71 lines
2.2 KiB
Rust
71 lines
2.2 KiB
Rust
//! Tests for length quantities.
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//!
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//! 长度量的测试。
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use apsis_core::{Quantity, Unit};
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use apsis_units::dimension::Length;
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use apsis_units::{Kilometers, Meters};
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#[test]
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fn stores_the_given_value() {
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assert_eq!(Meters::new(12.5).value(), 12.5);
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assert_eq!(Kilometers::new(-3.0).value(), -3.0);
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}
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#[test]
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fn direct_conversions_are_consistent() {
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assert_eq!(Meters::new(2_500.0).to_kilometers().value(), 2.5);
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assert_eq!(Kilometers::new(2.5).to_meters().value(), 2_500.0);
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}
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#[test]
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fn generic_conversion_matches_direct_conversion() {
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let distance = Meters::new(2_500.0);
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let via_trait: Kilometers = distance.to_unit();
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assert_eq!(via_trait, distance.to_kilometers());
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}
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#[test]
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fn conversion_round_trips() {
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let original = Kilometers::new(42.195);
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let round_tripped: Kilometers = original.to_unit::<Meters>().to_unit();
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assert!((round_tripped.value() - original.value()).abs() < 1e-12);
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}
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#[test]
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fn units_report_their_metadata() {
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fn assert_length<U: Unit<Dimension = Length>>() {}
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assert_eq!(Meters::symbol(), "m");
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assert_eq!(Kilometers::symbol(), "km");
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assert_eq!(Meters::factor_to_base(), 1.0);
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assert_eq!(Kilometers::factor_to_base(), 1_000.0);
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// Both units measure the same dimension, which is what makes the
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// generic conversion above type check.
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// 两种单位测量同一量纲，这正是使上面的泛型换算通过类型检查的原因。
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assert_length::<Meters>();
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assert_length::<Kilometers>();
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}
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#[test]
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fn arithmetic_operates_on_the_stored_value() {
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let sum = Meters::new(1.5) + Meters::new(2.5);
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assert_eq!(sum.value(), 4.0);
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let difference = Meters::new(4.0) - Meters::new(1.0);
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assert_eq!(difference.value(), 3.0);
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let scaled = Meters::new(3.0) * 2.0;
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assert_eq!(scaled.value(), 6.0);
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let straddled = 2.0 * Meters::new(3.0);
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assert_eq!(straddled.value(), 6.0);
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let halved = Meters::new(3.0) / 2.0;
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assert_eq!(halved.value(), 1.5);
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let ratio = Meters::new(3.0) / Meters::new(1.5);
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assert_eq!(ratio, 2.0);
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assert_eq!((-Meters::new(1.0)).value(), -1.0);
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}
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#[test]
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fn display_includes_the_symbol() {
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assert_eq!(Meters::new(1.0).to_string(), "1 m");
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assert_eq!(Kilometers::new(2.0).to_string(), "2 km");
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}
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