Support line-delimited JSON

New nodes for handling line-delimited JSON.

https://en.wikipedia.org/wiki/JSON_Streaming

tests/io/test_json.py

@@ -1,8 +1,9 @@
 import pytest
 
 from bonobo import JsonReader, JsonWriter, settings
+from bonobo import LdjsonReader, LdjsonWriter
 from bonobo.execution.node import NodeExecutionContext
-from bonobo.util.testing import FilesystemTester
+from bonobo.util.testing import FilesystemTester, BufferingNodeExecutionContext
 
 json_tester = FilesystemTester('json')
 json_tester.input_data = '''[{"x": "foo"},{"x": "bar"}]'''
@@ -32,3 +33,32 @@ def test_write_json_kwargs(tmpdir, add_kwargs):
 
     with fs.open(filename) as fp:
         assert fp.read() == '[{"foo": "bar"}]'
+
+
+stream_json_tester = FilesystemTester('json')
+stream_json_tester.input_data = '''{"foo": "bar"}\n{"baz": "boz"}'''
+
+
+def test_read_stream_json(tmpdir):
+    fs, filename, services = stream_json_tester.get_services_for_reader(tmpdir)
+    with BufferingNodeExecutionContext(LdjsonReader(filename),
+                                       services=services) as context:
+        context.write_sync(tuple())
+        actual = context.get_buffer()
+
+    expected = [{"foo": "bar"}, {"baz": "boz"}]
+    assert expected == actual
+
+
+def test_write_stream_json(tmpdir):
+    fs, filename, services = stream_json_tester.get_services_for_reader(tmpdir)
+
+    with BufferingNodeExecutionContext(LdjsonWriter(filename),
+                                       services=services) as context:
+        context.write_sync({'foo': 'bar'})
+        context.write_sync({'baz': 'boz'})
+
+    expected = '''{"foo": "bar"}\n{"baz": "boz"}\n'''
+    with fs.open(filename) as fin:
+        actual = fin.read()
+    assert expected == actual