Add test for drawing line segment with zero length and remove dead co…

…de from intersection_points (#618)

src/drawing/line.rs

@@ -353,6 +353,21 @@ mod tests {
     //   3 / | \ 0
     //   / 2 | 1 \
 
+    #[test]
+    fn test_draw_line_segment_zero_length() {
+        let image = GrayImage::from_pixel(5, 5, Luma([1u8]));
+
+        let expected = gray_image!(
+            1, 1, 1, 1, 1;
+            4, 1, 1, 1, 1;
+            1, 1, 1, 1, 1;
+            1, 1, 1, 1, 1;
+            1, 1, 1, 1, 1);
+
+        let actual = draw_line_segment(&image, (0f32, 1f32), (0f32, 1f32), Luma([4u8]));
+        assert_pixels_eq!(actual, expected);
+    }
+
     #[test]
     fn test_draw_line_segment_horizontal() {
         let image = GrayImage::from_pixel(5, 5, Luma([1u8]));

src/hough.rs

@@ -170,9 +170,6 @@ pub fn intersection_points(
 
     if right_y >= 0.0 && right_y <= h {
         let right_intersect = (w, right_y);
-        if let Some(s) = start {
-            return Some((s, right_intersect));
-        }
         start = Some(right_intersect);
     }