Implements naive csv reader / writer (#2)

tests/io/test_csv.py

@@ -0,0 +1,65 @@
+import pytest
+
+from bonobo import Bag
+from bonobo.core.contexts import ComponentExecutionContext
+from bonobo.io.csv import CsvReader, CsvWriter
+from bonobo.util.testing import CapturingComponentExecutionContext
+from bonobo.util.tokens import BEGIN, END
+
+
+def test_write_csv_to_file(tmpdir):
+    file = tmpdir.join('output.json')
+    writer = CsvWriter(str(file))
+    context = ComponentExecutionContext(writer, None)
+
+    context.initialize()
+    context.recv(BEGIN, Bag({'foo': 'bar'}), Bag({'foo': 'baz', 'ignore': 'this'}), END)
+    context.step()
+    context.step()
+    context.finalize()
+
+    assert file.read() == 'foo\nbar\nbaz\n'
+
+    with pytest.raises(AttributeError):
+        getattr(context, 'file')
+
+
+def test_write_json_without_initializer_should_not_work(tmpdir):
+    file = tmpdir.join('output.json')
+    writer = CsvWriter(str(file))
+
+    context = ComponentExecutionContext(writer, None)
+    with pytest.raises(AttributeError):
+        writer(context, {'foo': 'bar'})
+
+
+def test_read_csv_from_file(tmpdir):
+    file = tmpdir.join('input.csv')
+    file.write('a,b,c\na foo,b foo,c foo\na bar,b bar,c bar')
+
+    reader = CsvReader(str(file), delimiter=',')
+
+    context = CapturingComponentExecutionContext(reader, None)
+
+    context.initialize()
+    context.recv(BEGIN, Bag(), END)
+    context.step()
+    context.finalize()
+
+    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',
+    }