diff --git a/swh/indexer/tests/test_metadata.py b/swh/indexer/tests/test_metadata.py
--- a/swh/indexer/tests/test_metadata.py
+++ b/swh/indexer/tests/test_metadata.py
@@ -438,6 +438,28 @@
         # then
         self.assertEqual(expected_results, results)
 
+    def test_detect_metadata_package_uppercase_npm(self):
+        # given
+        df = [
+            {
+                "sha1git": b"def",
+                "name": b"PACKAGE.json",
+                "target": b"def",
+                "length": 897,
+                "status": "visible",
+                "type": "file",
+                "perms": 33188,
+                "dir_id": b"dir_a",
+                "sha1": b"xyz",
+            },
+        ]
+        # when
+        results = detect_metadata(df)
+
+        expected_results = {"NpmMapping": [b"xyz"]}
+        # then
+        self.assertEqual(expected_results, results)
+
     def test_detect_metadata_codemeta_json_uppercase(self):
         # given
         df = [