Display empty or None help parameter for parser option as empty string

changelog/7394.bugfix.rst

@@ -0,0 +1 @@
+Fixed an empty/None help param on parser options from throwing an unexpected error when executing ``pytest --help``.

src/_pytest/helpconfig.py

@@ -170,6 +170,8 @@ def showhelp(config: Config) -> None:
         help, type, default = config._parser._inidict[name]
         if type is None:
             type = "string"
+        if help in (None, ""):
+            raise TypeError("help argument cannot be empty for {}".format(name))
         spec = "{} ({}):".format(name, type)
         tw.write("  %s" % spec)
         spec_len = len(spec)

testing/test_helpconfig.py

@@ -38,6 +38,30 @@ def test_help(testdir):
     )
 
 
+@pytest.mark.parametrize(
+    "conftest",
+    [
+        """
+        def pytest_addoption(parser):
+            parser.addini("test_ini", "", default=True, type="bool")
+    """,
+        """
+        def pytest_addoption(parser):
+            parser.addini("test_ini", None, default=True, type="bool")
+    """,
+    ],
+)
+@pytest.mark.parametrize(
+    "output", ["*TypeError: help argument cannot be empty for test_ini*"]
+)
+def test_empty_or_none_help_param(conftest, output, testdir):
+    """Tests an empty/None help param is displayed correctly.
+    """
+    testdir.makeconftest(conftest)
+    result = testdir.runpytest("--help")
+    result.stderr.fnmatch_lines([output])
+
+
 def test_hookvalidation_unknown(testdir):
     testdir.makeconftest(
         """