Simplified some test code based on comments

src/ctapipe/image/tests/test_extractor.py

@@ -427,7 +427,7 @@ def test_extractors(Extractor, toymodels, request):
 @pytest.mark.parametrize("Extractor", extractors)
 def test_integration_correction_off(Extractor, toymodels, request):
     # full waveform extractor does not have an integration correction
-    if Extractor is FullWaveformSum or Extractor is VarianceExtractor:
+    if Extractor in (FullWaveformSum, VarianceExtractor):
         return
 
     (
@@ -717,15 +717,12 @@ def test_dtype(Extractor, subarray):
     extractor = Extractor(subarray=subarray)
     n_channels, n_pixels, _ = waveforms.shape
     broken_pixels = np.zeros((n_channels, n_pixels), dtype=bool)
-    if Extractor is VarianceExtractor:
-        var = extractor(waveforms, tel_id, None, None)
-        assert var.image.dtype == np.float32
-        return
-
     dl1 = extractor(waveforms, tel_id, selected_gain_channel, broken_pixels)
 
+    if Extractor is not VarianceExtractor:
+        assert dl1.peak_time.dtype == np.float32
+
     assert dl1.image.dtype == np.float32
-    assert dl1.peak_time.dtype == np.float32
 
 
 def test_global_peak_window_sum_with_pixel_fraction(subarray):