Be more lenient to stream=None being passed into TestResult classes

Subtle regression from 2.8.0, which added verbosity support

Author: jelmer

NEWS

@@ -17,6 +17,11 @@ Improvements
 * Support binary contents in ``FileContains`` matcher.
   (Jelmer Vernooij, #538)
 
+* Allow stream=None to be passed to various TestResult
+  classes that now support verbosity; fixes a regression
+from 2.8.0.
+  (Jelmer Vernooij)
+
 2.8.1
 ~~~~~
 

tests/test_testresult.py

@@ -2078,6 +2078,65 @@ def run_tests():
             ),
         )
 
+    def test_none_stream_is_accepted(self):
+        """TextTestResult should accept None as stream for backward compatibility."""
+        result = TextTestResult(None)
+        test = make_test()
+        # Should not raise AttributeError
+        result.startTestRun()
+        result.startTest(test)
+        result.addSuccess(test)
+        result.stopTest(test)
+        result.stopTestRun()
+
+    def test_none_stream_with_failure(self):
+        """TextTestResult with None stream should handle failures."""
+        result = TextTestResult(None)
+        test = make_failing_test()
+        # Should not raise AttributeError
+        test.run(result)
+        self.assertEqual(1, len(result.failures))
+
+    def test_verbosity_zero_produces_no_output(self):
+        """TextTestResult with verbosity=0 should produce no per-test output."""
+        stream = io.StringIO()
+        result = TextTestResult(stream, verbosity=0)
+        test = make_test()
+        result.startTestRun()
+        result.startTest(test)
+        result.addSuccess(test)
+        result.stopTest(test)
+        # Get output up to stopTestRun (which still outputs summary)
+        output_before_stop = stream.getvalue()
+        # Should only have "Tests running...\n" from startTestRun
+        self.assertEqual("Tests running...\n", output_before_stop)
+
+    def test_verbosity_zero_allows_subclass_control(self):
+        """Subclasses can use verbosity=0 to control their own output."""
+
+        class CustomResult(TextTestResult):
+            def __init__(self, stream):
+                super().__init__(stream, verbosity=0)
+
+            def addSuccess(self, test, details=None):
+                super().addSuccess(test, details)
+                self.stream.write("CUSTOM_SUCCESS_MARKER\n")
+
+        stream = io.StringIO()
+        result = CustomResult(stream)
+        test = make_test()
+        result.startTestRun()
+        result.startTest(test)
+        result.addSuccess(test)
+        result.stopTest(test)
+        output = stream.getvalue()
+        # Should have custom output but not parent's dot or "ok"
+        self.assertIn("CUSTOM_SUCCESS_MARKER\n", output)
+        self.assertNotIn("ok\n", output)
+        # Count dots - "Tests running..." has 3 dots, should not have a 4th
+        # from the success indicator
+        self.assertEqual(output.count("."), 3)
+
 
 class TestThreadSafeForwardingResult(TestCase):
     """Tests for `TestThreadSafeForwardingResult`."""

testtools/testresult/real.py

@@ -1244,6 +1244,8 @@ def _delta_to_float(self, a_timedelta, precision):
         )
 
     def _show_list(self, label, error_list):
+        if self.stream is None:
+            return
         for test, output in error_list:
             self.stream.write(self.sep1)
             self.stream.write(f"{label}: {test.id()}\n")
@@ -1252,69 +1254,76 @@ def _show_list(self, label, error_list):
 
     def startTest(self, test):
         super().startTest(test)
-        if self.verbosity >= 2:
+        if self.stream is not None and self.verbosity >= 2:
             self.stream.write(f"{test.id()} ... ")
             self.stream.flush()
 
     def addSuccess(self, test, details=None):
         super().addSuccess(test, details=details)
-        if self.verbosity == 1:
-            self.stream.write(".")
-            self.stream.flush()
-            self._progress_printed = True
-        elif self.verbosity >= 2:
-            self.stream.write("ok\n")
-            self.stream.flush()
+        if self.stream is not None:
+            if self.verbosity == 1:
+                self.stream.write(".")
+                self.stream.flush()
+                self._progress_printed = True
+            elif self.verbosity >= 2:
+                self.stream.write("ok\n")
+                self.stream.flush()
 
     def addError(self, test, err=None, details=None):
         super().addError(test, err=err, details=details)
-        if self.verbosity == 1:
-            self.stream.write("E")
-            self.stream.flush()
-        elif self.verbosity >= 2:
-            self.stream.write("ERROR\n")
-            self.stream.flush()
+        if self.stream is not None:
+            if self.verbosity == 1:
+                self.stream.write("E")
+                self.stream.flush()
+            elif self.verbosity >= 2:
+                self.stream.write("ERROR\n")
+                self.stream.flush()
 
     def addFailure(self, test, err=None, details=None):
         super().addFailure(test, err=err, details=details)
-        if self.verbosity == 1:
-            self.stream.write("F")
-            self.stream.flush()
-        elif self.verbosity >= 2:
-            self.stream.write("FAIL\n")
-            self.stream.flush()
+        if self.stream is not None:
+            if self.verbosity == 1:
+                self.stream.write("F")
+                self.stream.flush()
+            elif self.verbosity >= 2:
+                self.stream.write("FAIL\n")
+                self.stream.flush()
 
     def addSkip(self, test, reason=None, details=None):
         super().addSkip(test, reason=reason, details=details)
-        if self.verbosity == 1:
-            self.stream.write("s")
-            self.stream.flush()
-        elif self.verbosity >= 2:
-            self.stream.write(f"skipped {reason!r}\n")
-            self.stream.flush()
+        if self.stream is not None:
+            if self.verbosity == 1:
+                self.stream.write("s")
+                self.stream.flush()
+            elif self.verbosity >= 2:
+                self.stream.write(f"skipped {reason!r}\n")
+                self.stream.flush()
 
     def addExpectedFailure(self, test, err=None, details=None):
         super().addExpectedFailure(test, err=err, details=details)
-        if self.verbosity == 1:
-            self.stream.write("x")
-            self.stream.flush()
-        elif self.verbosity >= 2:
-            self.stream.write("expected failure\n")
-            self.stream.flush()
+        if self.stream is not None:
+            if self.verbosity == 1:
+                self.stream.write("x")
+                self.stream.flush()
+            elif self.verbosity >= 2:
+                self.stream.write("expected failure\n")
+                self.stream.flush()
 
     def addUnexpectedSuccess(self, test, details=None):
         super().addUnexpectedSuccess(test, details=details)
-        if self.verbosity == 1:
-            self.stream.write("u")
-            self.stream.flush()
-        elif self.verbosity >= 2:
-            self.stream.write("unexpected success\n")
-            self.stream.flush()
+        if self.stream is not None:
+            if self.verbosity == 1:
+                self.stream.write("u")
+                self.stream.flush()
+            elif self.verbosity >= 2:
+                self.stream.write("unexpected success\n")
+                self.stream.flush()
 
     def startTestRun(self):
         super().startTestRun()
         self.__start = self._now()
-        self.stream.write("Tests running...\n")
+        if self.stream is not None:
+            self.stream.write("Tests running...\n")
 
     def stopTestRun(self):
         if self.testsRun != 1:
@@ -1324,31 +1333,33 @@ def stopTestRun(self):
         stop = self._now()
         self._show_list("ERROR", self.errors)
         self._show_list("FAIL", self.failures)
-        for test in self.unexpectedSuccesses:
+        if self.stream is not None:
+            for test in self.unexpectedSuccesses:
+                self.stream.write(
+                    f"{self.sep1}UNEXPECTED SUCCESS: {test.id()}\n{self.sep2}"
+                )
+            # Add newline(s) before summary
+            # If we printed progress indicators (dots), add extra newline
+            if self._progress_printed:
+                self.stream.write("\n\n")
+            else:
+                self.stream.write("\n")
             self.stream.write(
-                f"{self.sep1}UNEXPECTED SUCCESS: {test.id()}\n{self.sep2}"
-            )
-        # Add newline(s) before summary
-        # If we printed progress indicators (dots), add extra newline
-        if self._progress_printed:
-            self.stream.write("\n\n")
-        else:
-            self.stream.write("\n")
-        self.stream.write(
-            f"Ran {self.testsRun} test{plural} in "
-            f"{self._delta_to_float(stop - self.__start, 3):.3f}s\n"
-        )
-        if self.wasSuccessful():
-            self.stream.write("OK\n")
-        else:
-            self.stream.write("FAILED (")
-            details = []
-            failure_count = sum(
-                len(x) for x in (self.failures, self.errors, self.unexpectedSuccesses)
+                f"Ran {self.testsRun} test{plural} in "
+                f"{self._delta_to_float(stop - self.__start, 3):.3f}s\n"
             )
-            details.append(f"failures={failure_count}")
-            self.stream.write(", ".join(details))
-            self.stream.write(")\n")
+            if self.wasSuccessful():
+                self.stream.write("OK\n")
+            else:
+                self.stream.write("FAILED (")
+                details = []
+                failure_count = sum(
+                    len(x)
+                    for x in (self.failures, self.errors, self.unexpectedSuccesses)
+                )
+                details.append(f"failures={failure_count}")
+                self.stream.write(", ".join(details))
+                self.stream.write(")\n")
         super().stopTestRun()