Merge #634

634: Add From<Line> for LineString #625 r=michaelkirk a=NolwennD

- [x] I agree to follow the project's [code of conduct](https://github.com/georust/geo/blob/master/CODE_OF_CONDUCT.md).
- [x] I added an entry to `CHANGES.md` if knowledge of this change could be valuable to users.
---

Hello,

Here a small patch for #625, I hope it’s good enough.

Co-authored-by: NolwennD <donolwenn@gmail.com>

geo-types/CHANGES.md

@@ -4,6 +4,8 @@
 
 * Implement `RelativeEq` and `AbsDiffEq` for fuzzy comparison of remaining Geometry Types
   * <https://github.com/georust/geo/pull/628>
+* Implement `From<Line>` for `LineString`
+  * <https://github.com/georust/geo/pull/634>
 
 ## 0.7.1
 

geo-types/src/line_string.rs

@@ -254,6 +254,12 @@ impl<T: CoordNum, IC: Into<Coordinate<T>>> From<Vec<IC>> for LineString<T> {
     }
 }
 
+impl<T: CoordNum> From<Line<T>> for LineString<T> {
+    fn from(line: Line<T>) -> Self {
+        LineString(vec![line.start, line.end])
+    }
+}
+
 /// Turn an iterator of `Point`-like objects into a `LineString`.
 impl<T: CoordNum, IC: Into<Coordinate<T>>> FromIterator<IC> for LineString<T> {
     fn from_iter<I: IntoIterator<Item = IC>>(iter: I) -> Self {
@@ -474,4 +480,21 @@ mod test {
         let ls_oversized: LineString<f32> = coords_x.into_iter().collect();
         assert!(ls.relative_ne(&ls_oversized, 1., 1.));
     }
+
+    #[test]
+    fn should_be_built_from_line() {
+        let start = Coordinate { x: 0, y: 0 };
+        let end = Coordinate { x: 10, y: 10 };
+        let line = Line::new(start, end);
+        let expected = LineString(vec![start, end]);
+
+        assert_eq!(expected, LineString::from(line));
+
+        let start = Coordinate { x: 10., y: 0.5 };
+        let end = Coordinate { x: 10000., y: 10.4 };
+        let line = Line::new(start, end);
+        let expected = LineString(vec![start, end]);
+
+        assert_eq!(expected, LineString::from(line));
+    }
 }