adds tests for guess_media_type

removes unnecessary comments

lbry/schema/mime_types.py

@@ -183,20 +183,17 @@ def guess_media_type(path):
     _, ext = os.path.splitext(path)
     extension = ext.strip().lower()
 
-    # try detecting real file format if path points to a readable file
     try:
         kind = filetype.guess(path)
         if kind:
             real_extension = f".{kind.extension}"
 
-            # override extension parsed from file...
             if extension != real_extension:
                 if extension:
                     log.warning(f"file extension does not match it's contents: {path}, identified as {real_extension}")
                 else:
                     log.debug(f"file {path} does not have extension, identified by it's contents as {real_extension}")
 
-                # don't do anything if extension is in synonyms
                 if extension not in synonyms_map.get(real_extension, []):
                     extension = real_extension
 

tests/unit/schema/test_mime_types.py

@@ -0,0 +1,51 @@
+import unittest
+import tempfile
+import os
+
+from lbry.schema.mime_types import guess_media_type
+
+class MediaTypeTests(unittest.TestCase):
+    def test_guess_media_type_from_path_only(self):
+        kind = guess_media_type('/tmp/test.mkv')
+        self.assertEqual(kind, ('video/x-matroska', 'video'))
+
+    def test_defaults_for_no_extension(self):
+        kind = guess_media_type('/tmp/test')
+        self.assertEqual(kind, ('application/octet-stream', 'binary'))
+
+    def test_defaults_for_unknown_extension(self):
+        kind = guess_media_type('/tmp/test.unk')
+        self.assertEqual(kind, ('application/x-ext-unk', 'binary'))
+
+    def test_spoofed_unknown(self):
+        with tempfile.TemporaryDirectory() as temp_dir:
+            file = os.path.join(temp_dir, 'spoofed_unknown.txt')
+            with open(file, 'wb') as fd:
+                bytes_lz4 = bytearray([0x04,0x22,0x4d,0x18])
+                fd.write(bytes_lz4)
+                fd.close()
+
+            kind = guess_media_type(file)
+            self.assertEqual(kind, ('application/x-ext-lz4', 'binary'))
+
+    def test_spoofed_known(self):
+        with tempfile.TemporaryDirectory() as temp_dir:
+            file = os.path.join(temp_dir, 'spoofed_known.avi')
+            with open(file, 'wb') as fd:
+                bytes_zip = bytearray([0x50,0x4b,0x03,0x06])
+                fd.write(bytes_zip)
+                fd.close()
+
+            kind = guess_media_type(file)
+            self.assertEqual(kind, ('application/zip', 'binary'))
+
+    def test_spoofed_synonym(self):
+        with tempfile.TemporaryDirectory() as temp_dir:
+            file = os.path.join(temp_dir, 'spoofed_known.cbz')
+            with open(file, 'wb') as fd:
+                bytes_zip = bytearray([0x50,0x4b,0x03,0x06])
+                fd.write(bytes_zip)
+                fd.close()
+
+            kind = guess_media_type(file)
+            self.assertEqual(kind, ('application/vnd.comicbook+zip', 'document'))