Add integration test for exif copy

tests/metadata.rs

@@ -0,0 +1,37 @@
+use tiff::{
+    decoder::Decoder,
+    encoder::{colortype::Gray8, EncodeMetadataOptions, TiffEncoder},
+    tags::Tag,
+};
+
+#[test]
+fn copies_exif_data() {
+    let src = std::path::PathBuf::from(concat!(
+        env!("CARGO_MANIFEST_DIR"),
+        "/tests/images/predictor-3-gray-f32.tif"
+    ));
+
+    let src = std::fs::File::open(src).unwrap();
+    let mut src = Decoder::new(src).unwrap();
+
+    let mut data = std::io::Cursor::new(vec![]);
+    {
+        let mut dst = TiffEncoder::new(&mut data).unwrap();
+        let mut img = dst.new_image::<Gray8>(1, 1).unwrap();
+
+        let report = img
+            .write_metadata_copy_from(&mut src, EncodeMetadataOptions::default())
+            .unwrap();
+
+        assert_eq!(report.copied, 8);
+        assert_eq!(report.filtered, 0, "There are no tags we do not recognize");
+        img.write_data(&[0x80]).unwrap();
+    }
+
+    data.set_position(0);
+
+    {
+        let mut roundtrip = Decoder::new(data).unwrap();
+        assert!(roundtrip.find_tag(Tag::DateTime).unwrap().is_some());
+    }
+}