Test graph PDF output with more than 1000 points

components/dash-core-components/tests/integration/graph/test_graph_print.py

@@ -0,0 +1,36 @@
+import base64
+
+import pytest
+
+from dash import Dash, dcc
+
+
+@pytest.mark.parametrize("point_count", [1000, 1001])
+def test_grpr001_graph_survives_print(point_count, dash_dcc):
+    app = Dash(__name__)
+    points = list(range(point_count))
+    app.layout = dcc.Graph(
+        id="graph",
+        figure={
+            "data": [{"type": "scatter", "mode": "lines", "x": points, "y": points}],
+            "layout": {"width": 600, "height": 400},
+        },
+    )
+
+    dash_dcc.start_server(app)
+    dash_dcc.wait_for_element("#graph .main-svg")
+
+    driver = dash_dcc.driver
+    if not hasattr(driver, "execute_cdp_cmd"):
+        pytest.skip("print-to-PDF regression requires Chrome DevTools Protocol")
+
+    driver.execute_cdp_cmd("Emulation.setEmulatedMedia", {"media": "print"})
+    pdf = driver.execute_cdp_cmd(
+        "Page.printToPDF", {"printBackground": True, "preferCSSPageSize": True}
+    )
+
+    pdf_bytes = base64.b64decode(pdf["data"])
+    assert pdf_bytes.startswith(b"%PDF")
+    assert len(pdf_bytes) > 1000
+    assert dash_dcc.find_element("#graph .scatterlayer .trace path").is_displayed()
+    assert dash_dcc.get_logs() == []