Extract ipy display hook and add tests around it

rich/pretty.py

@@ -1,3 +1,5 @@
+from __future__ import annotations
+
 import builtins
 import inspect
 import os
@@ -52,9 +54,6 @@ if TYPE_CHECKING:
         RenderResult,
     )
 
-# Matches Jupyter's special methods
-_re_jupyter_repr = re.compile(f"^_repr_.+_$")
-
 
 def _is_attr_object(obj: Any) -> bool:
     """Check if an object was created with attrs module."""
@@ -83,6 +82,70 @@ def _is_dataclass_repr(obj: object) -> bool:
         return False
 
 
+def _ipy_display_hook(
+    value: Any,
+    console: Console | None = None,
+    overflow: "OverflowMethod" = "ignore",
+    crop: bool = False,
+    indent_guides: bool = False,
+    max_length: Optional[int] = None,
+    max_string: Optional[int] = None,
+    expand_all: bool = False,
+) -> None:
+    from .console import ConsoleRenderable  # needed here to prevent circular import
+
+    # always skip rich generated jupyter renderables or None values
+    if isinstance(value, JupyterRenderable) or value is None:
+        return
+
+    console = console or get_console()
+    if console.is_jupyter:
+        # Delegate rendering to IPython if the object (and IPython) supports it
+        #  https://ipython.readthedocs.io/en/stable/config/integrating.html#rich-display
+        ipython_repr_methods = [
+            "_repr_html_",
+            "_repr_markdown_",
+            "_repr_json_",
+            "_repr_latex_",
+            "_repr_jpeg_",
+            "_repr_png_",
+            "_repr_svg_",
+            "_repr_mimebundle_",
+        ]
+        for repr_method in ipython_repr_methods:
+            method = getattr(value, repr_method, None)
+            if inspect.ismethod(method):
+                # Calling the method ourselves isn't ideal. The interface for the `_repr_*_` methods
+                #  specifies that if they return None, then they should not be rendered
+                #  by the notebook.
+                try:
+                    repr_result = method()
+                except Exception:
+                    continue  # If the method raises, treat it as if it doesn't exist, try any others
+                if repr_result is not None:
+                    return  # Delegate rendering to IPython
+
+    # certain renderables should start on a new line
+    if isinstance(value, ConsoleRenderable):
+        console.line()
+
+    console.print(
+        value
+        if isinstance(value, RichRenderable)
+        else Pretty(
+            value,
+            overflow=overflow,
+            indent_guides=indent_guides,
+            max_length=max_length,
+            max_string=max_string,
+            expand_all=expand_all,
+            margin=12,
+        ),
+        crop=crop,
+        new_line_start=True,
+    )
+
+
 def install(
     console: Optional["Console"] = None,
     overflow: "OverflowMethod" = "ignore",
@@ -107,8 +170,6 @@ def install(
     """
     from rich import get_console
 
-    from .console import ConsoleRenderable  # needed here to prevent circular import
-
     console = console or get_console()
     assert console is not None
 
@@ -132,59 +193,6 @@ def install(
             )
             builtins._ = value  # type: ignore
 
-    def ipy_display_hook(value: Any) -> None:  # pragma: no cover
-        assert console is not None
-        # always skip rich generated jupyter renderables or None values
-        if isinstance(value, JupyterRenderable) or value is None:
-            return
-        # on jupyter rich display, if using one of the special representations don't use rich
-
-        if console.is_jupyter:
-            # Delegate rendering to IPython if the object (and IPython) supports it
-            #  https://ipython.readthedocs.io/en/stable/config/integrating.html#rich-display
-            ipython_repr_methods = [
-                "_repr_html_",
-                "_repr_markdown_",
-                "_repr_json_",
-                "_repr_latex_",
-                "_repr_jpeg_",
-                "_repr_png_",
-                "_repr_svg_",
-                "_repr_mimebundle_",
-            ]
-            for repr_method in ipython_repr_methods:
-                method = getattr(value, repr_method, None)
-                if inspect.ismethod(method):
-                    # Calling the method ourselves isn't ideal. The interface for the `_repr_*_` methods
-                    #  specifies that if they return None, then they should not be rendered
-                    #  by the notebook.
-                    try:
-                        repr_result = method()
-                    except Exception:
-                        continue  # If the method raises, treat it as if it doesn't exist, try any others
-                    if repr_result is not None:
-                        return  # Delegate rendering to IPython
-
-        # certain renderables should start on a new line
-        if isinstance(value, ConsoleRenderable):
-            console.line()
-
-        console.print(
-            value
-            if isinstance(value, RichRenderable)
-            else Pretty(
-                value,
-                overflow=overflow,
-                indent_guides=indent_guides,
-                max_length=max_length,
-                max_string=max_string,
-                expand_all=expand_all,
-                margin=12,
-            ),
-            crop=crop,
-            new_line_start=True,
-        )
-
     try:  # pragma: no cover
         ip = get_ipython()  # type: ignore
         from IPython.core.formatters import BaseFormatter
@@ -194,7 +202,15 @@ def install(
 
             def __call__(self, value: Any) -> Any:
                 if self.pprint:
-                    return ipy_display_hook(value)
+                    return _ipy_display_hook(
+                        value,
+                        console=get_console(),
+                        overflow=overflow,
+                        indent_guides=indent_guides,
+                        max_length=max_length,
+                        max_string=max_string,
+                        expand_all=expand_all,
+                    )
                 else:
                     return repr(value)
 

tests/test_pretty.py

@@ -1,16 +1,16 @@
-from array import array
-from collections import defaultdict, UserDict, UserList
-from dataclasses import dataclass, field
 import io
 import sys
+from array import array
+from collections import defaultdict, UserDict
 from typing import List
 
 import attr
 import pytest
+from dataclasses import dataclass, field
 
 from rich.console import Console
-from rich.pretty import install, Pretty, pprint, pretty_repr, Node
-
+from rich.pretty import install, Pretty, pprint, pretty_repr, Node, _ipy_display_hook
+from rich.text import Text
 
 skip_py36 = pytest.mark.skipif(
     sys.version_info.minor == 6 and sys.version_info.major == 3,
@@ -44,6 +44,85 @@ def test_install():
     assert sys.displayhook is not dh
 
 
+def test_ipy_display_hook__repr_html():
+    console = Console(file=io.StringIO(), force_jupyter=True)
+
+    class Thing:
+        def _repr_html_(self):
+            return "hello"
+
+    console.begin_capture()
+    _ipy_display_hook(Thing(), console=console)
+
+    # Rendering delegated to notebook because _repr_html_ method exists
+    assert console.end_capture() == ""
+
+
+def test_ipy_display_hook__multiple_special_reprs():
+    """
+    The case where there are multiple IPython special _repr_*_
+    methods on the object, and one of them returns None but another
+    one does not.
+    """
+    console = Console(file=io.StringIO(), force_jupyter=True)
+
+    class Thing:
+        def _repr_latex_(self):
+            return None
+
+        def _repr_html_(self):
+            return "hello"
+
+    console.begin_capture()
+    _ipy_display_hook(Thing(), console=console)
+
+    assert console.end_capture() == ""
+
+
+def test_ipy_display_hook__no_special_repr_methods():
+    console = Console(file=io.StringIO(), force_jupyter=True)
+
+    class Thing:
+        def __repr__(self) -> str:
+            return "hello"
+
+    console.begin_capture()
+    _ipy_display_hook(Thing(), console=console)
+
+    # No IPython special repr methods, so printed by Rich
+    assert console.end_capture() == "hello\n"
+
+
+def test_ipy_display_hook__special_repr_raises_exception():
+    """
+    When an IPython special repr method raises an exception,
+    we treat it as if it doesn't exist and look for the next.
+    """
+    console = Console(file=io.StringIO(), force_jupyter=True)
+
+    class Thing:
+        def _repr_markdown_(self):
+            raise Exception()
+
+        def _repr_latex_(self):
+            return None
+
+        def _repr_html_(self):
+            return "hello"
+
+    console.begin_capture()
+    _ipy_display_hook(Thing(), console=console)
+
+    assert console.end_capture() == ""
+
+
+def test_ipy_display_hook__console_renderables_on_newline():
+    console = Console(file=io.StringIO(), force_jupyter=True)
+    console.begin_capture()
+    _ipy_display_hook(Text("hello"), console=console)
+    assert console.end_capture() == "\nhello\n"
+
+
 def test_pretty():
     test = {
         "foo": [1, 2, 3, (4, 5, {6}, 7, 8, {9}), {}],
@@ -55,7 +134,6 @@ def test_pretty():
 
     result = pretty_repr(test, max_width=80)
     print(result)
-    # print(repr(result))
     expected = "{\n    'foo': [1, 2, 3, (4, 5, {6}, 7, 8, {9}), {}],\n    'bar': {\n        'egg': 'baz',\n        'words': [\n            'Hello World',\n            'Hello World',\n            'Hello World',\n            'Hello World',\n            'Hello World',\n            'Hello World',\n            'Hello World',\n            'Hello World',\n            'Hello World',\n            'Hello World'\n        ]\n    },\n    False: 'foo',\n    True: '',\n    'text': ('Hello World', 'foo bar baz egg')\n}"
     print(expected)
     assert result == expected