ENH: Move PyperclipException and PyperclipWindowsException to error/_… (pandas-dev#47491)

* ENH: Move PyperclipException and PyperclipWindowsException to error/__init__.py per GH27656

* ENH: add docstring to fixture

* ENH: apply feedback

Author: dataxerik

doc/source/reference/testing.rst

@@ -43,6 +43,8 @@ Exceptions and warnings
    errors.ParserError
    errors.ParserWarning
    errors.PerformanceWarning
+   errors.PyperclipException
+   errors.PyperclipWindowsException
    errors.SettingWithCopyError
    errors.SettingWithCopyWarning
    errors.SpecificationError

pandas/errors/__init__.py

@@ -3,6 +3,8 @@
 """
 from __future__ import annotations
 
+import ctypes
+
 from pandas._config.config import OptionError  # noqa:F401
 
 from pandas._libs.tslibs import (  # noqa:F401
@@ -374,3 +376,22 @@ class IndexingError(Exception):
     >>> s.loc["a", "c", "d"] # doctest: +SKIP
     ... # IndexingError: Too many indexers
     """
+
+
+class PyperclipException(RuntimeError):
+    """
+    Exception is raised when trying to use methods like to_clipboard() and
+    read_clipboard() on an unsupported OS/platform.
+    """
+
+
+class PyperclipWindowsException(PyperclipException):
+    """
+    Exception is raised when pandas is unable to get access to the clipboard handle
+    due to some other window process is accessing it.
+    """
+
+    def __init__(self, message: str) -> None:
+        # attr only exists on Windows, so typing fails on other platforms
+        message += f" ({ctypes.WinError()})"  # type: ignore[attr-defined]
+        super().__init__(message)

pandas/io/clipboard/__init__.py

@@ -58,6 +58,11 @@
 import time
 import warnings
 
+from pandas.errors import (
+    PyperclipException,
+    PyperclipWindowsException,
+)
+
 # `import PyQt4` sys.exit()s if DISPLAY is not in the environment.
 # Thus, we need to detect the presence of $DISPLAY manually
 # and not load PyQt4 if it is absent.
@@ -87,18 +92,6 @@ def _executable_exists(name):
     )
 
 
-# Exceptions
-class PyperclipException(RuntimeError):
-    pass
-
-
-class PyperclipWindowsException(PyperclipException):
-    def __init__(self, message) -> None:
-        # attr only exists on Windows, so typing fails on other platforms
-        message += f" ({ctypes.WinError()})"  # type: ignore[attr-defined]
-        super().__init__(message)
-
-
 def _stringifyText(text) -> str:
     acceptedTypes = (str, int, float, bool)
     if not isinstance(text, acceptedTypes):

pandas/tests/io/test_clipboard.py

@@ -3,6 +3,11 @@
 import numpy as np
 import pytest
 
+from pandas.errors import (
+    PyperclipException,
+    PyperclipWindowsException,
+)
+
 from pandas import (
     DataFrame,
     get_option,
@@ -11,6 +16,8 @@
 import pandas._testing as tm
 
 from pandas.io.clipboard import (
+    CheckedCall,
+    _stringifyText,
     clipboard_get,
     clipboard_set,
 )
@@ -110,6 +117,81 @@ def df(request):
         raise ValueError
 
 
+@pytest.fixture
+def mock_ctypes(monkeypatch):
+    """
+    Mocks WinError to help with testing the clipboard.
+    """
+
+    def _mock_win_error():
+        return "Window Error"
+
+    # Set raising to False because WinError won't exist on non-windows platforms
+    with monkeypatch.context() as m:
+        m.setattr("ctypes.WinError", _mock_win_error, raising=False)
+        yield
+
+
+@pytest.mark.usefixtures("mock_ctypes")
+def test_checked_call_with_bad_call(monkeypatch):
+    """
+    Give CheckCall a function that returns a falsey value and
+    mock get_errno so it returns false so an exception is raised.
+    """
+
+    def _return_false():
+        return False
+
+    monkeypatch.setattr("pandas.io.clipboard.get_errno", lambda: True)
+    msg = f"Error calling {_return_false.__name__} \\(Window Error\\)"
+
+    with pytest.raises(PyperclipWindowsException, match=msg):
+        CheckedCall(_return_false)()
+
+
+@pytest.mark.usefixtures("mock_ctypes")
+def test_checked_call_with_valid_call(monkeypatch):
+    """
+    Give CheckCall a function that returns a truthy value and
+    mock get_errno so it returns true so an exception is not raised.
+    The function should return the results from _return_true.
+    """
+
+    def _return_true():
+        return True
+
+    monkeypatch.setattr("pandas.io.clipboard.get_errno", lambda: False)
+
+    # Give CheckedCall a callable that returns a truthy value s
+    checked_call = CheckedCall(_return_true)
+    assert checked_call() is True
+
+
+@pytest.mark.parametrize(
+    "text",
+    [
+        "String_test",
+        True,
+        1,
+        1.0,
+        1j,
+    ],
+)
+def test_stringify_text(text):
+    valid_types = (str, int, float, bool)
+
+    if isinstance(text, valid_types):
+        result = _stringifyText(text)
+        assert result == str(text)
+    else:
+        msg = (
+            "only str, int, float, and bool values "
+            f"can be copied to the clipboard, not {type(text).__name__}"
+        )
+        with pytest.raises(PyperclipException, match=msg):
+            _stringifyText(text)
+
+
 @pytest.fixture
 def mock_clipboard(monkeypatch, request):
     """Fixture mocking clipboard IO.

pandas/tests/test_errors.py

@@ -28,6 +28,7 @@
         "SettingWithCopyWarning",
         "NumExprClobberingError",
         "IndexingError",
+        "PyperclipException",
     ],
 )
 def test_exception_importable(exc):