Fix Scene save_datasets to only save datasets from the wishlist

satpy/scene.py

@@ -1011,7 +1011,13 @@ def save_datasets(self, writer="geotiff", datasets=None, compute=True,
         if datasets is not None:
             datasets = [self[ds] for ds in datasets]
         else:
-            datasets = self.datasets.values()
+            datasets = [self.datasets.get(ds) for ds in self.wishlist]
+            datasets = [ds for ds in datasets if ds is not None]
+        if not datasets:
+            raise RuntimeError("None of the requested datasets have been "
+                               "generated or could not be loaded. Requested "
+                               "composite inputs may need to have matching "
+                               "dimensions (eg. through resampling).")
         writer, save_kwargs = load_writer(writer,
                                           ppp_config_dir=self.ppp_config_dir,
                                           **kwargs)

satpy/tests/test_scene.py

@@ -1621,7 +1621,7 @@ def test_save_datasets_default(self):
             os.path.join(self.base_dir, 'test_20180101_000000.tif')))
 
     def test_save_datasets_bad_writer(self):
-        """Save a dataset using 'save_datasets'."""
+        """Save a dataset using 'save_datasets' and a bad writer."""
         from satpy.scene import Scene
         import xarray as xr
         import dask.array as da
@@ -1639,6 +1639,19 @@ def test_save_datasets_bad_writer(self):
                           writer='_bad_writer_',
                           base_dir=self.base_dir)
 
+    def test_save_datasets_missing_wishlist(self):
+        """Calling 'save_datasets' with no valid datasets."""
+        from satpy.scene import Scene, DatasetID
+        scn = Scene()
+        scn.wishlist.add(DatasetID(name='true_color'))
+        self.assertRaises(RuntimeError,
+                          scn.save_datasets,
+                          writer='geotiff',
+                          base_dir=self.base_dir)
+        self.assertRaises(KeyError,
+                          scn.save_datasets,
+                          datasets=['no_exist'])
+
     def test_save_dataset_default(self):
         """Save a dataset using 'save_dataset'."""
         from satpy.scene import Scene