Implement PartialEq.

Resolves #17.

CHANGELOG.md

@@ -12,6 +12,7 @@
 ## [Unreleased]
 
 ### Added
+ * [#17](https://github.com/iliekturtles/uom/issues/17) Implement `PartialEq`.
  * [#26](https://github.com/iliekturtles/uom/issues/26) Implement `num::Zero`.
  * [#35](https://github.com/iliekturtles/uom/issues/35) Implement `num::Saturating`.
  * [#37](https://github.com/iliekturtles/uom/issues/35) Implement `serde::Serialize` and

src/system.rs

@@ -805,6 +805,19 @@ macro_rules! system {
             }
         }
 
+        impl<D, Ul, Ur, V> $crate::lib::cmp::PartialEq<Quantity<D, Ur, V>> for Quantity<D, Ul, V>
+        where
+            D: Dimension + ?Sized,
+            Ul: Units<V> + ?Sized,
+            Ur: Units<V> + ?Sized,
+            V: $crate::num::Num + $crate::Conversion<V>,
+        {
+            #[inline(always)]
+            fn eq(&self, other: &Quantity<D, Ur, V>) -> bool {
+                self.value == change_base::<D, Ul, Ur, V>(&other.value)
+            }
+        }
+
         impl<D, Ul, Ur, V> $crate::lib::ops::Rem<Quantity<D, Ur, V>> for Quantity<D, Ul, V>
         where
             D: Dimension + ?Sized,

src/tests.rs

@@ -518,6 +518,12 @@ mod system_macro {
                             &((*l).clone() / Length::new::<meter>((*r).clone())).value))
             }
 
+            #[allow(trivial_casts)]
+            fn eq(l: A<V>, r: A<V>) -> bool {
+                (*l == *r)
+                    == (Length::new::<meter>((*l).clone()) == Length::new::<meter>((*r).clone()))
+            }
+
             #[allow(trivial_casts)]
             fn rem(l: A<V>, r: A<V>) -> TestResult {
                 if *r == V::zero() {
@@ -811,6 +817,26 @@ mod system_macro {
 }
 
 mod quantities_macro {
+    storage_types! {
+        use tests::*;
+
+        mod f { Q!(tests, super::V); }
+        mod k { Q!(tests, super::V, (kilometer, kilogram)); }
+
+        quickcheck! {
+            #[allow(trivial_casts)]
+            fn eq(l: A<V>, r: A<V>) -> bool {
+                let a = *l == *r;
+                let b = f::Length::new::<meter>((*l).clone())
+                    == k::Length::new::<meter>((*r).clone());
+                let c = k::Length::new::<meter>((*l).clone())
+                    == f::Length::new::<meter>((*r).clone());
+
+                a == b && a == c
+            }
+        }
+    }
+
     mod fractional {
         storage_types! {
             types: Float, Ratio;