Adds a plugin to dump raw RPC calls to a JSON file (#57)

Author: ESultanik

etheno/jsonrpc.py

@@ -0,0 +1,32 @@
+import json
+from typing import TextIO, Union
+
+from .etheno import EthenoPlugin
+
+class JSONRPCExportPlugin(EthenoPlugin):
+    def __init__(self, out_stream: Union[str, TextIO]):
+        self._was_path = isinstance(out_stream, str)
+        if self._was_path:
+            self._output = open(out_stream, 'w', encoding='utf8')
+        else:
+            self._output = out_stream
+        self._output.write('[')
+        self._count = 0
+
+    def before_post(self, post_data):
+        if self._count > 0:
+            self._output.write(',')
+        self._count += 1
+        self._output.write('\n')
+        json.dump(post_data, self._output)
+        self._output.flush()
+
+    def finalize(self):
+        if self._count:
+            self._output.write('\n')
+        self._output.write(']')
+        self._output.flush()
+        if self._was_path:
+            self._output.close()
+        if hasattr(self._output, 'name'):
+            self.logger.info(f'Raw JSON RPC messages dumped to {self._output.name}')