Add unit tests and changelog update

Author: alberdingk-thijm

CHANGELOG.md

@@ -8,6 +8,10 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
 
 Added this Changelog.
 
+### Changed
+
+- Merged in [#36](https://github.com/rust-embedded-community/rust-measurements/pull/36) to adjust bounds on `Measurements::pick_appropriate_units()`, which changes the return value for cases when the value is 1.0.
+
 ## [0.10.2]
 
 Merged in [#17](https://github.com/thejpster/rust-measurements/pull/17) to add:

tests/pick_appropriate.rs

@@ -0,0 +1,62 @@
+extern crate measurements;
+
+use measurements::{
+    Measurement,
+    mass::Mass,
+    test_utils::assert_almost_eq,
+};
+
+#[test]
+fn appropriate_units_eq_1() {
+    let val : f64 = 1e0;
+    let mass = Mass::from_kilograms(val);
+    let (s, v) = mass.get_appropriate_units();
+    assert_eq!(s, "kg");
+    assert_almost_eq(val, v);
+}
+
+#[test]
+fn appropriate_units_neg_1() {
+    let val : f64 = -1e0;
+    let mass = Mass::from_kilograms(val);
+    let (s, v) = mass.get_appropriate_units();
+    assert_eq!(s, "kg");
+    assert_almost_eq(val, v);
+}
+
+#[test]
+fn appropriate_units_lt_1() {
+    // units will now be in grams
+    let val : f64 = 1e0 - 1e-3;
+    let mass = Mass::from_kilograms(val);
+    let (s, v) = mass.get_appropriate_units();
+    assert_eq!(s, "g");
+    assert_almost_eq(val * 1e3, v);
+}
+
+#[test]
+fn appropriate_units_gt_1() {
+    let val : f64 = 1e0 + 1e-3;
+    let mass = Mass::from_kilograms(val);
+    let (s, v) = mass.get_appropriate_units();
+    assert_eq!(s, "kg");
+    assert_almost_eq(val, v);
+}
+
+#[test]
+fn appropriate_units_from_grams() {
+    let val : f64 = 1e3;
+    let mass = Mass::from_grams(val);
+    let (s, v) = mass.get_appropriate_units();
+    assert_eq!(s, "kg");
+    assert_almost_eq(val, v * 1e3);
+}
+
+#[test]
+fn appropriate_units_to_grams() {
+    let val : f64 = 1e-3;
+    let mass = Mass::from_kilograms(val);
+    let (s, v) = mass.get_appropriate_units();
+    assert_eq!(s, "g");
+    assert_almost_eq(val * 1e3, v);
+}