From 61b3027f38f49150e39baebaa1c0d8513e983ddd Mon Sep 17 00:00:00 2001
From: "A. Molzer" <5550310+197g@users.noreply.github.com>
Date: Thu, 13 Nov 2025 23:38:15 +0100
Subject: [PATCH] Test reading planes of a whole image

---
 tests/decode_planes.rs | 31 +++++++++++++++++++++++++++++++
 1 file changed, 31 insertions(+)
 create mode 100644 tests/decode_planes.rs

diff --git a/tests/decode_planes.rs b/tests/decode_planes.rs
new file mode 100644
index 0000000..fcaff01
--- /dev/null
+++ b/tests/decode_planes.rs
@@ -0,0 +1,31 @@
+use tiff::decoder::Decoder;
+
+use std::fs::File;
+use std::path::PathBuf;
+
+const TEST_IMAGE_DIR: &str = "./tests/images/";
+
+#[test]
+fn read_all_planes() {
+    let path = PathBuf::from(TEST_IMAGE_DIR).join("planar-rgb-u8.tif");
+    let file = File::open(path).unwrap();
+    let io = std::io::BufReader::new(file);
+
+    let mut tif = Decoder::new(io).unwrap();
+    let layout = tif.image_buffer_layout().unwrap();
+    assert_eq!(layout.planes, 3);
+    let plane_stride = layout.plane_stride.map_or(0, |x| x.get());
+
+    let mut buffer = vec![0u8; layout.planes * plane_stride];
+    tif.read_image_bytes(&mut buffer).unwrap();
+
+    // Mainly you can see: these are different and non-zero. Otherwise these magic constants just
+    // depend on the file itself that is being used.
+    const PLANE_EXCPECTED_SUMS: [u32; 3] = [15417630, 13007788, 11103530];
+
+    for (plane, expected) in (0..layout.planes).zip(PLANE_EXCPECTED_SUMS) {
+        let plane_data = &buffer[plane_stride * plane..][..layout.len];
+        let sum: u32 = plane_data.iter().copied().map(u32::from).sum();
+        assert_eq!(sum, expected);
+    }
+}