diff --git a/src/photools3/metadata_writer.py b/src/photools3/metadata_writer.py
index 7c9ce32..bb121cd 100644
--- a/src/photools3/metadata_writer.py
+++ b/src/photools3/metadata_writer.py
@@ -33,7 +33,7 @@ XMP_KEYS_CAPTION: list[XmpKey] = [
     "IPTC:Caption-Abstract",
 ]
 
-XMP_KEYS_TAG: list[XmpKey] = [
+XMP_KEYS_KEYWORDS: list[XmpKey] = [
     "XMP:HierarchicalSubject",
     "XMP:Subject",
     "IPTC:Keywords",
@@ -71,25 +71,26 @@ class MetadataWriter:
         return Path(str(self.path) + ".xmp")
 
     def get_metadata(self, *args, **kwargs) -> Any:
+        path = self.sidecar_path
+        if not path.exists():
+            return ""
         try:
             with exiftool.ExifToolHelper() as exif:
-                metadata = exif.get_metadata([str(self.path)])[0]
+                metadata = exif.get_metadata([path])[0]
         except Exception as exc:  # noqa: BLE001
-            log.error(f"Could not read metadata from {self.path}: {exc}")
-        assert metadata
+            log.error(f"Could not read metadata from {path}: {exc}")
+            return ""
         return metadata.get(*args, **kwargs)
 
     def set_metadata(self, metadata_tags: dict[str, Any]) -> bool:
         if self.sidecar_path.exists():
-            params = ["-overwrite_original"]
+            files, params = [str(self.sidecar_path)], ["-overwrite_original"]
         else:
-            params = ["-o", "%f.xmp"]
+            files, params = [str(self.path)], ["-o", str(self.sidecar_path)]
         try:
             with exiftool.ExifToolHelper() as exif:
-                exif.set_tags(
-                    [str(self.sidecar_path)], tags=metadata_tags, params=params
-                )
-        except Exception as exc:  # noqa
+                exif.set_tags(files, tags=metadata_tags, params=params)
+        except Exception as exc:  # noqa: BLE001
             log.error(f"Could not write metadata to file {self.sidecar_path}: {exc}")
             return False
         return True
@@ -104,9 +105,13 @@ class MetadataWriter:
         metadata_tags = {key: caption for key in XMP_KEYS_CAPTION}
         self.set_metadata(metadata_tags)
 
-    def write_keywords(self, keywords: Keywords): ...
+    def write_keywords(self, keywords: Keywords):
+        # TODO
+        ...
 
-    def write_color(self, color: Color): ...
+    def write_color(self, color: Color):
+        # TODO
+        ...
 
     def write(
         self,
diff --git a/test/test_metadata_writer.py b/test/test_metadata_writer.py
index c397fd5..006b842 100644
--- a/test/test_metadata_writer.py
+++ b/test/test_metadata_writer.py
@@ -1,8 +1,12 @@
+import shutil
 from pathlib import Path
 
 import pytest
 
-from photools3.metadata_writer import MetadataWriter
+from photools3.metadata_writer import (
+    XMP_KEYS_CAPTION,
+    MetadataWriter,
+)
 from test.test_photo import PATHS_DNG_EXAMPLES
 
 
@@ -11,16 +15,12 @@ def make_dng_file(tmp_path):
     def _make(index: int = 0) -> Path:
         src = PATHS_DNG_EXAMPLES[index]
         dst = tmp_path / f"copy_{index}_{src.name}"
+        shutil.copy(src, dst)
         return dst
 
     return _make
 
 
-@pytest.fixture
-def dng_file(make_dng):
-    return make_dng()
-
-
 def test_read_metadata(make_dng_file):
     """primitive test for `MetadataWriter`"""
     file_path = make_dng_file()
@@ -28,28 +28,21 @@ def test_read_metadata(make_dng_file):
     assert result
 
 
-@pytest.mark.parametrize("idx", range(len(PATHS_DNG_EXAMPLES)))
-def test_read_metadata_sidecar_path(make_dng_file, idx):
-    file_path = make_dng_file(idx)
+@pytest.mark.parametrize("pic_no", range(len(PATHS_DNG_EXAMPLES)))
+def test_read_metadata_sidecar_path(make_dng_file, pic_no):
+    file_path = make_dng_file(pic_no)
     metadata_writer = MetadataWriter(file_path)
     print(metadata_writer.sidecar_path)
     assert isinstance(metadata_writer.sidecar_path, Path)
     assert str(metadata_writer.sidecar_path).lower().endswith(".dng.xmp")
 
 
-def test_get_metadata():
-    # TODO: Parametrized test on querying metadata fields
-    ...
-
-
-def test_set_metadata():
-    # TODO: Paramtrized test on setting metadata fields
-    ...
-
-
-def test_set_caption_on_empty():
-    # TODO
-    ...
+@pytest.mark.parametrize("pic_no", range(len(PATHS_DNG_EXAMPLES)))
+def test_set_caption(make_dng_file, pic_no):
+    metadata_writer = MetadataWriter(make_dng_file(pic_no))
+    metadata_writer.write_caption("This is a test")
+    result = metadata_writer.get_metadata(XMP_KEYS_CAPTION[0])
+    assert result
 
 
 def test_set_caption_on_existing():
@@ -57,7 +50,7 @@ def test_set_caption_on_existing():
     ...
 
 
-def test_set_keywords_on_empty():
+def test_set_keywords():
     # TODO
     ...