Fix empty flux menu in Specviz with spectrum in surface brightness un…

…its (spacetelescope#3185)

* Debugging

* Return from flux_unit_selected if no angle unit

* Trying to set spectral y type on first data load

* Working fix that doesn't break tests

* Changelog

* Don't set this if unit conversion doesn't exist

* Add test that fails on main

* Codestyle

* Update jdaviz/configs/specviz/plugins/unit_conversion/unit_conversion.py

CHANGES.rst

@@ -5,7 +5,7 @@ New Features
 ------------
 
 - Added flux/surface brightness translation and surface brightness
-  unit conversion in Cubeviz and Specviz. [#2781, #2940, #3088, #3111, #3113, #3129, #3139, #3149, #3155, #3178]
+  unit conversion in Cubeviz and Specviz. [#2781, #2940, #3088, #3111, #3113, #3129, #3139, #3149, #3155, #3178, #3185]
 
 - Plugin tray is now open by default. [#2892]
 

jdaviz/configs/specviz/plugins/parsers.py

@@ -11,6 +11,7 @@
 from jdaviz.core.events import SnackbarMessage
 from jdaviz.core.registries import data_parser_registry
 from jdaviz.utils import standardize_metadata, download_uri_to_path
+from jdaviz.core.validunits import check_if_unit_is_per_solid_angle
 
 
 __all__ = ["specviz_spectrum1d_parser"]
@@ -159,6 +160,15 @@ def specviz_spectrum1d_parser(app, data, data_label=None, format=None, show_in_v
             # Make metadata layout conform with other viz.
             spec.meta = standardize_metadata(spec.meta)
 
+            # If this is the first loaded data, we want to set spectral y unit type to Flux or
+            # Surface Brightness as appropriate
+            if len(app.data_collection) == 0 and "Unit Conversion" in app._jdaviz_helper.plugins:
+                uc = app._jdaviz_helper.plugins["Unit Conversion"]
+                if check_if_unit_is_per_solid_angle(flux_units):
+                    uc._obj.spectral_y_type = "Surface Brightness"
+                else:
+                    uc._obj.spectral_y_type = "Flux"
+
             app.add_data(spec, data_label[i])
 
             # handle display, with the SpectrumList special case in mind.

jdaviz/configs/specviz/plugins/unit_conversion/tests/test_unit_conversion.py

@@ -35,6 +35,15 @@ def test_value_error_exception(specviz_helper, spectrum1d, new_spectral_axis, ne
     assert u.Unit(viewer.state.y_display_unit) == u.Unit(expected_flux)
 
 
+def test_initialize_specviz_sb(specviz_helper, spectrum1d):
+    spec_sb = Spectrum1D(spectrum1d.flux/u.sr, spectrum1d.spectral_axis)
+    specviz_helper.load_data(spec_sb, data_label="Test 1D Spectrum")
+    plg = specviz_helper.plugins["Unit Conversion"]
+    assert plg._obj.flux_unit == "Jy"
+    assert plg._obj.spectral_y_type == "Surface Brightness"
+    assert plg._obj.angle_unit == "sr"
+
+
 @pytest.mark.parametrize('uncert', (False, True))
 def test_conv_wave_only(specviz_helper, spectrum1d, uncert):
     if uncert is False:

jdaviz/configs/specviz/plugins/unit_conversion/unit_conversion.py

@@ -173,7 +173,7 @@ def _on_glue_x_display_unit_changed(self, x_unit_str):
             self.spectral_unit.selected = x_unit_str
             if not len(self.flux_unit.choices) or not len(self.angle_unit.choices):
                 # in case flux_unit was triggered first (but could not be set because there
-                # as no spectral_unit to determine valid equivalencies)
+                # was no spectral_unit to determine valid equivalencies)
                 self._on_glue_y_display_unit_changed(self.spectrum_viewer.state.y_display_unit)
 
     def _on_glue_y_display_unit_changed(self, y_unit_str):
@@ -204,6 +204,14 @@ def _on_glue_y_display_unit_changed(self, y_unit_str):
         if check_if_unit_is_per_solid_angle(y_unit_str):
             flux_choices = create_flux_equivalencies_list(y_unit * u.sr, x_unit)
             self.flux_unit.choices = flux_choices
+            flux_unit = str(y_unit * u.sr)
+            # We need to set the angle_unit before triggering _on_flux_unit_changed via
+            # setting self.flux_unit.selected below, or the lack of angle unit will make it think
+            # we're in Flux units.
+            self.angle_unit.choices = create_angle_equivalencies_list(y_unit)
+            self.angle_unit.selected = self.angle_unit.choices[0]
+            if flux_unit in self.flux_unit.choices and flux_unit != self.flux_unit.selected:
+                self.flux_unit.selected = flux_unit
 
         # sets the angle unit drop down and the surface brightness read-only text
         if self.app.data_collection[0]: