From 13139ec2b2db235090f67ca0d9057e6bc9075f55 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Mon, 30 Dec 2024 06:52:50 +0530
Subject: [PATCH 01/34] Improve error message when forced fail test fails

---
 mutmut/__main__.py     |  8 +++---
 tests/test_mutation.py | 60 +++++++++++++++++++++++++++++++++++++++++-
 2 files changed, 63 insertions(+), 5 deletions(-)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index f9097da6..a8f43e3d 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -885,14 +885,14 @@ def print_stats(source_file_mutation_data_by_path, force_output=False):
     print_status(f'{(s.total - s.not_checked)}/{s.total}  🎉 {s.killed} 🫥 {s.no_tests}  ⏰ {s.timeout}  🤔 {s.suspicious}  🙁 {s.survived}  🔇 {s.skipped}', force_output=force_output)
 
 
-def run_forced_fail(runner):
+def run_forced_fail_test(runner):
     os.environ['MUTANT_UNDER_TEST'] = 'fail'
     with CatchOutput(spinner_title='Running forced fail test') as catcher:
         try:
             if runner.run_forced_fail() == 0:
                 catcher.dump_output()
-                print("FAILED")
-                os._exit(1)
+                print("Error: Unable to force a test failure during the forced fail test")
+                raise SystemExit(1)
         except MutmutProgrammaticFailException:
             pass
     os.environ['MUTANT_UNDER_TEST'] = ''
@@ -1254,7 +1254,7 @@ def run(mutant_names, *, max_children):
     print('    done')
 
     # this can't be the first thing, because it can fail deep inside pytest/django setup and then everything is destroyed
-    run_forced_fail(runner)
+    run_forced_fail_test(runner)
 
     runner.prepare_main_test_run()
 
diff --git a/tests/test_mutation.py b/tests/test_mutation.py
index 3abc6fb5..4d7ca2cd 100644
--- a/tests/test_mutation.py
+++ b/tests/test_mutation.py
@@ -1,8 +1,11 @@
+import os
 from io import StringIO
+from unittest.mock import Mock
 
 import pytest
 from parso import parse
 
+import mutmut
 from mutmut.__main__ import (
     CLASS_NAME_SEPARATOR,
     FuncContext,
@@ -13,7 +16,7 @@
     pragma_no_mutate_lines,
     write_all_mutants_to_file,
     yield_mutants_for_module,
-    yield_mutants_for_node,
+    yield_mutants_for_node, run_forced_fail_test, Config, MutmutProgrammaticFailException,
 )
 
 
@@ -407,3 +410,58 @@ def bar():
 #
 #     mutants = mutants_for_source(source)
 #     assert len(mutants) == 1
+
+
+def test_run_forced_fail_test_with_failing_test(capfd):
+    mutmut.config = _default_mutmut_config()
+    runner = _mocked_runner_run_forced_failed(return_value=1)
+
+    run_forced_fail_test(runner)
+
+    out, err = capfd.readouterr()
+    assert 'Running forced fail test' in out
+    assert 'done' in out
+    assert os.environ['MUTANT_UNDER_TEST'] is ''
+
+
+def test_run_forced_fail_test_with_mutmut_programmatic_fail_exception(capfd):
+    mutmut.config = _default_mutmut_config()
+    runner = _mocked_runner_run_forced_failed(side_effect=MutmutProgrammaticFailException())
+
+    run_forced_fail_test(runner)
+
+    out, err = capfd.readouterr()
+    assert 'Running forced fail test' in out
+    assert 'done' in out
+    assert os.environ['MUTANT_UNDER_TEST'] is ''
+
+
+def test_run_forced_fail_test_with_all_tests_passing(capfd):
+    mutmut.config = _default_mutmut_config()
+    runner = _mocked_runner_run_forced_failed(return_value=0)
+
+    with pytest.raises(SystemExit) as error:
+        run_forced_fail_test(runner)
+
+    assert error.value.code is 1
+    out, err = capfd.readouterr()
+    assert 'Running forced fail test' in out
+    assert 'Error: Unable to force a test failure during the forced fail test' in out
+
+
+def _default_mutmut_config():
+    return Config(
+        do_not_mutate=[],
+        also_copy=[],
+        max_stack_depth=-1,
+        debug=False,
+        paths_to_mutate=[]
+    )
+
+def _mocked_runner_run_forced_failed(return_value=None, side_effect=None):
+    runner = Mock()
+    runner.run_forced_fail = Mock(
+        return_value=return_value,
+        side_effect=side_effect
+    )
+    return runner

From 587f7d3e27bfd4756cea23c508ed3572c09ed5e7 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Mon, 30 Dec 2024 13:31:06 +0530
Subject: [PATCH 02/34] Update error message with suggestion

---
 mutmut/__main__.py     | 2 +-
 tests/test_mutation.py | 2 +-
 2 files changed, 2 insertions(+), 2 deletions(-)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index a8f43e3d..e7ccab3e 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -891,7 +891,7 @@ def run_forced_fail_test(runner):
         try:
             if runner.run_forced_fail() == 0:
                 catcher.dump_output()
-                print("Error: Unable to force a test failure during the forced fail test")
+                print("FAILED: Unable to force test failures")
                 raise SystemExit(1)
         except MutmutProgrammaticFailException:
             pass
diff --git a/tests/test_mutation.py b/tests/test_mutation.py
index 4d7ca2cd..ef327b03 100644
--- a/tests/test_mutation.py
+++ b/tests/test_mutation.py
@@ -446,7 +446,7 @@ def test_run_forced_fail_test_with_all_tests_passing(capfd):
     assert error.value.code is 1
     out, err = capfd.readouterr()
     assert 'Running forced fail test' in out
-    assert 'Error: Unable to force a test failure during the forced fail test' in out
+    assert 'FAILED: Unable to force test failures' in out
 
 
 def _default_mutmut_config():

From 70cbf8025d308d60268449e5fb7240c394bfee65 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Tue, 31 Dec 2024 16:37:58 +0530
Subject: [PATCH 03/34] Add some sleeps and debug output to rule out race
 condition for GitHub Actions test failure

---
 mutmut/__main__.py     |  3 ++-
 tests/test_mutation.py | 16 ++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index e7ccab3e..920d762c 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -891,7 +891,8 @@ def run_forced_fail_test(runner):
         try:
             if runner.run_forced_fail() == 0:
                 catcher.dump_output()
-                print("FAILED: Unable to force test failures")
+                print("\nFAILED: Unable to force test failures")
+                sleep(2)
                 raise SystemExit(1)
         except MutmutProgrammaticFailException:
             pass
diff --git a/tests/test_mutation.py b/tests/test_mutation.py
index ef327b03..681fd04a 100644
--- a/tests/test_mutation.py
+++ b/tests/test_mutation.py
@@ -1,5 +1,6 @@
 import os
 from io import StringIO
+from time import sleep
 from unittest.mock import Mock
 
 import pytest
@@ -419,6 +420,11 @@ def test_run_forced_fail_test_with_failing_test(capfd):
     run_forced_fail_test(runner)
 
     out, err = capfd.readouterr()
+    print(f"out: {out}")
+    print(f"err: {err}")
+    sleep(2)
+    print(f"out: {out}")
+    print(f"err: {err}")
     assert 'Running forced fail test' in out
     assert 'done' in out
     assert os.environ['MUTANT_UNDER_TEST'] is ''
@@ -431,6 +437,11 @@ def test_run_forced_fail_test_with_mutmut_programmatic_fail_exception(capfd):
     run_forced_fail_test(runner)
 
     out, err = capfd.readouterr()
+    print(f"out: {out}")
+    print(f"err: {err}")
+    sleep(2)
+    print(f"out: {out}")
+    print(f"err: {err}")
     assert 'Running forced fail test' in out
     assert 'done' in out
     assert os.environ['MUTANT_UNDER_TEST'] is ''
@@ -445,6 +456,11 @@ def test_run_forced_fail_test_with_all_tests_passing(capfd):
 
     assert error.value.code is 1
     out, err = capfd.readouterr()
+    print(f"out: {out}")
+    print(f"err: {err}")
+    sleep(2)
+    print(f"out: {out}")
+    print(f"err: {err}")
     assert 'Running forced fail test' in out
     assert 'FAILED: Unable to force test failures' in out
 

From c08280d1b979648c0924f7d85c73d722c5bd60a8 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Tue, 31 Dec 2024 16:49:54 +0530
Subject: [PATCH 04/34] Try running on MacOS in case that's the difference

---
 .github/workflows/tests.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 02b3def5..0172bd97 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -5,7 +5,7 @@ on: [push, pull_request]
 jobs:
   tests:
     name: Tests
-    runs-on: ubuntu-latest
+    runs-on: macos-14
     steps:
       - name: Checkout
         uses: actions/checkout@v3

From 615f592afecf1986d13e6a90fc64e50661022d4e Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Tue, 31 Dec 2024 16:59:13 +0530
Subject: [PATCH 05/34] Revert "Add some sleeps and debug output to rule out
 race condition for GitHub Actions test failure"

This reverts commit 70cbf8025d308d60268449e5fb7240c394bfee65.
---
 mutmut/__main__.py     |  3 +--
 tests/test_mutation.py | 16 ----------------
 2 files changed, 1 insertion(+), 18 deletions(-)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index 920d762c..e7ccab3e 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -891,8 +891,7 @@ def run_forced_fail_test(runner):
         try:
             if runner.run_forced_fail() == 0:
                 catcher.dump_output()
-                print("\nFAILED: Unable to force test failures")
-                sleep(2)
+                print("FAILED: Unable to force test failures")
                 raise SystemExit(1)
         except MutmutProgrammaticFailException:
             pass
diff --git a/tests/test_mutation.py b/tests/test_mutation.py
index 681fd04a..ef327b03 100644
--- a/tests/test_mutation.py
+++ b/tests/test_mutation.py
@@ -1,6 +1,5 @@
 import os
 from io import StringIO
-from time import sleep
 from unittest.mock import Mock
 
 import pytest
@@ -420,11 +419,6 @@ def test_run_forced_fail_test_with_failing_test(capfd):
     run_forced_fail_test(runner)
 
     out, err = capfd.readouterr()
-    print(f"out: {out}")
-    print(f"err: {err}")
-    sleep(2)
-    print(f"out: {out}")
-    print(f"err: {err}")
     assert 'Running forced fail test' in out
     assert 'done' in out
     assert os.environ['MUTANT_UNDER_TEST'] is ''
@@ -437,11 +431,6 @@ def test_run_forced_fail_test_with_mutmut_programmatic_fail_exception(capfd):
     run_forced_fail_test(runner)
 
     out, err = capfd.readouterr()
-    print(f"out: {out}")
-    print(f"err: {err}")
-    sleep(2)
-    print(f"out: {out}")
-    print(f"err: {err}")
     assert 'Running forced fail test' in out
     assert 'done' in out
     assert os.environ['MUTANT_UNDER_TEST'] is ''
@@ -456,11 +445,6 @@ def test_run_forced_fail_test_with_all_tests_passing(capfd):
 
     assert error.value.code is 1
     out, err = capfd.readouterr()
-    print(f"out: {out}")
-    print(f"err: {err}")
-    sleep(2)
-    print(f"out: {out}")
-    print(f"err: {err}")
     assert 'Running forced fail test' in out
     assert 'FAILED: Unable to force test failures' in out
 

From 2c3113d33e9e77f65b7317a290e9d1bb31972416 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Tue, 31 Dec 2024 16:59:19 +0530
Subject: [PATCH 06/34] Revert "Try running on MacOS in case that's the
 difference"

This reverts commit c08280d1b979648c0924f7d85c73d722c5bd60a8.
---
 .github/workflows/tests.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 0172bd97..02b3def5 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -5,7 +5,7 @@ on: [push, pull_request]
 jobs:
   tests:
     name: Tests
-    runs-on: macos-14
+    runs-on: ubuntu-latest
     steps:
       - name: Checkout
         uses: actions/checkout@v3

From 5c60640e5866eaa670324f29ea9b13e7e11cc65b Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Mon, 13 Jan 2025 07:43:01 +0530
Subject: [PATCH 07/34] Attempt to see actual output in GitHub Actions

---
 .github/workflows/tests.yml |  3 ++-
 tests/test_mutation.py      | 14 ++++++++++++++
 2 files changed, 16 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 41637cf5..190eeb10 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -27,5 +27,6 @@ jobs:
           pip install -r test_requirements.txt
 
       - name: Run tests
-        run: python -m pytest
+        # run: python -m pytest
+        run: python -m pytest -vvv --capture=no tests/test_mutation.py::test_run_forced_fail_test_with_failing_test_TEMP
         continue-on-error: false
diff --git a/tests/test_mutation.py b/tests/test_mutation.py
index ef327b03..837cc0f0 100644
--- a/tests/test_mutation.py
+++ b/tests/test_mutation.py
@@ -412,6 +412,20 @@ def bar():
 #     assert len(mutants) == 1
 
 
+def test_run_forced_fail_test_with_failing_test_TEMP():
+    print("temp_test_run_forced_fail_test_with_failing_test - start")
+    mutmut.config = _default_mutmut_config()
+    runner = _mocked_runner_run_forced_failed(return_value=1)
+
+    run_forced_fail_test(runner)
+
+    # out, err = capfd.readouterr()
+    # assert 'Running forced fail test' in out
+    # assert 'done' in out
+    assert os.environ['MUTANT_UNDER_TEST'] is ''
+    print("temp_test_run_forced_fail_test_with_failing_test - end")
+
+
 def test_run_forced_fail_test_with_failing_test(capfd):
     mutmut.config = _default_mutmut_config()
     runner = _mocked_runner_run_forced_failed(return_value=1)

From 7d7c8b9e0ae0ec85148813abb6a94e0ae38262b0 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Mon, 13 Jan 2025 07:45:16 +0530
Subject: [PATCH 08/34] More GitHub Actions debug output

---
 .github/workflows/tests.yml | 7 ++++++-
 1 file changed, 6 insertions(+), 1 deletion(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 190eeb10..ee117ba7 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -26,7 +26,12 @@ jobs:
           pip install -r requirements.txt
           pip install -r test_requirements.txt
 
-      - name: Run tests
+      - name: Run tests TEMP
         # run: python -m pytest
         run: python -m pytest -vvv --capture=no tests/test_mutation.py::test_run_forced_fail_test_with_failing_test_TEMP
         continue-on-error: false
+
+      - name: Run tests
+        # run: python -m pytest
+        run: python -m pytest -vvv --capture=no tests/test_mutation.py::test_run_forced_fail_test_with_failing_test
+        continue-on-error: false

From 4d3050a5dd6b347ed167cb5f99d0d3857a1e30bc Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Mon, 13 Jan 2025 07:51:37 +0530
Subject: [PATCH 09/34] Clutching at straws

---
 tests/test_mutation.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tests/test_mutation.py b/tests/test_mutation.py
index 837cc0f0..5f175e22 100644
--- a/tests/test_mutation.py
+++ b/tests/test_mutation.py
@@ -432,9 +432,9 @@ def test_run_forced_fail_test_with_failing_test(capfd):
 
     run_forced_fail_test(runner)
 
-    out, err = capfd.readouterr()
-    assert 'Running forced fail test' in out
-    assert 'done' in out
+    captured_output = capfd.readouterr()
+    assert 'Running forced fail test' in captured_output.out
+    assert 'done' in captured_output.out
     assert os.environ['MUTANT_UNDER_TEST'] is ''
 
 

From 66b37057f98f8c0b200e73de4edd8a35b7a3e0ea Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Mon, 13 Jan 2025 07:53:30 +0530
Subject: [PATCH 10/34] Revert "Clutching at straws"

This reverts commit 4d3050a5dd6b347ed167cb5f99d0d3857a1e30bc.
---
 tests/test_mutation.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/tests/test_mutation.py b/tests/test_mutation.py
index 5f175e22..837cc0f0 100644
--- a/tests/test_mutation.py
+++ b/tests/test_mutation.py
@@ -432,9 +432,9 @@ def test_run_forced_fail_test_with_failing_test(capfd):
 
     run_forced_fail_test(runner)
 
-    captured_output = capfd.readouterr()
-    assert 'Running forced fail test' in captured_output.out
-    assert 'done' in captured_output.out
+    out, err = capfd.readouterr()
+    assert 'Running forced fail test' in out
+    assert 'done' in out
     assert os.environ['MUTANT_UNDER_TEST'] is ''
 
 

From 030faa88307263c6db63dfa42c32a5c8eaf15e5f Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Mon, 13 Jan 2025 07:54:49 +0530
Subject: [PATCH 11/34] try a sleep in case it is a race condition

---
 tests/test_mutation.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tests/test_mutation.py b/tests/test_mutation.py
index 837cc0f0..a70d6d95 100644
--- a/tests/test_mutation.py
+++ b/tests/test_mutation.py
@@ -1,5 +1,6 @@
 import os
 from io import StringIO
+from time import sleep
 from unittest.mock import Mock
 
 import pytest
@@ -432,6 +433,8 @@ def test_run_forced_fail_test_with_failing_test(capfd):
 
     run_forced_fail_test(runner)
 
+    sleep(5)
+
     out, err = capfd.readouterr()
     assert 'Running forced fail test' in out
     assert 'done' in out

From ab66e9e668b1de147a75db84b9003205d72fbb27 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Mon, 13 Jan 2025 08:10:06 +0530
Subject: [PATCH 12/34] Revert "try a sleep in case it is a race condition"

This reverts commit 030faa88307263c6db63dfa42c32a5c8eaf15e5f.
---
 tests/test_mutation.py | 3 ---
 1 file changed, 3 deletions(-)

diff --git a/tests/test_mutation.py b/tests/test_mutation.py
index a70d6d95..837cc0f0 100644
--- a/tests/test_mutation.py
+++ b/tests/test_mutation.py
@@ -1,6 +1,5 @@
 import os
 from io import StringIO
-from time import sleep
 from unittest.mock import Mock
 
 import pytest
@@ -433,8 +432,6 @@ def test_run_forced_fail_test_with_failing_test(capfd):
 
     run_forced_fail_test(runner)
 
-    sleep(5)
-
     out, err = capfd.readouterr()
     assert 'Running forced fail test' in out
     assert 'done' in out

From 6fd2e3ba45002ca155b3c27d52561f09734631a1 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Tue, 14 Jan 2025 08:24:19 +0530
Subject: [PATCH 13/34] Debug output for GitHub Actions

---
 mutmut/__main__.py     | 8 ++++++++
 tests/test_mutation.py | 3 +++
 2 files changed, 11 insertions(+)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index ba298f96..334ea1e0 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -906,6 +906,7 @@ def __init__(self, callback=lambda s: None, spinner_title=None):
 
         class StdOutRedirect(TextIOBase):
             def __init__(self, catcher):
+                print("In StdOutRedirect.__init__")
                 self.catcher = catcher
 
             def write(self, s):
@@ -918,27 +919,34 @@ def write(self, s):
 
     # noinspection PyMethodMayBeStatic
     def stop(self):
+        print("In CatchOutput.stop")
         sys.stdout = sys.__stdout__
         sys.stderr = sys.__stderr__
 
     def start(self):
+        print("In CatchOutput.start")
         if self.spinner_title:
             print_status(self.spinner_title)
         sys.stdout = self.redirect
         sys.stderr = self.redirect
         if mutmut.config.debug:
+            print("Stopping because debug")
             self.stop()
 
     def dump_output(self):
+        print("In CatchOutput.dump_output")
+        print(f"self.strings: {self.strings}")
         self.stop()
         for line in self.strings:
             print(line, end='')
 
     def __enter__(self):
+        print("In CatchOutput.__enter__")
         self.start()
         return self
 
     def __exit__(self, exc_type, exc_val, exc_tb):
+        print("In CatchOutput.__exit__")
         self.stop()
         if self.spinner_title:
             print()
diff --git a/tests/test_mutation.py b/tests/test_mutation.py
index 837cc0f0..4cf34743 100644
--- a/tests/test_mutation.py
+++ b/tests/test_mutation.py
@@ -433,6 +433,9 @@ def test_run_forced_fail_test_with_failing_test(capfd):
     run_forced_fail_test(runner)
 
     out, err = capfd.readouterr()
+    with capfd.disabled():
+        print(out)
+        print(err)
     assert 'Running forced fail test' in out
     assert 'done' in out
     assert os.environ['MUTANT_UNDER_TEST'] is ''

From f94b6495a3dc447126f20b961f4a6894039aa003 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Tue, 14 Jan 2025 08:26:52 +0530
Subject: [PATCH 14/34] Debug output for GitHub Actions

---
 tests/test_mutation.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/tests/test_mutation.py b/tests/test_mutation.py
index 4cf34743..574d7de3 100644
--- a/tests/test_mutation.py
+++ b/tests/test_mutation.py
@@ -434,8 +434,8 @@ def test_run_forced_fail_test_with_failing_test(capfd):
 
     out, err = capfd.readouterr()
     with capfd.disabled():
-        print(out)
-        print(err)
+        print(f"out: {out}")
+        print(f"err: {err}")
     assert 'Running forced fail test' in out
     assert 'done' in out
     assert os.environ['MUTANT_UNDER_TEST'] is ''

From 5777f876e9de8adee39cd39e3c997c70dcfd3b94 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Tue, 14 Jan 2025 08:35:42 +0530
Subject: [PATCH 15/34] Try explicit catcher.stop()

---
 mutmut/__main__.py     | 1 +
 tests/test_mutation.py | 1 +
 2 files changed, 2 insertions(+)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index 334ea1e0..90194165 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -895,6 +895,7 @@ def run_forced_fail_test(runner):
                 raise SystemExit(1)
         except MutmutProgrammaticFailException:
             pass
+        catcher.stop()
     os.environ['MUTANT_UNDER_TEST'] = ''
     print('    done')
 
diff --git a/tests/test_mutation.py b/tests/test_mutation.py
index 574d7de3..8c7240e9 100644
--- a/tests/test_mutation.py
+++ b/tests/test_mutation.py
@@ -434,6 +434,7 @@ def test_run_forced_fail_test_with_failing_test(capfd):
 
     out, err = capfd.readouterr()
     with capfd.disabled():
+        print()
         print(f"out: {out}")
         print(f"err: {err}")
     assert 'Running forced fail test' in out

From 009f55b428f1a3beee4dfecb74f177d0f0e098c3 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Tue, 14 Jan 2025 08:37:46 +0530
Subject: [PATCH 16/34] Try with os._exit(1)

---
 mutmut/__main__.py | 5 +++--
 1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index 90194165..327608a2 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -892,10 +892,11 @@ def run_forced_fail_test(runner):
             if runner.run_forced_fail() == 0:
                 catcher.dump_output()
                 print("FAILED: Unable to force test failures")
-                raise SystemExit(1)
+                # raise SystemExit(1)
+                os._exit(1)
         except MutmutProgrammaticFailException:
             pass
-        catcher.stop()
+        # catcher.stop()
     os.environ['MUTANT_UNDER_TEST'] = ''
     print('    done')
 

From 712d279fd8b1730dfb5f2d69e04f9db11b9e910c Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Tue, 14 Jan 2025 08:43:00 +0530
Subject: [PATCH 17/34] Move the done into the with CatchOutput block

---
 mutmut/__main__.py | 4 +++-
 1 file changed, 3 insertions(+), 1 deletion(-)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index 327608a2..0b6f2d19 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -897,8 +897,10 @@ def run_forced_fail_test(runner):
         except MutmutProgrammaticFailException:
             pass
         # catcher.stop()
+        print('    done - a')
+
     os.environ['MUTANT_UNDER_TEST'] = ''
-    print('    done')
+    print('    done - b')
 
 
 class CatchOutput:

From c2f57abc2f1bebfbba2bc88072d264cf22705145 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Tue, 14 Jan 2025 08:44:30 +0530
Subject: [PATCH 18/34] Try done output in the except block

---
 mutmut/__main__.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index 0b6f2d19..f88ab785 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -895,6 +895,7 @@ def run_forced_fail_test(runner):
                 # raise SystemExit(1)
                 os._exit(1)
         except MutmutProgrammaticFailException:
+            print('    done - c')
             pass
         # catcher.stop()
         print('    done - a')

From 7faadf9a3484ca37bbff8eaadaa336fee0e61f9a Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Tue, 14 Jan 2025 08:46:50 +0530
Subject: [PATCH 19/34] Try catcher.dump_output()

---
 mutmut/__main__.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index f88ab785..0c4fd02a 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -899,6 +899,7 @@ def run_forced_fail_test(runner):
             pass
         # catcher.stop()
         print('    done - a')
+        catcher.dump_output()
 
     os.environ['MUTANT_UNDER_TEST'] = ''
     print('    done - b')

From d5de126afb9dd2142cbe6a3fd32a75f224d6a5e7 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Tue, 14 Jan 2025 08:47:23 +0530
Subject: [PATCH 20/34] Use SystemExit again

---
 mutmut/__main__.py | 3 +--
 1 file changed, 1 insertion(+), 2 deletions(-)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index 0c4fd02a..77992a16 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -892,8 +892,7 @@ def run_forced_fail_test(runner):
             if runner.run_forced_fail() == 0:
                 catcher.dump_output()
                 print("FAILED: Unable to force test failures")
-                # raise SystemExit(1)
-                os._exit(1)
+                raise SystemExit(1)
         except MutmutProgrammaticFailException:
             print('    done - c')
             pass

From c6ce598b78ae500f2b1aec85eceb3502261bb327 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Tue, 14 Jan 2025 08:52:20 +0530
Subject: [PATCH 21/34] Clutching at straws

---
 tests/test_mutation.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/tests/test_mutation.py b/tests/test_mutation.py
index 8c7240e9..b9656096 100644
--- a/tests/test_mutation.py
+++ b/tests/test_mutation.py
@@ -437,6 +437,10 @@ def test_run_forced_fail_test_with_failing_test(capfd):
         print()
         print(f"out: {out}")
         print(f"err: {err}")
+
+    print()
+    print(f"out: {out}")
+    print(f"err: {err}")
     assert 'Running forced fail test' in out
     assert 'done' in out
     assert os.environ['MUTANT_UNDER_TEST'] is ''

From 134d502ac4786cf4b418a9854ce2bc329c840b9a Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Tue, 14 Jan 2025 08:53:52 +0530
Subject: [PATCH 22/34] Clutching at straws

---
 tests/test_mutation.py | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/tests/test_mutation.py b/tests/test_mutation.py
index b9656096..b87367ad 100644
--- a/tests/test_mutation.py
+++ b/tests/test_mutation.py
@@ -437,6 +437,9 @@ def test_run_forced_fail_test_with_failing_test(capfd):
         print()
         print(f"out: {out}")
         print(f"err: {err}")
+        assert 'Running forced fail test' in out
+        assert 'done' in out
+        assert os.environ['MUTANT_UNDER_TEST'] is ''
 
     print()
     print(f"out: {out}")

From bb002bc7e7dbbb76201fbc94d464f6699d5c0045 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Wed, 15 Jan 2025 08:22:23 +0530
Subject: [PATCH 23/34] sys.stdout.write

---
 mutmut/__main__.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index 77992a16..9d1e42ee 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -894,14 +894,14 @@ def run_forced_fail_test(runner):
                 print("FAILED: Unable to force test failures")
                 raise SystemExit(1)
         except MutmutProgrammaticFailException:
-            print('    done - c')
+            sys.stdout.write('    done - c')
             pass
         # catcher.stop()
-        print('    done - a')
+        sys.stdout.write('    done - a')
         catcher.dump_output()
 
     os.environ['MUTANT_UNDER_TEST'] = ''
-    print('    done - b')
+    sys.stdout.write('    done - b')
 
 
 class CatchOutput:

From de1020d7827486953a99809799f26d4b54012124 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Wed, 15 Jan 2025 08:26:52 +0530
Subject: [PATCH 24/34] Revert "sys.stdout.write"

This reverts commit bb002bc7e7dbbb76201fbc94d464f6699d5c0045.
---
 mutmut/__main__.py | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index 9d1e42ee..77992a16 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -894,14 +894,14 @@ def run_forced_fail_test(runner):
                 print("FAILED: Unable to force test failures")
                 raise SystemExit(1)
         except MutmutProgrammaticFailException:
-            sys.stdout.write('    done - c')
+            print('    done - c')
             pass
         # catcher.stop()
-        sys.stdout.write('    done - a')
+        print('    done - a')
         catcher.dump_output()
 
     os.environ['MUTANT_UNDER_TEST'] = ''
-    sys.stdout.write('    done - b')
+    print('    done - b')
 
 
 class CatchOutput:

From 39a748f366be56644225ca1012baff8c70b77606 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Wed, 15 Jan 2025 08:30:39 +0530
Subject: [PATCH 25/34] Run on macos-15 in GitHub Actions

---
 .github/workflows/tests.yml | 33 +++++++++++++++++++++++++++++++++
 1 file changed, 33 insertions(+)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index ee117ba7..b8c3beee 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -35,3 +35,36 @@ jobs:
         # run: python -m pytest
         run: python -m pytest -vvv --capture=no tests/test_mutation.py::test_run_forced_fail_test_with_failing_test
         continue-on-error: false
+
+  tests-mac-os:
+    name: Test Python ${{ matrix.python-version }} on MacOS
+    # Todo: Revert to ubuntu-latest when Python 3.7 support no longer needed
+    runs-on: macos-15
+    strategy:
+      fail-fast: false
+      matrix:
+        python-version: ["3.13", "3.12", "3.11", "3.10", "3.9", "3.8", "3.7"]
+    steps:
+      - name: Checkout
+        uses: actions/checkout@v3
+
+      - name: Set up Python ${{ matrix.python-version }}
+        uses: actions/setup-python@v5
+        with:
+          python-version: ${{ matrix.python-version }}
+
+      - name: Install dependencies
+        run: |
+          python -m pip install --upgrade pip
+          pip install -r requirements.txt
+          pip install -r test_requirements.txt
+
+      - name: Run tests TEMP
+        # run: python -m pytest
+        run: python -m pytest -vvv --capture=no tests/test_mutation.py::test_run_forced_fail_test_with_failing_test_TEMP
+        continue-on-error: false
+
+      - name: Run tests
+        # run: python -m pytest
+        run: python -m pytest -vvv --capture=no tests/test_mutation.py::test_run_forced_fail_test_with_failing_test
+        continue-on-error: false

From 3084a7630279bc1740093a76a141b5e1fb701889 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Wed, 15 Jan 2025 08:37:34 +0530
Subject: [PATCH 26/34] Output some python info

---
 .github/workflows/tests.yml | 8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index b8c3beee..1532db6a 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -20,6 +20,10 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
 
+      - run: python --version
+
+      - run: which python
+
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip
@@ -53,6 +57,10 @@ jobs:
         with:
           python-version: ${{ matrix.python-version }}
 
+      - run: python --version
+
+      - run: which python
+
       - name: Install dependencies
         run: |
           python -m pip install --upgrade pip

From 29add96f6eb074de2b5c47ff5570f63105e37fd5 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Sun, 19 Jan 2025 00:11:01 +0530
Subject: [PATCH 27/34] Revert "Run on macos-15 in GitHub Actions"

This reverts commit 39a748f366be56644225ca1012baff8c70b77606.
---
 .github/workflows/tests.yml | 37 -------------------------------------
 1 file changed, 37 deletions(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 1532db6a..61649265 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -39,40 +39,3 @@ jobs:
         # run: python -m pytest
         run: python -m pytest -vvv --capture=no tests/test_mutation.py::test_run_forced_fail_test_with_failing_test
         continue-on-error: false
-
-  tests-mac-os:
-    name: Test Python ${{ matrix.python-version }} on MacOS
-    # Todo: Revert to ubuntu-latest when Python 3.7 support no longer needed
-    runs-on: macos-15
-    strategy:
-      fail-fast: false
-      matrix:
-        python-version: ["3.13", "3.12", "3.11", "3.10", "3.9", "3.8", "3.7"]
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v3
-
-      - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v5
-        with:
-          python-version: ${{ matrix.python-version }}
-
-      - run: python --version
-
-      - run: which python
-
-      - name: Install dependencies
-        run: |
-          python -m pip install --upgrade pip
-          pip install -r requirements.txt
-          pip install -r test_requirements.txt
-
-      - name: Run tests TEMP
-        # run: python -m pytest
-        run: python -m pytest -vvv --capture=no tests/test_mutation.py::test_run_forced_fail_test_with_failing_test_TEMP
-        continue-on-error: false
-
-      - name: Run tests
-        # run: python -m pytest
-        run: python -m pytest -vvv --capture=no tests/test_mutation.py::test_run_forced_fail_test_with_failing_test
-        continue-on-error: false

From 713e228b806ec85fc7938bcce630510d9d884fa5 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Sun, 19 Jan 2025 00:11:55 +0530
Subject: [PATCH 28/34] setup-python@v4

---
 .github/workflows/tests.yml | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 61649265..e2b36748 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -16,7 +16,7 @@ jobs:
         uses: actions/checkout@v3
 
       - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v5
+        uses: actions/setup-python@v4
         with:
           python-version: ${{ matrix.python-version }}
 

From 8f8c2cd945799f10e641412f79f9bc89fc22ce2f Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Sun, 19 Jan 2025 00:15:22 +0530
Subject: [PATCH 29/34] Drop setup-python@v5

---
 .github/workflows/tests.yml | 12 ++++++------
 1 file changed, 6 insertions(+), 6 deletions(-)

diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index e2b36748..5621e693 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -9,16 +9,16 @@ jobs:
     runs-on: ubuntu-22.04
     strategy:
       fail-fast: false
-      matrix:
-        python-version: ["3.13", "3.12", "3.11", "3.10", "3.9", "3.8", "3.7"]
+      # matrix:
+      #   python-version: ["3.13", "3.12", "3.11", "3.10", "3.9", "3.8", "3.7"]
     steps:
       - name: Checkout
         uses: actions/checkout@v3
 
-      - name: Set up Python ${{ matrix.python-version }}
-        uses: actions/setup-python@v4
-        with:
-          python-version: ${{ matrix.python-version }}
+      # - name: Set up Python ${{ matrix.python-version }}
+      #   uses: actions/setup-python@v5
+      #   with:
+      #     python-version: ${{ matrix.python-version }}
 
       - run: python --version
 

From ac1949122c16f563816884f5c2c1b1efccb484f7 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Sun, 19 Jan 2025 00:20:08 +0530
Subject: [PATCH 30/34] Clutching at straws

---
 mutmut/__main__.py | 4 ++++
 1 file changed, 4 insertions(+)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index 77992a16..350f8353 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -902,6 +902,10 @@ def run_forced_fail_test(runner):
 
     os.environ['MUTANT_UNDER_TEST'] = ''
     print('    done - b')
+    print('111')
+    print('222')
+    print('333')
+    print()
 
 
 class CatchOutput:

From a7ca7d02330b0a6d86ad0617df383d13a674941c Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Sun, 19 Jan 2025 00:23:11 +0530
Subject: [PATCH 31/34] Clutching at straws

---
 mutmut/__main__.py | 1 +
 1 file changed, 1 insertion(+)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index 350f8353..5dc93c9d 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -889,6 +889,7 @@ def run_forced_fail_test(runner):
     os.environ['MUTANT_UNDER_TEST'] = 'fail'
     with CatchOutput(spinner_title='Running forced fail test') as catcher:
         try:
+            print(f"runner.run_forced_fail(): {runner.run_forced_fail()}")
             if runner.run_forced_fail() == 0:
                 catcher.dump_output()
                 print("FAILED: Unable to force test failures")

From 43a4bdd8b491655ecb9f36414967f0ce0fe1e378 Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Sun, 19 Jan 2025 00:27:04 +0530
Subject: [PATCH 32/34] Clutching at straws

---
 mutmut/__main__.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index 5dc93c9d..c9887354 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -891,7 +891,7 @@ def run_forced_fail_test(runner):
         try:
             print(f"runner.run_forced_fail(): {runner.run_forced_fail()}")
             if runner.run_forced_fail() == 0:
-                catcher.dump_output()
+                # catcher.dump_output()
                 print("FAILED: Unable to force test failures")
                 raise SystemExit(1)
         except MutmutProgrammaticFailException:

From a94e680f89d82fa97de80165627f415ad22040fd Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Sun, 19 Jan 2025 00:39:33 +0530
Subject: [PATCH 33/34] Clutching at straws

---
 mutmut/__main__.py | 9 ++++-----
 1 file changed, 4 insertions(+), 5 deletions(-)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index c9887354..c6f5702f 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -644,6 +644,7 @@ def run_stats(self, *, tests):
         raise NotImplementedError()
 
     def run_forced_fail(self):
+        print("In TestRunner.run_forced_fail")
         raise NotImplementedError()
 
     def prepare_main_test_run(self):
@@ -728,6 +729,7 @@ def run_tests(self, *, mutant_name, tests):
             return int(self.execute_pytest(['-x', '-q', '--import-mode=append'] + list(tests)))
 
     def run_forced_fail(self):
+        print("In PytestRunner.run_forced_fail")
         with change_cwd('mutants'):
             return int(self.execute_pytest(['-x', '-q', '--import-mode=append']))
 
@@ -762,6 +764,7 @@ def post_test_callback(_name, **_):
         return hammett.main(quiet=True, fail_fast=True, disable_assert_analyze=True, post_test_callback=post_test_callback, use_cache=False, insert_cwd=False)
 
     def run_forced_fail(self):
+        print("In HammettRunner.run_forced_fail")
         import hammett
         return hammett.main(quiet=True, fail_fast=True, disable_assert_analyze=True, use_cache=False, insert_cwd=False)
 
@@ -899,14 +902,10 @@ def run_forced_fail_test(runner):
             pass
         # catcher.stop()
         print('    done - a')
-        catcher.dump_output()
+        # catcher.dump_output()
 
     os.environ['MUTANT_UNDER_TEST'] = ''
     print('    done - b')
-    print('111')
-    print('222')
-    print('333')
-    print()
 
 
 class CatchOutput:

From af2663abbbd103616a8c1e93efe78b1d6f87576d Mon Sep 17 00:00:00 2001
From: Will Gibson <8738245+WillGibson@users.noreply.github.com>
Date: Sun, 19 Jan 2025 00:43:58 +0530
Subject: [PATCH 34/34] Drop CatchOutput

---
 mutmut/__main__.py | 27 ++++++++++++++-------------
 1 file changed, 14 insertions(+), 13 deletions(-)

diff --git a/mutmut/__main__.py b/mutmut/__main__.py
index c6f5702f..c227d260 100644
--- a/mutmut/__main__.py
+++ b/mutmut/__main__.py
@@ -890,19 +890,20 @@ def print_stats(source_file_mutation_data_by_path, force_output=False):
 
 def run_forced_fail_test(runner):
     os.environ['MUTANT_UNDER_TEST'] = 'fail'
-    with CatchOutput(spinner_title='Running forced fail test') as catcher:
-        try:
-            print(f"runner.run_forced_fail(): {runner.run_forced_fail()}")
-            if runner.run_forced_fail() == 0:
-                # catcher.dump_output()
-                print("FAILED: Unable to force test failures")
-                raise SystemExit(1)
-        except MutmutProgrammaticFailException:
-            print('    done - c')
-            pass
-        # catcher.stop()
-        print('    done - a')
-        # catcher.dump_output()
+    # with CatchOutput(spinner_title='Running forced fail test') as catcher:
+    print("'Running forced fail test'")
+    try:
+        print(f"runner.run_forced_fail(): {runner.run_forced_fail()}")
+        if runner.run_forced_fail() == 0:
+            # catcher.dump_output()
+            print("FAILED: Unable to force test failures")
+            raise SystemExit(1)
+    except MutmutProgrammaticFailException:
+        print('    done - c')
+        pass
+    # catcher.stop()
+    print('    done - a')
+    # catcher.dump_output()
 
     os.environ['MUTANT_UNDER_TEST'] = ''
     print('    done - b')