From 51a4efd970cd9bd33356dd549c223ad095fa57f1 Mon Sep 17 00:00:00 2001
From: mattbatt <matthew.battifarano@gmail.com>
Date: Mon, 19 Jun 2017 22:20:03 -0400
Subject: [PATCH 1/2] Incorrect usage of `abs_sub`

`x.abs_sub(y)` is defined
([confusingly](https://github.com/rust-lang/rust/issues/30315)) as
`max(x-y, 0)`, not `abs(x-y)`. This wasn't caught in tests since `t_x -
t_y` in
[src/algorithm/intersects.rs:48](https://github.com/georust/rust-geo/blob/master/src/algorithm/intersects.rs#L48)
is positive in all of the given examples.
---
 src/algorithm/intersects.rs | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/src/algorithm/intersects.rs b/src/algorithm/intersects.rs
index 8e6e88a4e..bdbaf7d02 100644
--- a/src/algorithm/intersects.rs
+++ b/src/algorithm/intersects.rs
@@ -45,7 +45,7 @@ impl<T> Intersects<Point<T>> for Line<T>
                     t <= T::one()
             },
             (Some(t_x), Some(t_y)) => { // All other lines
-                t_x.abs_sub(t_y) <= T::epsilon()  &&
+                (t_x - t_y).abs() <= T::epsilon()  &&
                     T::zero() <= t_x &&
                     t_x <= T::one()
             }
@@ -442,6 +442,7 @@ mod test {
     #[test]
     fn point_intersects_line_test() {
         let p0 = Point::new(2., 4.);
+        let p1 = Point::new(0., 0.);
         // vertical line
         let line1 = Line::new(Point::new(2., 0.), Point::new(2., 5.));
         // point on line, but outside line segment
@@ -454,6 +455,7 @@ mod test {
         assert!(!p0.intersects(&line2));
         assert!(line3.intersects(&p0));
         assert!(p0.intersects(&line3));
+        assert!(!p1.intersects(&line3));
     }
     #[test]
     fn line_intersects_line_test() {

From 6c3ea2f3ddff40fde99060a1a9fac5c71dd026d5 Mon Sep 17 00:00:00 2001
From: mattbatt <matthew.battifarano@gmail.com>
Date: Tue, 20 Jun 2017 10:57:23 -0400
Subject: [PATCH 2/2] Clarify test cases

---
 src/algorithm/intersects.rs | 18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

diff --git a/src/algorithm/intersects.rs b/src/algorithm/intersects.rs
index bdbaf7d02..61d1ae8c1 100644
--- a/src/algorithm/intersects.rs
+++ b/src/algorithm/intersects.rs
@@ -442,20 +442,34 @@ mod test {
     #[test]
     fn point_intersects_line_test() {
         let p0 = Point::new(2., 4.);
-        let p1 = Point::new(0., 0.);
         // vertical line
         let line1 = Line::new(Point::new(2., 0.), Point::new(2., 5.));
         // point on line, but outside line segment
         let line2 = Line::new(Point::new(0., 6.), Point::new(1.5, 4.5));
         // point on line
         let line3 = Line::new(Point::new(0., 6.), Point::new(3., 3.));
+        // point above line with positive slope
+        let line4 = Line::new(Point::new(1., 2.), Point::new(5., 3.));
+        // point below line with positive slope
+        let line5 = Line::new(Point::new(1., 5.), Point::new(5., 6.));
+        // point above line with negative slope
+        let line6 = Line::new(Point::new(1., 2.), Point::new(5., -3.));
+        // point below line with negative slope
+        let line7 = Line::new(Point::new(1., 6.), Point::new(5., 5.));
         assert!(line1.intersects(&p0));
         assert!(p0.intersects(&line1));
         assert!(!line2.intersects(&p0));
         assert!(!p0.intersects(&line2));
         assert!(line3.intersects(&p0));
         assert!(p0.intersects(&line3));
-        assert!(!p1.intersects(&line3));
+        assert!(!line4.intersects(&p0));
+        assert!(!p0.intersects(&line4));
+        assert!(!line5.intersects(&p0));
+        assert!(!p0.intersects(&line5));
+        assert!(!line6.intersects(&p0));
+        assert!(!p0.intersects(&line6));
+        assert!(!line7.intersects(&p0));
+        assert!(!p0.intersects(&line7));
     }
     #[test]
     fn line_intersects_line_test() {