[flake8-bugbear] Fix all the useless expressions that are justified

pyproject.toml

@@ -148,7 +148,6 @@ ignore = [
     "B011", # Do not `assert False` (`python -O` removes these calls)
     "B015", # Pointless comparison. Did you mean to assign a value?
     "B017", # `pytest.raises(Exception)` should be considered evil
-    "B018", # Found useless expression.
     "B023", # Function definition does not bind loop variable `warning`
     "B028", # No explicit `stacklevel` keyword argument found
     # pycodestyle ignore

scripts/update-plugin-list.py

@@ -208,7 +208,7 @@ def main() -> None:
         f.write(f"This list contains {len(plugins)} plugins.\n\n")
         f.write(".. only:: not latex\n\n")
 
-        wcwidth  # reference library that must exist for tabulate to work
+        _ = wcwidth  # reference library that must exist for tabulate to work
         plugin_table = tabulate.tabulate(plugins, headers="keys", tablefmt="rst")
         f.write(indent(plugin_table, "   "))
         f.write("\n\n")

src/_pytest/unittest.py

@@ -209,8 +209,8 @@ class TestCaseFunction(Function):
             )
             # Invoke the attributes to trigger storing the traceback
             # trial causes some issue there.
-            excinfo.value
+            _ = excinfo.value
-            excinfo.traceback
+            _ = excinfo.traceback
         except TypeError:
             try:
                 try:

testing/_py/test_local.py

@@ -1241,9 +1241,9 @@ class TestWINLocalPath:
 
     def test_owner_group_not_implemented(self, path1):
         with pytest.raises(NotImplementedError):
-            path1.stat().owner
+            _ = path1.stat().owner
         with pytest.raises(NotImplementedError):
-            path1.stat().group
+            _ = path1.stat().group
 
     def test_chmod_simple_int(self, path1):
         mode = path1.stat().mode

testing/code/test_excinfo.py

@@ -387,7 +387,7 @@ def test_excinfo_no_python_sourcecode(tmp_path: Path) -> None:
     excinfo = pytest.raises(ValueError, template.render, h=h)
     for item in excinfo.traceback:
         print(item)  # XXX: for some reason jinja.Template.render is printed in full
-        item.source  # shouldn't fail
+        _ = item.source  # shouldn't fail
         if isinstance(item.path, Path) and item.path.name == "test.txt":
             assert str(item.source) == "{{ h()}}:"
 
@@ -418,7 +418,7 @@ def test_codepath_Queue_example() -> None:
 
 def test_match_succeeds():
     with pytest.raises(ZeroDivisionError) as excinfo:
-        0 // 0
+        _ = 0 // 0
     excinfo.match(r".*zero.*")
 
 
@@ -584,7 +584,7 @@ class TestFormattedExcinfo:
         try:
 
             def f():
-                1 / 0
+                _ = 1 / 0
 
             f()
 
@@ -601,7 +601,7 @@ class TestFormattedExcinfo:
             print(line)
         assert lines == [
             "    def f():",
-            ">       1 / 0",
+            ">       _ = 1 / 0",
             "E       ZeroDivisionError: division by zero",
         ]
 
@@ -638,7 +638,7 @@ raise ValueError()
         pr = FormattedExcinfo()
 
         try:
-            1 / 0
+            _ = 1 / 0
         except ZeroDivisionError:
             excinfo = ExceptionInfo.from_current()
 
@@ -1582,7 +1582,7 @@ def test_no_recursion_index_on_recursion_error():
             return getattr(self, "_" + attr)
 
     with pytest.raises(RuntimeError) as excinfo:
-        RecursionDepthError().trigger
+        _ = RecursionDepthError().trigger
     assert "maximum recursion" in str(excinfo.getrepr())
 
 

testing/test_compat.py

@@ -170,9 +170,9 @@ class ErrorsHelper:
 def test_helper_failures() -> None:
     helper = ErrorsHelper()
     with pytest.raises(Exception):
-        helper.raise_exception
+        _ = helper.raise_exception
     with pytest.raises(OutcomeException):
-        helper.raise_fail_outcome
+        _ = helper.raise_fail_outcome
 
 
 def test_safe_getattr() -> None:

testing/test_legacypath.py

@@ -108,7 +108,7 @@ class TestFixtureRequestSessionScoped:
             AttributeError,
             match="path not available in session-scoped context",
         ):
-            session_request.fspath
+            _ = session_request.fspath
 
 
 @pytest.mark.parametrize("config_type", ["ini", "pyproject"])

testing/test_mark.py

@@ -42,7 +42,7 @@ class TestMark:
     def test_pytest_mark_name_starts_with_underscore(self) -> None:
         mark = MarkGenerator(_ispytest=True)
         with pytest.raises(AttributeError):
-            mark._some_name
+            _ = mark._some_name
 
 
 def test_marked_class_run_twice(pytester: Pytester) -> None: