feat: temporarily enable a renderer (#113)

.github/workflows/ci.yml

@@ -26,7 +26,13 @@ jobs:
         pip install -e .[dev]
 
     - name: Linting with Ruff
-      run: ruff .
+      # TODO: fix me! For some reason ruff's isorting
+      # doesn't detect higlass as a local module, so
+      # there are differences with import block sorting locally
+      # and in CI. We should hopefully enable this rule in the future.
+      run: |
+        ruff --ignore I001 .
+        ruff src/ # everything seems to be working in src ...
 
     - name: Formatting with Black
       run: black --check .

src/higlass/__init__.py

@@ -11,6 +11,7 @@
 from higlass_schema import *
 
 import higlass.tilesets
+from higlass._display import renderers
 from higlass.api import *
 from higlass.fuse import fuse
 from higlass.server import HiGlassServer, _create_tileset_helper

src/higlass/_display.py

@@ -1,5 +1,6 @@
 from __future__ import annotations
 
+import contextlib
 import json
 import uuid
 from dataclasses import dataclass, field
@@ -140,6 +141,24 @@ def __call__(self, viewconf: dict, **metadata):
         return {"text/html": html}
 
 
+@contextlib.contextmanager
+def managed_enable(registry: RendererRegistry, reset: str | None):
+    """Temporarily enables a renderer.
+
+    Parameters
+    ----------
+    registry : PluginRegistry
+        The plugin registry to potentially reset the active plugin.
+
+    reset : str | None
+        The previous name of the active plugin.
+    """
+    try:
+        yield registry.get()
+    finally:
+        registry.active = reset
+
+
 @dataclass
 class RendererRegistry:
     """A registery for multiple HiGlass renderers.
@@ -185,7 +204,9 @@ def enable(self, name: str):
         """
         if name not in self.renderers:
             raise ValueError(f"Renderer '{name}' has not been registered.")
+        prev = self.active
         self.active = name
+        return managed_enable(self, prev)
 
     def get(self):
         """Get the enabled renderer."""

test/test_display.py

@@ -1,3 +1,5 @@
+from unittest.mock import MagicMock
+
 import pytest
 
 from higlass._display import HTMLRenderer, RendererRegistry, renderers
@@ -32,6 +34,32 @@ def renderer(viewconf: dict, **metadata):
     assert mimebundle["text/plain"] == "some content"
 
 
+def test_temporary_renderer():
+    registry = RendererRegistry()
+    mock = MagicMock()
+
+    def renderer(viewconf: dict, **metadata):
+        return {
+            "text/plain": "some content",
+        }
+
+    registry.register("foo", renderer)
+    registry.register("mock", mock)
+
+    registry.enable("foo")
+
+    with registry.enable("mock") as render:
+        assert registry.active == "mock"
+        render({"hello": "world"})
+
+    mock.assert_called_once_with({"hello": "world"})
+
+    render = registry.get()
+    mimebundle = render({})
+    assert registry.active == "foo"
+    assert mimebundle["text/plain"] == "some content"
+
+
 def test_html_renderer():
     """Just a smoke test to make sure our html gets a unique ID"""