From 72edec6209d8dcebf4f57f09f7de6189896f9ed9 Mon Sep 17 00:00:00 2001
From: Martin Raspaud <martin.raspaud@smhi.se>
Date: Thu, 7 Nov 2019 11:16:48 +0100
Subject: [PATCH] Fix `grid` argument handling in overlaying

---
 satpy/tests/test_writers.py | 24 ++++++++++++++++++++++++
 satpy/writers/__init__.py   | 11 ++++++-----
 2 files changed, 30 insertions(+), 5 deletions(-)

diff --git a/satpy/tests/test_writers.py b/satpy/tests/test_writers.py
index f1459a5644..2b8e6a7391 100644
--- a/satpy/tests/test_writers.py
+++ b/satpy/tests/test_writers.py
@@ -20,6 +20,7 @@
 import errno
 import shutil
 import unittest
+import warnings
 
 import numpy as np
 import xarray as xr
@@ -622,6 +623,29 @@ def test_add_overlay_basic_rgb(self):
                                              pil_args, pil_kwargs, fun_args, fun_kwargs)
                 ContourWriterAGG.assert_called_with(coast_dir)
 
+                # test legacy call
+
+                grid = {'minor_is_tick': True}
+                color = 'red'
+                expected_overlays = {'coasts': {'outline': color, 'width': 0.5, 'level': 1},
+                                     'borders': {'outline': color, 'width': 0.5, 'level': 1},
+                                     'grid': grid}
+                with warnings.catch_warnings(record=True) as wns:
+                    warnings.simplefilter("always")
+                    new_img = add_overlay(self.orig_rgb_img, self.area_def, coast_dir,
+                                          color=color, grid=grid, fill_value=0)
+                    assert len(wns) == 1
+                    assert issubclass(wns[0].category, DeprecationWarning)
+                    assert "deprecated" in str(wns[0].message)
+
+                pil_args = None
+                pil_kwargs = {'fill_value': 0}
+                fun_args = (self.orig_rgb_img.data.area, ContourWriterAGG.return_value, expected_overlays)
+                fun_kwargs = None
+                apply_pil.assert_called_with(_burn_overlay, self.orig_rgb_img.mode,
+                                             pil_args, pil_kwargs, fun_args, fun_kwargs)
+                ContourWriterAGG.assert_called_with(coast_dir)
+
     def test_add_overlay_basic_l(self):
         """Test basic add_overlay usage with L data."""
         from satpy.writers import add_overlay
diff --git a/satpy/writers/__init__.py b/satpy/writers/__init__.py
index 0ac6546ecf..afb319d8e4 100644
--- a/satpy/writers/__init__.py
+++ b/satpy/writers/__init__.py
@@ -265,11 +265,12 @@ def add_overlay(orig_img, area, coast_dir, color=None, width=None, resolution=No
             level_borders = 1
         overlays.setdefault('borders', {}).setdefault('level', level_borders)
 
-        if grid is not None and 'major_lonlat' in grid and grid['major_lonlat']:
-            major_lonlat = grid.pop('major_lonlat')
-            minor_lonlat = grid.pop('minor_lonlat', major_lonlat)
-            grid_params = {'Dlonlat': major_lonlat, 'dlonlat': minor_lonlat}
-            for key, val in grid_params.items():
+        if grid is not None:
+            if 'major_lonlat' in grid and grid['major_lonlat']:
+                major_lonlat = grid.pop('major_lonlat')
+                minor_lonlat = grid.pop('minor_lonlat', major_lonlat)
+                grid.update({'Dlonlat': major_lonlat, 'dlonlat': minor_lonlat})
+            for key, val in grid.items():
                 overlays.setdefault('grid', {}).setdefault(key, val)
 
     cw_ = ContourWriterAGG(coast_dir)