Don't display() spurious newlines in jupyter

rich/jupyter.py

@@ -83,6 +83,12 @@ def escape(text: str) -> str:
 
 def display(segments: Iterable[Segment], text: str) -> None:
     """Render segments to Jupyter."""
+    segments = list(segments)
+    if not segments and not text:
+        # display() always prints a newline, so if there is no content then
+        # we don't want a single newline appearing.
+        # See https://github.com/Textualize/rich/issues/3274
+        return None
     html = _render_segments(segments)
     jupyter_renderable = JupyterRenderable(html, text)
     try:

tests/test_jupyter.py

@@ -30,3 +30,22 @@ def test_jupyter_lines_env():
     console = Console(
         width=40, _environ={"JUPYTER_LINES": "broken"}, force_jupyter=True
     )
+
+
+def test_jupyter_capture(monkeypatch):
+    # If inside a capture, ipython's display shouldn't be called,
+    # or we would get spurious newlines.
+    # See https://github.com/Textualize/rich/issues/3274
+    called = False
+
+    def mock_display(*args, **kwargs):
+        nonlocal called
+        called = True
+
+    monkeypatch.setattr("IPython.display.display", mock_display)
+    console = Console(force_jupyter=True)
+    with console.capture():
+        console.print("foo")
+    assert not called
+    console.print("foo")
+    assert called