plots: support opening plots file directly in the browser (#5584)

* plots: support opening plots file directly in the browser

* add tests

* fix path on windows tests

dvc/command/plots.py

@@ -45,13 +45,20 @@ class CmdPlots(CmdBase):
             path = os.path.join(os.getcwd(), path)
 
             write(path, plots)
-
-            logger.info(f"file://{path}")
-
+            url = f"file://{path}"
         except DvcException:
             logger.exception("")
             return 1
 
+        logger.info(url)
+        if self.args.open:
+            import webbrowser
+
+            opened = webbrowser.open(url)
+            if not opened:
+                logger.error("Failed to open. Please try opening it manually.")
+                return 1
+
         return 0
 
 
@@ -229,3 +236,9 @@ def _add_output_arguments(parser):
         default=False,
         help="Show output in Vega format.",
     )
+    parser.add_argument(
+        "--open",
+        action="store_true",
+        default=False,
+        help="Open plot file directly in the browser.",
+    )

tests/unit/command/test_plots.py

@@ -1,3 +1,5 @@
+import logging
+
 from dvc.cli import parse_args
 from dvc.command.plots import CmdPlotsDiff, CmdPlotsShow
 
@@ -55,7 +57,7 @@ def test_plots_diff(dvc, mocker):
     )
 
 
-def test_plots_show(dvc, mocker):
+def test_plots_show_vega(dvc, mocker):
     cli_args = parse_args(
         [
             "plots",
@@ -85,7 +87,7 @@ def test_plots_show(dvc, mocker):
     )
 
 
-def test_plots_show_vega(dvc, mocker, caplog):
+def test_plots_diff_vega(dvc, mocker, caplog):
     cli_args = parse_args(
         [
             "plots",
@@ -103,3 +105,39 @@ def test_plots_show_vega(dvc, mocker, caplog):
     )
     assert cmd.run() == 0
     assert "plothtml" in caplog.text
+
+
+def test_plots_diff_open(tmp_dir, dvc, mocker, caplog):
+    mocked_open = mocker.patch("webbrowser.open", return_value=True)
+    cli_args = parse_args(["plots", "diff", "--targets", "datafile", "--open"])
+    cmd = cli_args.func(cli_args)
+    mocker.patch(
+        "dvc.repo.plots.diff.diff", return_value={"datafile": "filledtemplate"}
+    )
+
+    assert cmd.run() == 0
+
+    expected_url = f"file://{tmp_dir / 'plots.html'}"
+    assert expected_url in caplog.text
+
+    mocked_open.assert_called_once_with(expected_url)
+
+
+def test_plots_diff_open_failed(tmp_dir, dvc, mocker, caplog):
+    mocked_open = mocker.patch("webbrowser.open", return_value=False)
+    cli_args = parse_args(["plots", "diff", "--targets", "datafile", "--open"])
+    cmd = cli_args.func(cli_args)
+    mocker.patch(
+        "dvc.repo.plots.diff.diff", return_value={"datafile": "filledtemplate"}
+    )
+
+    assert cmd.run() == 1
+
+    expected_url = f"file://{tmp_dir / 'plots.html'}"
+    mocked_open.assert_called_once_with(expected_url)
+
+    error_message = "Failed to open. Please try opening it manually."
+    assert caplog.record_tuples == [
+        ("dvc.command.plots", logging.INFO, expected_url),
+        ("dvc.command.plots", logging.ERROR, error_message),
+    ]