diff --git a/glue_plotly/viewers/common/tests/__init__.py b/glue_plotly/viewers/common/tests/__init__.py
index e69de29..3033646 100644
--- a/glue_plotly/viewers/common/tests/__init__.py
+++ b/glue_plotly/viewers/common/tests/__init__.py
@@ -0,0 +1 @@
+from .base_viewer_tests import BasePlotlyViewTests  # noqa
diff --git a/glue_plotly/viewers/common/tests/base_viewer_tests.py b/glue_plotly/viewers/common/tests/base_viewer_tests.py
new file mode 100644
index 0000000..3fd125c
--- /dev/null
+++ b/glue_plotly/viewers/common/tests/base_viewer_tests.py
@@ -0,0 +1,22 @@
+from uuid import UUID
+
+
+class BasePlotlyViewTests:
+
+    def setup_method(self, method):
+        pass
+
+    def teardown_method(self, method):
+        pass
+
+    def test_unique_class(self):
+        unique_class = self.viewer.unique_class
+        prefix = "glue-plotly-"
+        prefix_len = len(prefix)
+        assert unique_class.startswith(prefix)
+        assert len(unique_class) == prefix_len + 32
+
+        # Test UUID validity by seeing if we can construct a UUID instance
+        assert UUID(unique_class[prefix_len:])
+
+        assert unique_class in self.viewer.figure._dom_classes
diff --git a/glue_plotly/viewers/common/viewer.py b/glue_plotly/viewers/common/viewer.py
index 8d2b12e..6e28012 100644
--- a/glue_plotly/viewers/common/viewer.py
+++ b/glue_plotly/viewers/common/viewer.py
@@ -37,6 +37,9 @@ def __init__(self, session, state=None):
         layout = self._create_layout_config()
         self.figure = go.FigureWidget(layout=layout)
 
+        self._unique_class = f"glue-plotly-{uuid4().hex}"
+        self.figure.add_class(self._unique_class)
+
         self.selection_layer_id = uuid4().hex
         selection_layer = go.Heatmap(x0=0.5,
                                      dx=1,
@@ -156,3 +159,8 @@ def apply_roi(self, roi, use_current=False):
     # TODO: Should we have anything here?
     def redraw(self):
         pass
+
+    @property
+    def unique_class(self):
+        """This is a unique identifier, based on a v4 UUID, that is assigned to the root widget as a class."""
+        return self._unique_class
diff --git a/glue_plotly/viewers/histogram/tests/test_viewer.py b/glue_plotly/viewers/histogram/tests/test_viewer.py
index c192689..0e6c6b9 100644
--- a/glue_plotly/viewers/histogram/tests/test_viewer.py
+++ b/glue_plotly/viewers/histogram/tests/test_viewer.py
@@ -3,10 +3,11 @@
 from plotly.graph_objects import Bar
 
 from glue_plotly.common import DEFAULT_FONT
+from glue_plotly.viewers.common.tests import BasePlotlyViewTests
 from glue_plotly.viewers.histogram import PlotlyHistogramView
 
 
-class TestHistogramViewer:
+class TestHistogramViewer(BasePlotlyViewTests):
 
     def setup_method(self, method):
         self.data = Data(label="histogram", x=[1, 1, 1, 2, 2, 3, 3, 3, 4, 6, 6])
diff --git a/glue_plotly/viewers/scatter/tests/test_viewer.py b/glue_plotly/viewers/scatter/tests/test_viewer.py
index efe0b3d..0554022 100644
--- a/glue_plotly/viewers/scatter/tests/test_viewer.py
+++ b/glue_plotly/viewers/scatter/tests/test_viewer.py
@@ -5,12 +5,14 @@
 from plotly.graph_objects import Scatter
 
 from glue_plotly.common import DEFAULT_FONT
+from glue_plotly.viewers.common.tests import BasePlotlyViewTests
 from glue_plotly.viewers.scatter import PlotlyScatterView
 
 
-class TestScatterView:
+class TestScatterView(BasePlotlyViewTests):
 
     def setup_method(self, method):
+        super().setup_method(method)
         self.data = Data(label="histogram", x=[1, 3, 5, 7, 9], y=[2, 4, 6, 8, 10])
         self.app = JupyterApplication()
         self.app.session.data_collection.append(self.data)
@@ -33,6 +35,7 @@ def setup_method(self, method):
     def teardown_method(self, method):
         self.viewer = None
         self.app = None
+        super().teardown_method(method)
 
     def test_basic(self):
         assert len(self.viewer.layers) == 1