tests: verify figure using approval testing

Use ImageReporter to verify result figures by displaying an received and
approved images of the figure in a diff tool

Author: matthiasschaub

tests/approvals/integrationtests/indicators/test_mapping_saturation.py-TestFigure-test_create_figure_manual.approved.png

@@ -3,14 +3,14 @@
 
 import numpy as np
 import plotly.graph_objects as pgo
-import plotly.io as pio
 import pytest
-from approvaltests import Options, verify
+from approvaltests import Options, verify, verify_binary
 
 from ohsome_quality_api.indicators.mapping_saturation.indicator import (
     MappingSaturation,
 )
 from tests.approvaltests_namers import PytestNamer
+from tests.approvaltests_reporters import ImageDiffReporter
 from tests.integrationtests.utils import oqapi_vcr
 
 
@@ -113,15 +113,17 @@ def indicator(self, topic_building_count, feature_germany_heidelberg):
         i.calculate()
         return i
 
-    @pytest.mark.skip(reason="Only for manual testing.")  # comment for manual test
-    def test_create_figure_manual(self, indicator):
-        indicator.create_figure()
-        pio.show(indicator.result.figure)
-
     def test_create_figure(self, indicator):
         indicator.create_figure()
         assert isinstance(indicator.result.figure, dict)
-        pgo.Figure(indicator.result.figure)  # test for valid Plotly figure
+        figure = pgo.Figure(indicator.result.figure).to_image(format="png")
+        verify_binary(
+            figure,
+            ".png",
+            options=Options()
+            .with_reporter(ImageDiffReporter())
+            .with_namer(PytestNamer()),
+        )
 
 
 @oqapi_vcr.use_cassette