Add content-type filter method to folder_paths (#4054)

* Add content-type filter method to folder_paths

* Add unit tests

* Hardcode webp content-type

* Annotate content_types as Literal["image", "video", "audio"]

tests-unit/folder_paths_test/filter_by_content_types_test.py

@@ -0,0 +1,52 @@
+import pytest
+import os
+import tempfile
+from folder_paths import filter_files_content_types
+
+@pytest.fixture(scope="module")
+def file_extensions():
+    return {
+        'image': ['bmp', 'cdr', 'gif', 'heif', 'ico', 'jpeg', 'jpg', 'pcx', 'png', 'pnm', 'ppm', 'psd', 'sgi', 'svg', 'tiff', 'webp', 'xbm', 'xcf', 'xpm'], 
+        'audio': ['aif', 'aifc', 'aiff', 'au', 'awb', 'flac', 'm4a', 'mp2', 'mp3', 'ogg', 'sd2', 'smp', 'snd', 'wav'], 
+        'video': ['avi', 'flv', 'm2v', 'm4v', 'mj2', 'mkv', 'mov', 'mp4', 'mpeg', 'mpg', 'ogv', 'qt', 'webm', 'wmv']
+    }
+
+
+@pytest.fixture(scope="module")
+def mock_dir(file_extensions):
+    with tempfile.TemporaryDirectory() as directory:
+        for content_type, extensions in file_extensions.items():
+            for extension in extensions:
+                with open(f"{directory}/sample_{content_type}.{extension}", "w") as f:
+                    f.write(f"Sample {content_type} file in {extension} format")
+        yield directory
+
+
+def test_categorizes_all_correctly(mock_dir, file_extensions):
+    files = os.listdir(mock_dir)
+    for content_type, extensions in file_extensions.items():
+        filtered_files = filter_files_content_types(files, [content_type])
+        for extension in extensions:
+            assert f"sample_{content_type}.{extension}" in filtered_files
+
+
+def test_categorizes_all_uniquely(mock_dir, file_extensions):
+    files = os.listdir(mock_dir)
+    for content_type, extensions in file_extensions.items():
+        filtered_files = filter_files_content_types(files, [content_type])
+        assert len(filtered_files) == len(extensions)
+
+
+def test_handles_bad_extensions():
+    files = ["file1.txt", "file2.py", "file3.example", "file4.pdf", "file5.ini", "file6.doc", "file7.md"]
+    assert filter_files_content_types(files, ["image", "audio", "video"]) == []
+
+
+def test_handles_no_extension():
+    files = ["file1", "file2", "file3", "file4", "file5", "file6", "file7"]
+    assert filter_files_content_types(files, ["image", "audio", "video"]) == []
+
+
+def test_handles_no_files():
+    files = []
+    assert filter_files_content_types(files, ["image", "audio", "video"]) == []