Fix JsonfileArchiveProcessor:

Rename to `JsonfileArchiver`
Add tests

tests/test_jsonfile_archiver.py

@@ -0,0 +1,48 @@
+import json
+from pytchat.processors.jsonfile_archiver import JsonfileArchiver
+from unittest.mock import patch, mock_open
+from tests.testdata.jsonfile_archiver.chat_component import chat_component
+
+def _open_file(path):
+    with open(path,mode ='r',encoding = 'utf-8') as f:
+        return f.read()
+
+def test_checkpath(mocker):
+    processor = JsonfileArchiver("path")
+    mocker.patch('os.path.exists').side_effect = exists_file
+    '''Test no duplicate file.'''
+    assert processor._checkpath("z:/other.txt") == "z:/other.txt"
+    
+    '''Test duplicate filename. 
+    The case the name first renamed ('test.txt -> test(0).txt')
+    is also duplicated.
+    '''
+    assert processor._checkpath("z:/test.txt") == "z:/test(1).txt"
+    
+    '''Test no extention file (duplicate).'''
+    assert processor._checkpath("z:/test") == "z:/test(0)"
+
+
+def test_read_write():
+    '''Test read and write chatdata'''
+    mock = mock_open(read_data = "")
+    with patch('builtins.open',mock):
+        processor = JsonfileArchiver("path")
+        save_path = processor.process([chat_component])
+    fh = mock()
+    actuals = [args[0] for (args, kwargs) in fh.writelines.call_args_list]
+    '''write format is json dump string  with 0x0A'''
+    to_be_written = [json.dumps(action, ensure_ascii=False)+'\n' 
+        for action in chat_component["chatdata"]]
+    for i in range(len(actuals)):
+        assert actuals[i] == to_be_written[i]
+    assert save_path == {'save_path': 'path', 'total_lines': 7}    
+
+
+def exists_file(path):
+    if path == "z:/test.txt":
+        return True
+    if path == "z:/test(0).txt":
+        return True
+    if path == "z:/test":
+        return True