Add OpenGLMobject tests (#2080)

manim/mobject/opengl_mobject.py

@@ -419,8 +419,10 @@ class OpenGLMobject:
             mobjects[0].parent = self
 
         if self in mobjects:
-            raise Exception("Mobject cannot contain self")
+            raise ValueError("OpenGLMobject cannot contain self")
         for mobject in mobjects:
+            if not isinstance(mobject, OpenGLMobject):
+                raise TypeError("All submobjects must be of type OpenGLMobject")
             if mobject not in self.submobjects:
                 self.submobjects.append(mobject)
             if self not in mobject.parents:

tests/conftest.py

@@ -1,8 +1,11 @@
 import os
 import sys
+from pathlib import Path
 
 import pytest
 
+from manim import config, tempconfig
+
 
 def pytest_addoption(parser):
     parser.addoption(
@@ -57,3 +60,13 @@ def reset_cfg_file():
     yield
     with open(cfgfilepath, "w") as cfgfile:
         cfgfile.write(original)
+
+
+@pytest.fixture
+def using_opengl_renderer():
+    """Standard fixture for running with opengl that makes tests use a standard_config.cfg with a temp dir."""
+    with tempconfig({"renderer": "opengl"}):
+        yield
+    # as a special case needed to manually revert back to cairo
+    # due to side effects of setting the renderer
+    config.renderer = "cairo"

tests/opengl/test_opengl_mobject.py

@@ -0,0 +1,50 @@
+import pytest
+
+from manim import config
+from manim.mobject.opengl_mobject import OpenGLMobject
+
+
+def test_opengl_mobject_add(using_opengl_renderer):
+    """Test OpenGLMobject.add()."""
+    """Call this function with a Container instance to test its add() method."""
+    # check that obj.submobjects is updated correctly
+    obj = OpenGLMobject()
+    assert len(obj.submobjects) == 0
+    obj.add(OpenGLMobject())
+    assert len(obj.submobjects) == 1
+    obj.add(*(OpenGLMobject() for _ in range(10)))
+    assert len(obj.submobjects) == 11
+
+    # check that adding a OpenGLMobject twice does not actually add it twice
+    repeated = OpenGLMobject()
+    obj.add(repeated)
+    assert len(obj.submobjects) == 12
+    obj.add(repeated)
+    assert len(obj.submobjects) == 12
+
+    # check that OpenGLMobject.add() returns the OpenGLMobject (for chained calls)
+    assert obj.add(OpenGLMobject()) is obj
+    obj = OpenGLMobject()
+
+    # a OpenGLMobject cannot contain itself
+    with pytest.raises(ValueError):
+        obj.add(obj)
+
+    # can only add OpenGLMobjects
+    with pytest.raises(TypeError):
+        obj.add("foo")
+
+
+def test_opengl_mobject_remove(using_opengl_renderer):
+    """Test OpenGLMobject.remove()."""
+    obj = OpenGLMobject()
+    to_remove = OpenGLMobject()
+    obj.add(to_remove)
+    obj.add(*(OpenGLMobject() for _ in range(10)))
+    assert len(obj.submobjects) == 11
+    obj.remove(to_remove)
+    assert len(obj.submobjects) == 10
+    obj.remove(to_remove)
+    assert len(obj.submobjects) == 10
+
+    assert obj.remove(OpenGLMobject()) is obj

tests/test_scene_rendering/conftest.py

@@ -18,7 +18,9 @@ def simple_scenes_path():
 @pytest.fixture
 def using_temp_config(tmpdir):
     """Standard fixture that makes tests use a standard_config.cfg with a temp dir."""
-    with tempconfig(config.digest_file(Path(__file__).parent / "standard_config.cfg")):
+    with tempconfig(
+        config.digest_file(Path(__file__).parent.parent / "standard_config.cfg"),
+    ):
         config.media_dir = tmpdir
         yield