well formed");
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// The reference parser reports Julian Date 2454730.01782528 for the
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// epoch, which is Modified Julian Date 54729.51782528 on the UTC scale.
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// Day 264 of 2008 is 2008-09-20, and the fraction is 12:25:40.
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// 参考解析器报告该历元为儒略日 2454730.01782528，即 UTC 时标上的约化儒略日
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// 54729.51782528。2008 年的第 264 天是 2008-09-20，零头为 12:25:40。
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let mjd = element
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.epoch
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.mjd(TimeScale::Utc)
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.expect("epoch is covered by the leap table");
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assert!((mjd - 54_729.517_825_28).abs() < 1e-9, "got {mjd}");
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let calendar = element
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.epoch
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.calendar(TimeScale::Utc)
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.expect("epoch is covered by the leap table");
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assert_eq!((calendar.year, calendar.month, calendar.day), (2008, 9, 20));
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assert_eq!(calendar.hour, 12);
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assert_eq!(calendar.minute, 25);
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assert!(
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(calendar.second - 40.104).abs() < 0.01,
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"got {}",
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calendar.second
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);
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}
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#[test]
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fn three_line_form_captures_the_name() {
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let text = format!("ISS (ZARYA)\r\n{ISS}");
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let element = TwoLineElement::parse(&text).expect("three line form is valid");
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assert_eq!(element.name.as_deref(), Some("ISS (ZARYA)"));
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assert_eq!(element.satellite_number, 25544);
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}
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#[test]
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fn line_endings_and_blank_lines_do_not_matter() {
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for text in [
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ISS.replace("\r\n", "\n"),
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format!("\n{ISS}\n"),
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format!(" \n{ISS} \n"),
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ISS.replace("\r\n", "\r\n\n"),
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] {
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assert!(TwoLineElement::parse(&text).is_ok(), "failed for {text:?}");
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}
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}
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#[test]
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fn classification_is_read_from_the_sample() {
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let element = TwoLineElement::parse(ISS).expect("sample is well formed");
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assert_eq!(element.classification.as_char(), 'U');
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let secret = mutate(ISS, 0, 7, 'S');
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let element = TwoLineElement::parse(&secret).expect("valid after checksum fix");
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assert_eq!(element.classification, Classification::Secret);
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}
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/// Replaces the character at the given zero based column of the given zero
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/// based line and recomputes that line's checksum.
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///
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/// 替换给定零基行中给定零基列处的字符，并重算该行的校验和。
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fn mutate(text: &str, line_index: usize, column: usize, replacement: char) -> String {
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let mut lines: Vec<String> = text.lines().map(str::to_string).collect();
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let mut characters: Vec<char> = lines[line_index].chars().collect();
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characters[column] = replacement;
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let body: String = characters[..68].iter().collect();
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let checksum = apsis_tle::line_checksum(&body);
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lines[line_index] = format!("{body}{checksum}");
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format!("{}\r\n{}\r\n", lines[0], lines[1])
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}
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#[test]
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fn mismatched_satellite_numbers_are_rejected() {
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// Change a digit of the second line's satellite number and repair the
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// checksum, so that only the mismatch remains. The satellite number
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// occupies one based columns 3 to 7, which are zero based 2 to 6.
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// 改变第二行卫星编号的一位数字并修复校验和，使只剩下不匹配。卫星编号占据以 1
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// 为基的第 3 至 7 列，即以 0 为基的第 2 至 6 列。
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let text = mutate(ISS, 1, 2, '3');
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let error = TwoLineElement::parse(&text).expect_err("numbers differ");
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assert_eq!(error.kind(), ElementErrorKind::MismatchedElementSet);
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assert_eq!(error.line(), 2);
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}
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#[test]
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fn a_wrong_leading_digit_is_rejected() {
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let text = mutate(ISS, 0, 0, '3');
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let error = TwoLineElement::parse(&text).expect_err("first line must start with 1");
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assert_eq!(error.kind(), ElementErrorKind::UnexpectedCharacter);
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assert_eq!(error.line(), 1);
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}
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#[test]
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fn a_corrupted_checksum_is_reported_with_its_line() {
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let text = ISS.replace("15.72125391563537", "15.72125391563538");
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let error = TwoLineElement::parse(&text).expect_err("checksum fails");
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assert_eq!(error.kind(), ElementErrorKind::Checksum);
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assert_eq!(error.line(), 2);
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}
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#[test]
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fn too_few_lines_are_rejected() {
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let error = TwoLineElement::parse("1 25544U 98067A\n").expect_err("only one line");
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assert_eq!(error.kind(), ElementErrorKind::TooShort);
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}
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#[test]
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fn an_empty_input_is_rejected() {
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assert!(TwoLineElement::parse("").is_err());
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assert!(TwoLineElement::parse("\n\n").is_err());
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}
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#[test]
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fn a_non_numeric_field_is_reported_with_its_columns() {
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// Replace the first inclination digit with a letter, so that the
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// checksum still matches but the field cannot be read.
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// 把第一个倾角数字换成字母，使校验和仍匹配但该字段无法读取。
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let text = mutate(ISS, 1, 8, 'X');
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let error = TwoLineElement::parse(&text).expect_err("inclination is not numeric");
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assert_eq!(error.kind(), ElementErrorKind::InvalidField);
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assert_eq!(error.line(), 2);
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assert_eq!(error.columns(), Some((9, 16)));
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}
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#[test]
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fn a_negative_satellite_number_is_rejected() {
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let text = mutate(ISS, 0, 2, '-');
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let error = TwoLineElement::parse(&text).expect_err("satellite number is not unsigned");
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assert_eq!(error.kind(), ElementErrorKind::InvalidField);
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assert_eq!(error.columns(), Some((3, 7)));
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}
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