Raise TypeError in easy_install.CommandSpec.from_param

newsfragments/4548.feature.rst

@@ -0,0 +1 @@
+Changed the type of error raised by ``setuptools.command.easy_install.CommandSpec.from_param`` on unsupported argument from `AttributeError` to `TypeError` -- by :user:`Avasam`

setuptools/command/easy_install.py

@@ -2068,8 +2068,7 @@ def from_param(cls, param: Self | str | Iterable[str] | None) -> Self:
             return cls(param)
         if param is None:
             return cls.from_environment()
-        # AttributeError to keep backwards compatibility, this should really be a TypeError though
-        raise AttributeError(f"Argument has an unsupported type {type(param)}")
+        raise TypeError(f"Argument has an unsupported type {type(param)}")
 
     @classmethod
     def from_environment(cls):

setuptools/tests/test_easy_install.py

@@ -1332,6 +1332,16 @@ def test_from_simple_string_uses_shlex(self):
         assert len(cmd) == 2
         assert '"' not in cmd.as_header()
 
+    def test_from_param_raises_expected_error(self) -> None:
+        """
+        from_param should raise its own TypeError when the argument's type is unsupported
+        """
+        with pytest.raises(TypeError) as exc_info:
+            ei.CommandSpec.from_param(object())  # type: ignore[arg-type] # We want a type error here
+        assert (
+            str(exc_info.value) == "Argument has an unsupported type <class 'object'>"
+        ), exc_info.value
+
 
 class TestWindowsScriptWriter:
     def test_header(self):