Add test of the debug output when reading/writing data

1 files changed, 11 insertions, 1 deletions

diff --git a/tests/coveragetest.py b/tests/coveragetest.py
index 2f488616..a8535418 100644
--- a/tests/coveragetest.py
+++ b/tests/coveragetest.py
@@ -12,7 +12,7 @@ import sys
 import coverage
 from coverage.backunittest import TestCase
 from coverage.backward import StringIO, import_local_file, string_class
-from coverage.debug import _TEST_NAME_FILE
+from coverage.debug import _TEST_NAME_FILE, DebugControl
 from coverage.test_helpers import (
     EnvironmentAwareMixin, StdStreamCapturingMixin, TempDirMixin,
 )
@@ -373,3 +373,13 @@ class CoverageTest(
     def last_line_squeezed(self, report):
         """Return the last line of `report` with the spaces squeezed down."""
         return self.squeezed_lines(report)[-1]
+
+
+class DebugControlString(DebugControl):
+    """A `DebugControl` that writes to a StringIO, for testing."""
+    def __init__(self, options):
+        super(DebugControlString, self).__init__(options, StringIO())
+
+    def get_output(self):
+        """Get the output text from the `DebugControl`."""
+        return self.output.getvalue()