From 0f55c686ef050abdb57fccd196d7208858ad34c8 Mon Sep 17 00:00:00 2001
From: Daniel Schadt <kingdread@gmx.de>
Date: Thu, 27 Nov 2025 22:37:09 +0100
Subject: add preliminary test for heatmap_prepare

---
 hittekaart/src/renderer/mod.rs | 47 ++++++++++++++++++++++++++++++++++++++----
 1 file changed, 43 insertions(+), 4 deletions(-)

diff --git a/hittekaart/src/renderer/mod.rs b/hittekaart/src/renderer/mod.rs
index 40fd5fa..696c1e5 100644
--- a/hittekaart/src/renderer/mod.rs
+++ b/hittekaart/src/renderer/mod.rs
@@ -3,10 +3,7 @@ use std::thread;
 
 use crossbeam_channel::Sender;
 
-use super::{
-    error::Result,
-    gpx::Coordinates,
-};
+use super::{error::Result, gpx::Coordinates};
 
 pub mod heatmap;
 pub mod marktile;
@@ -99,3 +96,45 @@ pub fn colorize<R: Renderer, F: FnMut(RenderedTile) -> Result<()>>(
         colorizer.join().unwrap()
     })
 }
+
+#[cfg(test)]
+mod test {
+    use rstest::rstest;
+    use super::*;
+
+    #[rstest]
+    fn test_heatmap_prepare() {
+        let tracks = &[
+            vec![Coordinates { latitude: 52.520008, longitude: 13.404954 }],
+            vec![Coordinates { latitude: 52.520008, longitude: 13.404954 }],
+            vec![Coordinates { latitude: 52.520008, longitude: 13.404954 }],
+        ];
+        let mut prep = prepare(&heatmap::Renderer, 0, &tracks[..1], || Ok(())).unwrap();
+
+        assert_eq!(prep.tile_count(), 1);
+        assert_eq!(prep.tile_mut(0, 0).get_pixel(0, 0).0[0], 0);
+        assert_eq!(prep.tile_mut(0, 0).get_pixel(255, 255).0[0], 0);
+
+        let ones: &[(u32, u32)] = &[
+            (137, 82),
+            (136, 83),
+            (137, 83),
+            (138, 83),
+            (137, 84),
+        ];
+
+        for (x, y) in ones {
+            assert_eq!(prep.tile_mut(0, 0).get_pixel(*x, *y).0[0], 1);
+        }
+
+        let mut prep = prepare(&heatmap::Renderer, 0, &tracks[..2], || Ok(())).unwrap();
+        for (x, y) in ones {
+            assert_eq!(prep.tile_mut(0, 0).get_pixel(*x, *y).0[0], 2);
+        }
+
+        let mut prep = prepare(&heatmap::Renderer, 0, &tracks[..3], || Ok(())).unwrap();
+        for (x, y) in ones {
+            assert_eq!(prep.tile_mut(0, 0).get_pixel(*x, *y).0[0], 3);
+        }
+    }
+}
-- 
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