add functions to write_catalog (#101)

Author: Kyle Allan

singer/catalog.py

@@ -10,6 +10,13 @@
 LOGGER = get_logger()
 
 
+def write_catalog(catalog):
+    # If the catalog has no streams, log a warning
+    if not catalog.streams:
+        LOGGER.warning("Catalog being written with no streams.")
+
+    json.dump(catalog.to_dict(), sys.stdout, indent=2)
+
 # pylint: disable=too-many-instance-attributes
 class CatalogEntry():
 

tests/test_catalog.py

@@ -1,7 +1,16 @@
 import unittest
 
 from singer.schema import Schema
-from singer.catalog import Catalog, CatalogEntry
+from singer.catalog import Catalog, CatalogEntry, write_catalog
+
+class TestWriteCatalog(unittest.TestCase):
+    def test_write_empty_catalog(self):
+        catalog = Catalog([])
+        write_catalog(catalog)
+
+    def test_write_catalog_with_streams(self):
+        catalog = Catalog([CatalogEntry(tap_stream_id='a',schema=Schema(),metadata=[])])
+        write_catalog(catalog)
 
 class TestGetSelectedStreams(unittest.TestCase):
     def test_one_selected_stream(self):