Fix handling of empty help with addini

Fixes pytest-dev#7394

src/_pytest/config/argparsing.py

@@ -195,14 +195,15 @@ def parse_known_and_unknown_args(
     def addini(
         self,
         name: str,
-        help: str,
+        help: "Optional[str]",
         type: Optional["Literal['pathlist', 'args', 'linelist', 'bool', 'int']"] = None,
         *args,
         **kwargs
     ) -> None:
         """ register an ini-file option.
 
         :param str name: name of the ini-variable
+        :param help: help text to display (``None`` suppresses it).
         :param str type: type of the variable, one of
           ``pathlist``, ``args``, ``linelist``, ``bool``, or ``int``.
         :kwparam default: default value if no ini-file option exists but is queried.

src/_pytest/helpconfig.py

@@ -161,6 +161,8 @@ def showhelp(config: Config) -> None:
     indent = " " * indent_len
     for name in config._parser._ininames:
         help, type, default = config._parser._inidict[name]
+        if help is None:
+            continue
         if type is None:
             type = "string"
         spec = "{} ({}):".format(name, type)
@@ -183,10 +185,10 @@ def showhelp(config: Config) -> None:
             # Display help starting after the spec, following lines indented.
             print(" " * (indent_len - spec_len - 2), end="")
             wrapped = textwrap.wrap(help, wrap_width, break_on_hyphens=False)
-
-            print(wrapped[0])
-            for line in wrapped[1:]:
-                print(indent + line)
+            if wrapped:
+                print(wrapped[0])
+                for line in wrapped[1:]:
+                    print(indent + line)
 
     print()
     print("environment variables:")

testing/test_helpconfig.py

@@ -50,6 +50,36 @@ def test_help(testdir: Testdir) -> None:
     result.stdout.no_fnmatch_line("logging:")
 
 
+def test_help_for_empty_ini_params(testdir: "Testdir") -> None:
+    testdir.makeconftest(
+        """
+        from argparse import SUPPRESS
+
+        def pytest_addoption(parser):
+            parser.addini("t_ini_none", None, default=True, type="bool")
+            parser.addini("t_ini_empty", "", default=True, type="bool")
+
+            parser.addoption("--t_opt_none", help=None)
+            parser.addoption("--t_opt_empty", help="")
+            parser.addoption("--t_opt_suppress", help=SUPPRESS)
+    """
+    )
+    result = testdir.runpytest("--help")
+    result.stdout.fnmatch_lines(
+        [
+            "custom options:",
+            "  --t_opt_none=T_OPT_NONE",
+            "  --t_opt_empty=T_OPT_EMPTY",
+            "",
+            "[pytest] ini-options in the first pytest.ini|tox.ini|setup.cfg file found:",
+            "  t_ini_empty (bool):   ",
+        ]
+    )
+    result_str = result.stdout.str()
+    assert "t_ini_none" not in result_str
+    assert "t_opt_suppress" not in result_str
+
+
 @pytest.mark.parametrize("method", ("runpytest_inprocess", "runpytest_subprocess"))
 def test_help_unconfigures_always(method: str, testdir: Testdir) -> None:
     testdir.makeconftest(