Add tests for pickle functionality

tests/io/test_pickle.py

@@ -0,0 +1,60 @@
+import pickle
+import pytest
+
+from bonobo import Bag, PickleReader, PickleWriter, open_fs
+from bonobo.constants import BEGIN, END
+from bonobo.execution.node import NodeExecutionContext
+from bonobo.util.testing import CapturingNodeExecutionContext
+
+
+def test_write_pickled_dict_to_file(tmpdir):
+    fs, filename = open_fs(tmpdir), 'output.pkl'
+
+    writer = PickleWriter(path=filename)
+    context = NodeExecutionContext(writer, services={'fs': fs})
+
+    context.write(BEGIN, Bag({'foo': 'bar'}), Bag({'foo': 'baz', 'ignore': 'this'}), END)
+
+    context.start()
+    context.step()
+    context.step()
+    context.stop()
+
+    assert pickle.loads(fs.open(filename, 'rb').read()) == {'foo': 'bar'}
+
+    with pytest.raises(AttributeError):
+        getattr(context, 'file')
+
+
+def test_read_pickled_list_from_file(tmpdir):
+    fs, filename = open_fs(tmpdir), 'input.pkl'
+    fs.open(filename, 'wb').write(pickle.dumps([
+        ['a', 'b', 'c'], ['a foo', 'b foo', 'c foo'], ['a bar', 'b bar', 'c bar']
+    ]))
+
+    reader = PickleReader(path=filename)
+
+    context = CapturingNodeExecutionContext(reader, services={'fs': fs})
+
+    context.start()
+    context.write(BEGIN, Bag(), END)
+    context.step()
+    context.stop()
+
+    assert len(context.send.mock_calls) == 2
+
+    args0, kwargs0 = context.send.call_args_list[0]
+    assert len(args0) == 1 and not len(kwargs0)
+    args1, kwargs1 = context.send.call_args_list[1]
+    assert len(args1) == 1 and not len(kwargs1)
+
+    assert args0[0].args[0] == {
+        'a': 'a foo',
+        'b': 'b foo',
+        'c': 'c foo',
+    }
+    assert args1[0].args[0] == {
+        'a': 'a bar',
+        'b': 'b bar',
+        'c': 'c bar',
+    }