Add io and formatter options to console exporter (open-telemetry#412)

Co-authored-by: Diego Hurtado <[email protected]>

opentelemetry-sdk/src/opentelemetry/sdk/trace/export/__init__.py

@@ -14,6 +14,7 @@
 
 import collections
 import logging
+import sys
 import threading
 import typing
 from enum import Enum
@@ -266,7 +267,15 @@ class ConsoleSpanExporter(SpanExporter):
  spans to the console STDOUT.
  """
 
+ def __init__(
+ self,
+ out: typing.IO = sys.stdout,
+ formatter: typing.Callable[[Span], str] = str,
+ ):
+ self.out = out
+ self.formatter = formatter
+
  def export(self, spans: typing.Sequence[Span]) -> SpanExportResult:
  for span in spans:
- print(span)
+ self.out.write(self.formatter(span))
  return SpanExportResult.SUCCESS

opentelemetry-sdk/tests/trace/export/test_export.py

@@ -276,3 +276,31 @@ def test_batch_span_processor_parameters(self):
  max_queue_size=256,
  max_export_batch_size=512,
  )
+
+
+class TestConsoleSpanExporter(unittest.TestCase):
+ def test_export(self): # pylint: disable=no-self-use
+ """Check that the console exporter prints spans."""
+ exporter = export.ConsoleSpanExporter()
+
+ # Mocking stdout interferes with debugging and test reporting, mock on
+ # the exporter instance instead.
+ span = trace.Span("span name", mock.Mock())
+ with mock.patch.object(exporter, "out") as mock_stdout:
+ exporter.export([span])
+ mock_stdout.write.assert_called_once_with(str(span))
+ self.assertEqual(mock_stdout.write.call_count, 1)
+
+ def test_export_custom(self): # pylint: disable=no-self-use
+ """Check that console exporter uses custom io, formatter."""
+ mock_span_str = mock.Mock(str)
+
+ def formatter(span): # pylint: disable=unused-argument
+ return mock_span_str
+
+ mock_stdout = mock.Mock()
+ exporter = export.ConsoleSpanExporter(
+ out=mock_stdout, formatter=formatter
+ )
+ exporter.export([trace.Span("span name", mock.Mock())])
+ mock_stdout.write.assert_called_once_with(mock_span_str)